Terry's Astronomy Thread.

[Reach]

Re: Terry's Astronomy Thread.

Fantastic thread, even for casuals just looking at the pictures.

I absolutely love the picture from April 12. I don't see this video posted anywhere in this thread, so:

http://www.youtube.com/watch?v=FG0fTKAqZ5g

An incredible time-lapse from the ISS for those interested.

[gold stinger]

Re: Terry's Astronomy Thread.

This thread is the most up-to-date thread I've ever seen. D:

[Winrar]

Re: Terry's Astronomy Thread.

Even though I don't understand a lot of it. The pictures are amazing and open my eyes to what we're all missing out on. There's just so much we don't know.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Thanks Reach, gold stinger, Winrar for the positive feedback! Reach, I have added the ISS video under the ISS tab because that's a great video and really gives perspective on what it's like to see the Earth from above.

If there's something you want to see added to the thread, post a suggestion! It might just start appearing in the main post.

What's in the sky tonight?
April 16, 2012

-As twilight fades, Look for bright Sirius in the southwest, Orion's horizontal Belt off to the right (with Betelgeuse above it, Rigel below it), and Aldebaran and Venus farther to the right in the west. As it sinks ever lower in the west, notice how it starts twinkling more violently, even temporarily changing colours to yellows and reds. Why is this? As it lowers into the horizon, Sirius and other stars have more atmosphere to travel to from your eyes to the location of the star. Because of this, the light of the star is often distorted through the increased atmosphere and can be strong enough to change what colour rays reach your eyes. This is the same reason why the Sun rises reddish in colour, and why the moon also rises in a red-orange colour. It also explains their often distorted and enlarged shape. Take this picture of the sun for example.

-Mercury (magnitude +0.4) is deep in the glow of sunrise. It's having a very poor dawn apparition just above the eastern horizon.

-Neptune (magnitude 7.9, in Aquarius) is barely emerging into view low in the east-southeast before dawn's first light. Both of these planets were hidden in the glare of the sun last week.

Astro Picture of the Day:
April 16, 2012

Source:
From afar, the whole thing looks like an Eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. Through this window, a brightly-lit workshop appears where a whole open cluster of stars is being formed. In this cavity tall pillars and round globules of dark dust and cold molecular gas remain where stars are still forming. Already visible are several young bright blue stars whose light and winds are burning away and pushing back the remaining filaments and walls of gas and dust. The Eagle emission nebula, tagged M16, lies about 6500 light years away, spans about 20 light-years, and is visible with binoculars toward the constellation of the Serpent (Serpens). This picture combines three specific emitted colors and was taken with the 0.9 meter telescope on Kitt Peak, Arizona, USA. The famous pillars are seen at the centre of this nebula.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 17, 2012

-The eclipsing variable star Algol is at minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:44 p.m. EDT (9:44 p.m. CDT). This is the last chance till August to see Algol at minimum from the latitudes of the U.S.
-Mercury (magnitude +0.4) is deep in the glow of sunrise. It's having a very poor dawn apparition just above the eastern horizon.

-Keep careful watch on Saturn and its rings in a telescope. With Saturn at or near near opposition, notice the Seeliger effect: a temporary brightening of the rings with respect to the globe. This happens because the solid particles making up the rings backscatter sunlight (reflect it back in the direction it came from) more effectively than the planet's cloudtops do. Compare how the rings and globe look now with with how they look a week or more past opposition. By April 12th, three days before Saturn's opposition, the planet's rings had already brightened quite noticeably due to the Seeliger effect. South is up. A comparison image by the same photographer has been posted below.

Astro Picture of the Day:
April 17, 2012

Source:
Antares is a huge star. In a class called red supergiant, Antares is about 850 times the diameter of our own Sun, 15 times more massive, and 10,000 times brighter. Antares is the brightest star in the constellation of Scorpius and one of the brighter stars in all the night sky. Located about 550 light years away, Antares is seen on the left surrounded by a yellowish nebula of gas which it has itself expelled. Radiation from Antares' blue stellar companion helps cause the nebular gas to glow. Far behind Antares, to the lower right in the above image, is the globular star cloud M4, while the bright star on the far right is Al Niyat.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 18, 2012

-This is the time of year when the dim Little Dipper juts to the right from Polaris (its handle-end) at nightfall. The much brighter Big Dipper curls over high above it, "dumping water" straight down into it.

-Jupiter (magnitude –2.0) is sinking ever lower toward the sunset, far below Venus. It's rounding toward the far side of the Sun, which is why a telescope shows it a disappointingly small 33 arcseconds wide. In addition, Jupiter appears increasingly fuzzy at its ever-lower altitude.

Astro Picture of the Day:
April 18, 2012

Source:
What would it be like to fly a space shuttle? Although the last of NASA's space shuttles has now been retired, it is still fun to contemplate sitting at the controls of one of the humanity's most sophisticated machines. Pictured above is the flight deck of Space Shuttle Endeavour, the youngest shuttle and the second to last ever launched. The numerous panels and displays allowed the computer-controlled orbiter to enter the top of Earth's atmosphere at greater than the speed of sound and -- just thirty minutes later -- land on a runway like an airplane. The retired space shuttles are now being sent to museums, with Endeavour being sent to California Space Center in Los Angeles, California, Atlantis to the Kennedy Space Center Visitor Complex on Merritt Island, Florida, and Discovery to the Udvar-Hazy Annex of the National Air and Space Museum in Chantilly, Virginia. Therefore sitting in a shuttle pilot's chair and personally contemplating the thrill of human space flight may actually be in your future.

What's in the Sky Tonight Archive August 1, 2013 - December 31, 2013

December 31, 2013

-After the New Year's cheering at midnight, step outside into the silent dark. Sirius shines almost due south. Jupiter, even brighter, beams much higher to the south. Orion strides to the upper right of Sirius. Procyon shines to Sirius's upper left, and Leo is climbing the eastern sky.

December 30, 2013

-When evening twilight turns to night at year's end, the constellation Andromeda is crossing the zenith (for the world's mid-northern latitudes). The Great Andromeda Galaxy passes right through your zenith if you're near latitude 41° north (New York, Denver, Madrid). This happens at 6:05 p.m. tonight if you live at your time zone's standard longitude. If you're east or west of there, as you probably are, the galaxy will transit as much as 30-plus minutes earlier or later, respectively. Lie on your back and look straight up with binoculars for a dim, elongated little glow of fuzzy gray among the pinpoint stars.

-Energetic protons are swarming past Earth in the aftermath of a magnetic explosion on the sun's western limb on Dec. 28th: movie. At its peak, the radiation storm registered "S1" on NOAA storm scales, which is to say it was a minor event with minimal effects on Earth-orbiting satellites and aviation. The storm is subsiding now. Stronger radiation storms are possible in the days ahead, however, as potent sunspot AR1934 rotates toward the western limb--a place with a strong magnetic connection to Earth. Flares from AR1934 could send more protons in our direction.

-Magnetic fields in the sun's northern hemisphere have opened up, creating a vast hole in the sun's atmosphere - a coronal hole. NASA's Solar Dynamics Observatory is monitoring the UV-dark gap. Coronal holes are places where magnetic fields threading through the sun's atmosphere spread apart and allow solar wind to escape. A stream of solar wind flowing from this particular coronal hole could reach Earth on Jan. 2-3, possibly sparking polar geomagnetic storms. The first auroras of 2014 are in the offing.

December 29, 2013

-Energetic protons are swarming around Earth on Dec. 29th following a magnetic eruption near the western limb of the sun. The ongoing radiation storm ranks S1 on NOAA storm scales, which means it is a relatively minor storm with little effect on spacecraft and high-altitude aviation.

-Now is a great time to look at the second planet from the sun. Like the Moon, Venus has phases, and at the moment it is a 6% crescent. Moreover, it is bright enough to see in broad daylight. Yesterday, Mark Wloch pointed his Celestron C8 telescope at the blue sky over Southgate, Michigan, and this is what he saw.

"I captured Venus during daylight with a jet passing by," says Wloch. "What a beautiful conjunction."

Yes, it is easy to see Venus in broad daylight, but it is even easier to see the planet at sunset when Venus pierces the darkening sky like a beacon 150 times brighter than a 1st-magnitude star. Indeed, some sky watchers think Venus is an airplane. A quick look through a pair of binoculars, however, reveals the crescent. Point your optics southwest after sunset. No sky map is required; you can't miss Venus.

-AR1936 is waking up. The sunspot has a 'beta-gamma-delta' magnetic field that harbors energy for strong eruptions, yet it has been quiet for days. Now AR1936 is beginning to crackle with flares. NASA's Solar Dynamics Observatory recorded the extreme ultraviolet flash from an almost-M-class flare at 1800 UT on Dec. 28th. Because the sunspot is facing Earth, any flares emanating from it are going to be geoeffective. So far, the extreme ultraviolet "crackles" have produced only minor waves of ionization in our planet's upper atmosphere. Earth-effects will increase, however, if the activity continues to intensify. Stay tuned!

December 28, 2013

-Very late tonight, tomorrow, and Monday nights, Mars is just 3/4° from Gamma Virginis (Porrima), magnitude 2.7 — a famous close double star for telescopes at high power. Mars and Gamma Vir rise together after midnight and are best seen high in the south before dawn.

-Dawn is now coming its latest of the year. Step out early enough and you can watch the waning Moon passing Saturn and Antares.

-This week, there was a storm on Jupiter - a radio storm. Amateur radio astronomer Thomas Ashcraft recorded the event on Dec. 23rd using a shortwave radio telescope located in New Mexico. Here is what he captured: http://www.spaceweather.com/images20..._Ashcraft1.mp3

-"Although few were aware of it, Earth was bathed in Jovian radio beams for an hour and half," says Ashcraft. "The audio recording captures the sounds I heard during one minute around 09:30 UT."
Jupiter's radio storms are caused by natural radio lasers in the planet's magnetosphere that sweep past Earth as Jupiter rotates. Electrical currents flowing between Jupiter's upper atmosphere and the volcanic moon Io can boost these emissions to power levels easily detected by ham radio antennas on Earth. Jovian "S-bursts" (short bursts) and "L-bursts" (long bursts) mimic the sounds of woodpeckers, whales, and waves crashing on the beach.

S-Burst: http://radiojove.gsfc.nasa.gov/obser...s/sbursts1.wav
S-Bursts slowed down 128:1: http://radiojove.gsfc.nasa.gov/obser...ts1_slowed.wav
L-Burst: http://radiojove.gsfc.nasa.gov/obser...s/lbursts1.wav

-Now is a good time to listen to Jupiter's radio storms. The distance between Earth and Jupiter is decreasing as the giant planet approaches opposition on Jan. 5th; and the closer Jupiter comes, the louder it gets. Jupiter is a bit like a lighthouse. It is possible to predict when the planet's most intense radio beams will sweep past Earth. The next storm is due on Dec. 30th between 10:00 and 11:00 UT.

December 27, 2013

-Venus (about –4.5) is dropping lower in evening twilight every day. Look southwest. Optical aid shows it becoming an ever thinner crescent: from 7% sunlit on December 27th to just 2% lit on January 4th. But it's big! —about 59 arcminutes in diameter. Good binoculars will show its crescent shape in twilight.

-The best time to observe Venus in a telescope is well before sunset. Hide the Sun behind a building so you can't accidentally sweep it into your view. See this article on more information about Venus's inferior onjunction. http://www.skyandtelescope.com/obser...236245001.html Venus is heading to inferior conjunction with the Sun on January 11th.

-Two sunspots facing Earth (AR1934 and AR1936) have 'beta-gamma' magnetic fields that harbor energy for strong flares. Both sunspots have been quiet for days, however, and they show no signs of an imminent eruption. This has prompted NOAA forecasters to place low odds on flares today: a 25% chance of M-flares and a 1% chance X-flares.

December 26, 2013

-Sirius sparkles low in the east-southeast after dinnertime. Procyon shines in the east about two fist-widths at arm's length to Sirius's left. If you live around north latitude 30° (Tijuana, New Orleans, Jacksonville), these Big and Little Dog Stars are at the same height above your horizon soon after they rise. If you're north of that latitude, Procyon will be higher. If you're south of there, Sirius leads.

-Sunspot AR1934 has a 'beta-gamma' magnetic field that harbors energy for M-class solar flares. Because the region is directly facing Earth, any flares today would surely be geoeffective. The sunspot has been relatively quiet for days, however, so NOAA forecasters are estimating only a 25% chance of M-flares.

-Christmas is over, but the amazing "Christmas conjunction" is still underway. As seen from NASA's STEREO-B spacecraft, the three planets Venus, Earth and Jupiter are clustered in a circle barely 2 degrees wide. The spacecraft's Heliospheric Imager took this picture on Dec. 26th.

-Because of the holidays, this conjunction in space raises comparisons to a famous Christmas conjunction on Earth. According to some scholars, the Star of Bethlehem might have been a close encounter between Venus and Jupiter. The two brightest planets in the night sky, merged, would have made a spectacle so amazing that we still talk about it ~2000 years later.

Unlike conjunctions of the distant past, this one includes our home planet. STEREO-B is located on the far side of the sun where it can look back and see Earth along with other worlds in the Solar System. From STEREO-B's point of view, Jupiter and Venus about 0.5 degrees apart. That is not nearly as tight as the putative Star of Bethlehem conjunction when those two planets were separated by as little as 6 arcseconds (0.00166 degrees). Nevertheless, the Christmas conjunction of 2013 is special because it includes Earth - the first time in history such a conjunction is possible. Happy holidays from STEREO!

December 25, 2013

-At this time every year Sirius rises in the east-southeast down below Orion around 7 or 8 p.m. (depending on your location). When Sirius is still low, binoculars often show it twinkling in vivid colors. All stars do this when low, but Sirius is the brightest, making the effect more pronounced.

-Merry Sol Invictus! In late Roman times when the solstice fell on December 25th, this date was celebrated as Dies Natalis Solis Invicti, the Birthday of the Unconquered Sun — when the Sun began to reverse its long decline with the hopeful promise, in the cold and the dark, of a new spring and summer to come.

-From STEREO-B's point of view, Earth and Jupiter are less than 0.4 degrees apart, while all three planets fit in a circle 2 degrees in diameter. This meeting is not nearly as tight as the putative Star of Bethlehem conjunction ~2000 years ago. At that time Venus and Jupiter could have been as little as 6 arcseconds (0.00166 degrees) apart. Nevertheless, the ongoing display is still special because it's the first "Christmas Star conjunction" from space.

-The star RS Puppis sparkles in the Southern Hemisphere, brightening by a factor of five roughly every six weeks. It’s a supergiant star, 200 times the size of the Sun and 15,000 times as luminous. And more importantly, it’s a Cepheid variable, a “standard candle” whose pulsations are inextricably linked to its luminosity and therefore to its distance. So astronomers were delighted to discover some time ago that the star is enshrouded in a veil of reflective dust, which is unusual for Cepheids. The gossamer nebula may be a remnant of the cloud in which the star formed. The nebula and the way the cepheid star interacts with it is shown in the video below.

December 24, 2013

-The last-quarter Moon shines near Mars after they rise late tonight and into the Christmas-morning dawn.

-Big sunspot AR1928 is crackling with M-class solar flares. Magnetic fields spiraling away from the sunspot's location on the sun's western limb are well-connected to Earth, raising the possibility of a radiation storm around our planet if the flares intensify. NOAA forecasters estimate a 60% chance of M-class flares and a 10% chance of X-class flares on Dec. 23rd.

-According to some scholars, the Star of Bethlehem might have been a close encounter between Venus and Jupiter. The two brightest planets in the night sky, merged, would have made a spectacle of Biblical proportions. This Christmas, NASA's STEREO-B probe is observing something similar. Instead of Jupiter and Venus merging, however, the combined planets are Jupiter and Earth.

STEREO-B is located on the far side of the sun where it can look back and see Earth along with other planets in the Solar System. From STEREO-B's point of view, Earth and Jupiter are so close together that the spacecraft's Heliospheric Imager can barely tell the two apart. Venus is only 2 degrees from the Earth-Jupiter pair, so this is actually a 3-way conjunction.

This meeting is not nearly as tight as the putative Star of Bethlehem conjunction ~2000 years ago. At that time Venus and Jupiter could have been as little as 6 arcseconds (0.00166 degrees) apart. Nevertheless, the ongoing display is still special because it's the first "Christmas Star conjunction" from space. Happy Holidays from STEREO!

December 23, 2013

-With fall gone and winter here, the Great Square of Pegasus is again tipped up onto one corner after dinnertime, now descending on the western side of the sky. The main line of Andromeda's stars extends up from its top corner.

-Big sunspot AR1928 is crackling with M-class solar flares. Magnetic fields spiraling away from the sunspot's location on the sun's western limb are well-connected to Earth, raising the possibility of a radiation storm around our planet if the flares intensify. NOAA forecasters estimate a 60% chance of M-class flares and a 10% chance of X-class flares on Dec. 23rd.

-According to some scholars, the Star of Bethlehem might have been a close encounter between Venus and Jupiter. The two brightest planets in the night sky, merged, would have made a spectacle of Biblical proportions. This Christmas, NASA's STEREO-B probe is observing a conjunction of three planets-Venus, Earth and Jupiter.

Unlike conjunctions of the distant past, this one includes our home planet. STEREO-B is located on the far side of the sun where it can look back and see Earth along with other worlds in the Solar System. Only NASA's twin STEREO probes, equipped with their high dynamic-range Heliospheric Imagers, can witness this kind of conjunction.

From STEREO-B's point of view, Earth and Jupiter are less than 0.5 degrees apart, while all three planets fit in a circle 3 degrees in diameter. This meeting is not nearly as tight as the putative Star of Bethlehem conjunction ~2000 years ago. At that time Venus and Jupiter could have been as little as 6 arcseconds (0.00166 degrees) apart. Nevertheless, the ongoing conjunction is still a beauty. Stay tuned for updates as the three planets converge.

December 22, 2013

-Earth is passing through a stream of debris from Comet 8P/Tuttle, source of the annual Ursid meteor shower. Forecasters expect the shower to peak on Dec. 22nd with as many as 10 meteors per hour streaming from a radiant near Polaris, the North Star. Occasionally, Earth hits a denser-than-usual patch of debris and rates increase 5- to 10-fold. However, no one can predict when these outbursts occur.

-If you took a picture of the sun at the same time each day, would it remain in the same position? The answer is no, and the figure-8 shape traced out by the sun over the course of a year is called an analemma.

Japanese photographer "Shiraishi" stitched together more than 50 pictures spanning 12 months to reveal the analemma of 2013 over the city of Kumagaya-shi in Saitama, Japan.

"My analemma project started on December solstice in 2012 and finished on December solstice in 2013," says Shiraishi. "This photo contains the sun images from Jan. 18 to Dec. 22, that is, all the sun images are only in 2013."

The upper and lower tips of the "8" represent the solstices-the longest and shortest days of the year. Today the Japanese sun is at the bottom. Winter has arrived!

Other planets have analemmas, too. Not all are figure-8s, however. The shape depends on the tilt of the planet's spin axis and the eccentricity of its orbit around the sun. Martian analemmas resemble a teardrop, while Jupiter's analemma looks like a jelly-bean.

December 21, 2013

-Today is the shortest day of the year in the Northern Hemisphere; the longest day in the Southern Hemisphere. Winter in the north, and summer in the south, begins at the solstice: 12:11 p.m. Eastern Standard Time. This is when the Sun reaches its farthest point south for the year and begins its six-month northward return. Happy Yule.

-If there's one constellation that everyone should know at this time of year, it's wintry Orion climbing up in the east-southeast. As always when Orion is on the rise, the three-star Belt of Orion in its middle is nearly vertical. Show someone Orion this week and they'll know it for a lifetime.

-On Dec. 19th, the European Space Agency launched one of the most ambitious astronomy missions ever: GAIA, an observatory that will survey more than one billion stars in the Milky Way. By the time GAIA's five year mission is over, astronomers will be able to build the first accurate three-dimensional map of celestial objects in our home galaxy. GAIA will do its work from the L2 Lagrange point approximately 1.5 million km from Earth. On Dec. 20th, amateur astronomer Dave Eagle of Higham Ferrers UK observed the spacecraft hurtling toward that distant station.

"It was great to see the spacecraft in the exact position predicted, near the shield of Orion," says Eagle. "After watching the launch live on the Web in the morning, I was glad to be able to track it down and wish it well in its coming mission. It was much brighter than I expected, so its newly deployed Sun shield is doing a great job."

Once it reaches its L2 parking orbit and begins observing, GAIA will log the position, brightness and color of every star that falls within its field of view. By repeating these observations throughout its mission, astronomers will be able to calculate the distance, speed and direction of motion of each star GAIA sees, chart variations in their brightness, and determine whether they have nearby companions. This kind of detailed information about the Milky Way is unprecedented and may lead to important new discoveries about the evolution and structure of our galaxy. For updates about GAIA, stay tuned to the ESA. http://www.spaceweather.com/images20...a.20131219.avi

December 20, 2013

-This evening, use a telescope to watch Io disappear into eclipse by the shadow of Jupiter around 9:15 p.m. Eastern Standard Time, barely off Jupiter's western limb. Forty-five minutes later, Ganymede emerges onto dark sky in front of Jupiter's western limb. Then around 11:23 p.m. EST, the Great Red Spot (strong orange this season) transits Jupiter's central meridian.

-The northern winter solstice is only one day away. In the Netherlands that means it's time to open up a beer can and look inside. Every six months, Jan Koeman of Zierikzee, the Netherlands, deploys a beer-can solargraph to record the progress of seasons, solstice to solstice. On Dec. 18th he cracked his open and below is what he saw. "I made a solargraph using an empty beer tin with a pinhole and photographic paper inside," explains Koeman. "The exposure time is 6 months!"

The highest arcs were traced by the summer sun ofJune 2013. The lowest arc was made by the sun on Dec. 18th, just three days before the 2013 winter solstice. Occasional gaps are caused by clouds.

"This year I placed my solargraph high and safe on an old Dutch windmill," continues Koeman. "The miller is always busy and we have a lot of wind here, so the spinning wings of the mill are barely visible in the photo."

Northern winter begins on Dec. 21st at 17:11 UT. Now is the perfect time to deploy your own beer-can solargraph for the next six months.Soda cans work, too. Want to know how you can build one? Consult these walkthroughs:

http://inatarius.wordpress.com/2009/07/01/solargraph-building-guide/

http://www.pinholephotography.org/Solargraph%20instructions%202.htm

http://www.pinholephotography.org/How%20to%20do%20it.htm

December 19, 2013

-Once the waning gibbous Moon rises after dinnertime, you'll find Jupiter above it, Pollux and Castor left of Jupiter, and Procyon to the Moon's right or lower right. Much farther right of Procyon, watch for brilliant Sirius coming up.

-Jupiter (magnitude –2.7, in Gemini) rises in the east-northeast around the end of twilight, with Pollux and Castor to its left. It blazes highest around 1 or 2 a.m. In a telescope Jupiter has grown to a big 46 arcseconds wide as it nears its January 5th opposition.

December 18, 2013

-The Moon and Jupiter shine together after they rise in early evening, with Pollux and Castor to their left. Although Jupiter looks close to the Moon, it's 1,600 times farther away.

-Next week, Comet Lovejoy makes its closest approach to the sun. The comet's tail is already amazing. The image below taken by Gerald Rhemann of Jauerling, Austria, details its length. Filled with knots and eddies of dusty plasma, Lovejoy's tails stretches more than 20 degrees across the sky-long enough to overlap 40 full Moons or fill the Bowl of the Big Dipper twice. At closest approach to the sun or "perihelion" on Dec. 23rd, the comet will be just inside the orbit of Earth (0.82 AU). The extra heating it gets at perihelion will grow the tail even more.

Comet Lovejoy shines like a 4th magnitude star so it is barely visible to the unaided eye (especialy when the sky is filled with full moonlight). However, for backyard telescopes, the comet is a fairly easy target rising ahead of the sun in the eastern morning sky.

December 17, 2013

-The bright Moon shines in the dim Club of Orion this evening (for the Americas). No, the Moon doesn't always stay quite within the constellations of the zodiac. Lower left of the Moon is Jupiter, and lower right of it is Betelgeuse.

-The face of the sun is peppered with spots, but none of them is actively flaring. Solar activity is low on Dec. 17th.

-Most craters on the Moon were formed millions or even billions of years ago. NASA's Lunar Reconnaisance Orbiter just found one, however, that is only 9 months old. On March 17, 2013, a bright flash of light emerged from Mare Imbrium, the Sea of Rains. Researchers concluded that a small asteroid about 0.4 meters wide hit the lunar surface and exploded like 5 tons of TNT. Here is the crater it made.

-Lunar Reconnaisance Orbiter's LROC camera photographed the crater in July when the spacecraft made a routine pass over the impact site. Subsequent analyses presented at last week's American Geophysical Union meeting linked the crater to the March 17th impact. According to the LROC photo, the crater is 18 meters (59 feet) wide. Together with the bright rays of fresh ejecta ringing the central gouge, the entire impact mark spans an area of lunar terrain half the size of an American football field.

-Unlike Earth, which has an atmosphere to protect it, the airless Moon is baldly exposed to incoming asteroids. NASA's Meteoroid Environment Office monitors the lunar surface for signs of ongoing impacts. Since 2005 they have detected flashes of light from more than 300 explosions. The March 17th event was the brightest they'd ever seen, 10 times more luminous than any other lunar meteor in the history of the program. LROC's detection of a crater in Mare Imbrium provides the kind of "ground truth" measurement they need to calibrate the entire dataset.

December 16, 2013

-Full Moon tonight (exact at 4:28 a.m. Tuesday morning EST). As the Moon climbs the eastern sky this evening, look for Aldebaran to its upper right, Aldebaran-colored Betelgeuse to its lower right, Capella farther to its upper left, and Jupiter far to its lower left.

-A pair of Earth-facing sunspots, AR1917 and AR1918, have 'beta-gamma' magnetic fields that harbor energy for moderately strong solar flares. Any eruptions from the duo in the days ahead would likely be geoeffective. NOAA forecasters estimate a 25% chance of M-class flares during the next 24 hours.

-On Dec. 15, 2013, the network reported 52 fireballs. ( 30 Geminids, 20 sporadics, 2 December Leonis Minorids)

December 15, 2013

-NOAA forecasters estimate a 40% chance of polar geomagnetic storms on Dec. 15th when a pair of CMEs could deliver rapid-fire glancing blows to Earth's magnetic field. High-latitude sky watchers should be alert for auroras mixed with bright moonlight.

-China has joined the club of nations that has landed on the Moon. On Saturday, Dec. 14th, at 9:41 p.m. Beijing local time, China's Chang’e-3 lunar lander touched down in Sinus Iridum, the Bay of Rainbows. Hours later, a lunar rover named the Jade Rabbit ("Yutu" in Mandarin Chinese) emerged for a historic mission of exploration.

The six-wheeled, 260-lb rover is equipped with a Chinese-made nuclear battery expected to last for more than 30 years. The rover also has expandable solar arrays to absorb the sun’s energy during the day and retract at night to cover and protect equipment from temperatures of minus 170 degrees Celsius. Onboard sensors include a ground-probing radar, cameras, and a soil sampler.

The United States has not performed a soft landing on the Moon since 1972 when Apollo 17 delivered astronauts Gene Cernan and Jack Schmitt to the Taurus-Littrow valley. The former USSR last did it in 1976 with the sample return mission Luna 24.

-The Geminid meteor shower is subsiding now as Earth exits a stream of debris from rock comet 3200 Phaethon. Preliminary counts by the International Meteor Organization suggest that the shower peaked on Dec. 14th with more than 100 meteors per hour. Bright moonlight reduced the visibility of many faint meteors. Fortunately, the shower was rich in fireballs like the one here: http://www.spaceweather.com/images20...1_Ashcraft.mp4

Amateur astronomer Thomas Ashcraft recorded the fireball using an all-sky camera and a 61 MHz radio receiver. Watch the movie again and turn up the volume. The soundtrack is the echo of a distant TV transmission bouncing off the ionized trail of the disintegrating meteoroid. "By listening to the radio echoes, I could tell there was a strong display of meteors all through the night," says Ashcraft. "We were lucky that some Geminid fireballs appeared through holes in our cloudy skies."

The shower is subsiding, but it's not over. Earth will be inside the debris stream of 3200 Phaethon for some days to come. Look west during the magic hour before sunrise, and you still could see dozens of Geminids between now and Dec. 16th.

-On Dec. 14, 2013, the network reported 110 fireballs. (67 Geminids, 38 sporadics, 1 December Monocerotid, 3 sigma Hydrids )

December 14, 2013

-The bright gibbous Moon shines in Taurus this evening. Through the glare, can you make out the Pleiades roughly a fist-width to its upper left? Easier is Aldebaran farther to the Moon's lower left. Brighter Capella shines much farther left of the Moon.

-The International Meteor Organization is reporting Geminid rates of more than 100 per hour (ZHR) during the early hours of Dec. 14th. This means the shower is approaching its peak. Check the realtime photo gallery for Geminid photos from around the world. And if it's dark where you are, be alert for meteors!

Real Time Photo Gallery of the Meteor Shower Worldwide: http://spaceweathergallery.com/index.php?title=meteor

Meteor Counts: http://www.imo.net/live/geminids2013/

December 13, 2013

-The Geminid meteor shower should be at its peak tonight, from 9 or 10 p.m. until dawn Saturday morning. The best viewing time is after your local moonset: in the hour before the beginning of morning twilight on the 14th. But bright meteors will show even through the moonlight earlier.

-The eclipsing binary star Algol should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:50 p.m. EST.

-On Dec. 12th, NASA's network of all-sky meteor cameras reported 23 Geminid fireballs over the United States. This sharp uptick in activity signals the official beginning of the 2013 Geminid meteor shower. For the next 2 to 3 days, Earth will pass through a stream of debris from rock comet 3200 Phaethon, producing dozens of meteors per hour flying out of the constellation Gemini. "There is a nice show going on right now," says Bill Cooke, head of NASA's Meteoroid Environment Office.

-The multiple cameras of NASA's fireball network are able to measure the orbits of Geminid meteoroids. This plot shows the orbits of the 39 fireballs recorded so far this week.

-Earth is the blue dot where all the orbits intersect. The purple curve shows the path of Geminid parent 3200 Phaethon.

Forecasters expect the shower to peak on Dec. 13-14 when Earth passes through the busiest part of Phaethon's debris stream. Peak rates could reach 120 meteors per hour. However, glare from the nearly-full Moon could reduce the number of visible meteors 2- to 3-fold. Cooke advises looking during the hours just before local sunrise on Saturday, Dec. 14th. "At that time, the Moon will be below the horizon, improving your chances of seeing the show."

December 12, 2013

-The tiny black shadow of Jupiter's fast-moving moon Io crosses Jupiter's face tonight from 10:02 p.m. EST to 12:17 a.m. EST. Following soon behind is Io itself, transiting from 10:37 p.m. to 12:52 a.m. EST. In a telescope, Io is much less visible on Jupiter's bright face than its shadow is.

-Earth is entering a stream of debris from rock comet 3200 Phaethon, source of the annual Geminid meteor shower. Forecasters expect the shower to peak on Dec. 13-14 with as many as 120 meteors per hour. Lunar interference will be a problem, as glare from the nearly-full Moon reduces the number of visible meteors 2- to 5-fold. You can listen to radar echoes from the Geminids, unaffected by moonlight, on Space Weather Radio. Also, tune into NASA's live web chat about the Geminids on Friday the 13th beginning at 11 pm EST found here: http://www.nasa.gov/connect/chat/gem...l#.UqbCkeIlhiI

-Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented on Spaceweather.com. On Dec. 11, 2013, the network reported 32 fireballs. (15 sporadics, 4 December Monocerotids, 9 Geminids, 4 sigma Hydrids)

December 11, 2013

-Which rises first: bright Jupiter in the east-northeast, or bright Rigel in Orion's foot in the east-southeast? Both come up soon after dark. At the latitudes of New York and Denver (about 40° N), Rigel comes first tonight. As far north as Ottawa and Seattle (about 46° N), Jupiter now leads.

-NASA's Solar Dynamics Observatory is monitoring a large coronal hole in the sun's northern hemisphere. Shown here in an extreme ultraviolet photo taken during the early hours of Dec. 11th, the UV-dark chasm overlies more than 500 billion square kilometers of solar terrain.

-Coronal holes are places in the sun's atmosphere where the magnetic field opens up and allows solar wind to escape. A broad stream of solar wind flowing from this particular coronal hole should reach Earth on Dec. 15-17.

The last time a solar wind stream blew past Earth, on Dec. 7th, the impact sparked Northern Lights in the United States as far south as Montana and Michigan. A repeat performance could be in the offing. High-latitude sky watchers should be alert for auroras early next week.

-The season for noctilucent clouds has begun in the southern hemisphere. NASA's AIM spacecraft is monitoring a vast bank of rippling electric-blue NLCs blanketing almost all of Antarctica. This two week movie chronicles the onset of the clouds in late November and their rapid spread into December.

NLCs are Earth's highest clouds. Seeded by "meteor smoke," they form at the edge of space 83 km above Earth's surface. When sunlight hits the tiny ice crystals that make up these clouds, they glow electric blue.

NLCs appear during summer because that is when water molecules are wafted up from the lower atmosphere to mix with the meteor smoke. That is also, ironically, the time when the upper atmosphere is coldest, allowing the ice crystals of NLCs to form.

In recent years NLCs have intensified. Some researchers believe this is a sign of climate change. One of the greenhouse gases that has become more abundant in Earth's atmosphere since the 19th century is methane. "When methane makes its way into the upper atmosphere, it is oxidized by a complex series of reactions to form water vapor," explains Hampton University Professor James Russell, the principal investigator of AIM."This extra water vapor is then available to grow ice crystals for NLCs."

December 10, 2013

-The eastern (left-hand) side of the Great Square of Pegasus points down at the Moon this evening.

-Earth is entering a stream of debris from rock comet 3200 Phaethon, source of the annual Geminid meteor shower. Forecasters expect the shower to peak on Dec. 13-14 with as many as 120 meteors per hour. Lunar interference will be a problem, as glare from the nearly-full Moon reduces the number of visible meteors 2- to 5-fold. You can listen to radar echoes from the Geminids, unaffected by moonlight, on Space Weather Radio.

December 9, 2013

-First-quarter Moon (exact at 10:12 a.m. EST). This evening the Moon shines just under the dim Circlet of Pisces below the Great Square of Pegasus.

-Jupiter is passing just 15 arcminutes from Delta Geminorum, magnitude 3.5, this evening and tomorrow evening. That's about half a pencil-width at arm's length. (But it's not as close as Jupiter passed by the star on October 4th, while going the other way.)

-Later this month, NASA plans to point the Hubble Space Telescope at Comet ISON to see if anything remains after the comet's death plunge through the sun's atmosphere on Nov. 28th. Note to Hubble: Don't expect to see much. Amateur astronomers are already searching the comet's position and setting hard limits on the brightness of any remains. Consider this image taken on Dec. 8th by Eric Allen of the Observatoire du Cégep de Trois-Rivières in Champlain, Québec. The position of the comet-had it survived-is circled. "I unfortunately have to say that there is nothing down to about magnitude +16.5, not even a small condensation," says Allen. More information about Allen's observing techniques and image processing may be found here.

As Karl Battams of the Naval Research Lab comments in his blog on the Comet ISON Observing Campaign web site: "The evidence appears strong that at some point approaching perihelion Comet ISON likely began to completely fall apart. What remains of ISON now is going to be either just a cloud of dust, or perhaps a few very depleted chunks of nucleus. Either way, it's not going to flare up at this point and we should assume the comet's show is over."

December 8, 2013

-This evening, look to the right of the Moon by less than a fist-width at arm's length for the dim Water Jar asterism of Aquarius. Far lower left of the Moon shines Fomalhaut.

-A high-speed solar wind stream is buffeting Earth's magnetic field, sparking G2-class geomagnetic storms around the poles. When Earth first entered the solar wind stream during the late hours of Dec. 7th, Northern Lights spilled over the Canadian border into several US states. Christopher Griffith sends this snapshot from Pillager, Minnesota. "The auroras were dancing lightly across the sky," says Griffith. "It was quite fantastic and fun to watch despite the temperature being -25 F."

NOAA forecasters estimate a 35% chance of additional geomagnetic storms on Dec. 8th and 9th. High-latitude sky watchers should remain alert for auroras as the solar wind continues to blow.

-Amateur astronomers around the northern hemisphere are reporting activity in the tail of naked-eye Comet Lovejoy (C/2013 R1). In Nagano, Japan, astrophotographer Kouji Ohnishi could see big changes in less than an hour of monitoring. Michael Jäger saw the same "disconnection event" from his observatory in Masenberg, Austria, on Dec. 5th. The disturbance could be caused by a gust of solar wind or perhaps an episode of vigorous outgassing in the comet's core.

Comet Lovejoy is now about as bright as a 4th magnitude star. It is visible to the unaided eye from the countryside and is an easy target for backyard telescopes even in urban areas. Monitoring is encouraged. Comet Lovejoy rises in the east just before the morning sun.

December 7, 2013

-Earliest sunset of the year (near 40° north latitude). The longest night won't come until December 21st at the solstice, and the latest sunrise doesn't happen until January 4th. The reason? Local Apparent Solar Time is shifting with respect to Local Mean Time during this part of the year, an effect caused by the tilt of Earth's axis and the ellipticity of Earth's orbit. Be glad that we use standard time, so you don't have to keep adjusting your clocks to the inconstant Sun like in olden days. Standard time made things simpler for society but complicated things for skywatchers.

-The sun's southern hemisphere is peppered with sunspots, but none of them is strongly flaring. Solar activity remains low. NOAA forecasters estimate a 15% chance of M-class solar flares and a scant 1% chance of X-flares on Dec. 6th.

December 6, 2013

-The waxing crescent Moon hangs high over Venus at dusk, with Alpha and Beta Capricorni now to its lower right.

-Have you noticed an extremely luminous star in the southwest after sunset? That's no star. It's Venus, and tonight it is at its brightest for all of 2013. Only the Moon itself outshines the 2nd planet from the sun.

Astronomers are mourning the loss of Comet ISON, which disintegrated when it flew past the sun on Thanksgiving Day (Nov. 28). Who needs it? There is another comet brightening in the morning sky--naked-eye Comet Lovejoy (C/2013 R1). Martin McKenna sends this report from Northern Ireland: "This morning, the comet was easily visible as a fuzzy star of 4th magnitude with a long straight tail between the constellations Bootes and Hercules." He took this picture using a Canon 450D digital camera.

"I could see 5 degrees of tail with my unaided eye," continues McKenna. "Using the camera the tail was at least 10o long!"

Telescopes and longer exposures reveal much more. A "disconnection event" disrupting the comet's tail on Dec. 5th was recorded. The disturbance could be caused by a gust of solar wind or perhaps an episode of vigorous outgassing in the comet's core.

Monitoring is encouraged. Comet Lovejoy is easy to find before dawn rising in the east before the sun.

December 5, 2013

-The crescent Moon poses about 7° to Venus's upper right in twilight, as shown here. As the sky darkens, look with binoculars for Alpha and Beta Capricorni to the Moon's upper left. Both are double stars for binoculars: Alpha is very easy to resolve, Beta is harder.

-When the sun goes down tonight, step outside and look southwest. The crescent Moon and Venus are converging for a beautiful close encounter. These are the two brightest objects in the night sky and they pop out of the twilight long before the sky fades to black. Erwin Matys and Karoline Mrazek of Project Nightflight photographed the pair converging over the Canary island El Hierro on Dec. 4th.

They'll be even closer together tonight. With less than 10o of arc seperating the two, they would fit together inside the bowl of the Big Dipper.

If you have binoculars or a small telescope, take a closer look at the heavenly bodies. Both are crescents. Like the Moon, Venus has phases and tonight it is 27% illuminated. For comparison, the lunar crescent is half as wide, about 13.5%.

Bonus: This week Venus is at its brightest for 2013, shining almost 200 times brighter than a 1st-magnitude star. That's why it is so easy to see before darkness falls. Look southwest as soon as the sun sets.

December 4, 2013

-The sun's southern hemisphere is peppered with sunspots, but none of them is actively flaring. Solar activity remains low. NOAA forecasters estimate a 25% chance of M-class solar flares and a scant 1% chance of X-flares on Dec. 4th.

-Look for the waxing crescent Moon far lower right of Venus in twilight, as shown here.

-Watch Jupiter's moon Io gradually disappear into eclipse by Jupiter's shadow, just off the planet's western limb, around 10:58 p.m. EST. A small telescope is all you need.

-Earth is entering a stream of debris from rock comet 3200 Phaethon, source of the annual Geminid meteor shower. Our planet is just dipping into the outskirts of the debris zone now, so visual meteor rates are low. Nevertheless, the Canadian Meteor Orbit Radar (CMOR) is starting to pick up echoes from Geminid meteoroids. This Dec. 4th radar map shows a concentration of activity in the constellation Gemini.

"The Geminids, still ten days from their maximum, are very clearly visible in the latest CMOR data," reports Prof. Peter Brown of the University of Western Ontario, which operates the radar.

In the radar map, the Geminid radiant is labeled 'GEM.' A second nearby radiant labeled 'NOO' marks the location of the November omega Orionids, a minor shower that peaks in early December.

The Geminids won't peak until Dec. 13-14 when Earth passes through the core of the debris stream, but Brown thinks observers should start looking now. "Glare from the nearly-full Moon will interfere with the Geminid's maximum in mid-December," he says. "This week, however, the Moon is new. Observers should be starting to see activity from this very strong shower." Observing tip: The best time to look is during the hours between midnight and dawn when the constellation Gemini is high in the sky.

So what REALLY happened to Comet ISON?

Data from more distant STEREO cameras has now reached Earth and has been processed by NASA. The result is a view never before seen on this thread that might be of interest to the group.

http://www.planetary.org/blogs/emily-lakdawalla/2013/12021624-multiple-views-of-comet-ison.html

The blog above gives excellent detail about the science behind Comet ISON's constant dimmings and brightenings. And it all has to do with phase angle. Take a look at the latest videos from STEREO A and B. Notice how much slower Comet ISON looks on STEREO B: This is because the comet is speeding towards STEREO B almost head on.

December 3, 2013

-With no sunspots actively flaring, the Earthside of the sun is quiet. However, two sunspots (AR1908 and AR1909) have 'beta-gamma' magnetic fields that harbor energy for moderately strong eruptions. NOAA forecasters estimate a 25% chance of M-class solar flares on Dec. 3rd.

-The Summer Triangle is still high after dusk in December. Spot Vega, its brightest star, in the west-northwest. The brightest above Vega is Deneb. Look farther to Vega's right for Altair.

-At the end of American Thanksgiving Day when the sun was setting over Sumterville, Florida, Paula Phillips took a break from her meal, stepped outside and saw something odd-a pair of luminous 'Vs' in the deepening twilight.

"I've never seen anything like this before," says Phillips. "I photographed the phenomenon with a simple small Samsung camera."

They're sun halos, caused by sunlight shining through ice crystals. Atmospheric optics expert Les Cowley explains:

"These two ‘V’ shaped halos, one rare and one common, change shape dramatically as the sun climbs," he says. "Near sunrise or sunset is the only time to catch them like this. The lower ‘V’ is an upper tangent arc from horizontal hexagonal prisms of ice. The upper one is a rare sunvex Parry arc from similar crystals that - strangely – are fixed so that two prism faces are always horizontal. In the full-sized image, we also see just a trace of a 22o halo and stretching upwards from the sun a sun pillar."

"I find it odd that I saw this in Florida!" continues Phillips. Yet Florida has ice crystal, too. The atmosphere 5 to 10 km above the Sunshine State is always cold enough for water to freeze.

"Florida and other warm places get plenty of halos-some of them exceedingly rare," says Cowley. "Look for them everywhere, winter and summer."

December 2, 2013

-Mars is passing 1.2° upper left of the 3.6-magnitude star Beta Virginis before dawn this morning and tomorrow morning — a sidelight from the Comet ISON hunt. Look for Mars shining very high in the southeast before dawn gets too bright.

-Following its Thanksgiving Day brush with solar fire, sundiving Comet ISON is now just a cloud of dust. Among experts, a consensus is building that the comet broke apart shortly before perihelion (closest approach to the sun). In the movie, note how rapidly the comet fades just before it vanishes behind the occulting disk of the SOHO coronagraph.

-After perihelion, the comet emerges as a diffuse remnant of its former self. No one knows for sure what is inside that fan-shaped cloud. Possibilities include a small remnant nucleus or a "rubble pile" of furiously vaporizing fragments. By the end of the day on Nov. 28th, Comet ISON was spent.

As of Dec. 2nd, the cloud of debris is no brighter than a star of approximately 8th magnitude. Experienced astrophotographers might be able to capture the comet's fading "ghost" in the pre-dawn sky of early December, but a naked-eye spectacle is out of the question.

-China is about to join the club of nations that have landed on the Moon. On Dec. 1st, China's Chang'e-3 spacecraft blasted off from the Sichuan province in southwest China. It's payload: a six-wheeled, 260-lb rover named the "Jade Rabbit" ("Yutu" in Chinese), which could touch down on the lunar surface as early as Dec. 14th.

-Unlike the soft landings of unmanned spacecraft from the USA and the Soviet Union, Chang'e-3 will be able to survey the landscape first and determine the safest spot. The most likely destination is Sinus Iridum, the Bay of Rainbows.

A Chinese-made nuclear battery will power the rover after it lands on the lunar surface. Using plutonium-238, the battery will last for more than 30 years. The rover also has expandable solar arrays to absorb the sun’s energy during the day and retract at night to cover and protect equipment from temperatures of minus 170 degrees Celsius. Onboard sensors include a ground-probing radar, cameras, and a soil sampler.

Jade Rabbit's name comes a Chinese myth: According to the ancient story, a lady called Chang'e swallowed magic pills, which allowed her to fly to the Moon along with her pet rabbit "Yutu". There she became a goddess, and has been living on the Moon with the white rabbit ever since.

December 1, 2013

-NOAA forecasters estimate a 25% chance of polar geomagnetic storms on Dec. 2nd when a CME might deliver a glancing blow to Earth's magnetic field. High-latitude sky watchers should be alert for auroras.

-John Bortle withdraws his relatively optimistic forecast posted yesterday. He writes,

The comet's appearance only suggests a progressive decline now.
While ISON's photometric behavior up to and around perihelion did seem to mimic that of 1962's impressive Comet Seki-Lines, the failure of ISON's current cloud-like coma to exhibit any area of condensation as the cloud thins, and its fading and growing diffuseness, do not correspond to Seki-Lines' post-perihelion regeneration....

To be similar in behavior with C/Seki-Lines, ISON would be developing an increasingly small, dense, very bright condensation within the coma. Likewise, the intensity and length of the tail(s) would be rapidly growing, just as we saw in the case of 2011 W3 Lovejoy following its perihelion....

Following a 2- to 4-day blind period after the comet leaves spacecraft view, Bortle expects only a "large, low-surface-brightness, diffuse cloud showing just a trace of tail" — in other words a challenge object for skilled astrophotographers and image processers, not visual observers — if anything at all.

-Comet ISON is fading fast as it recedes from the sun. Whatever piece of the comet briefly survived its Thanksgiving Day brush with solar fire is now dissipating in a cloud of dust.

This development makes it unlikely that Comet ISON will put on a good show after it exits the glare of the sun in early December. Experienced astrophotographers might be able to capture the comet's fading "ghost" in the pre-dawn sky, but a naked-eye spectacle is out of the question.

On Nov. 29th, pilot Brian Whittaker tried to catch a first glimpse of Comet ISON from Earth, post-perihelion, from a plane flying 36,000 feet over the Arctic Circle in northern Canada. No luck.

"Ideal viewing conditions from the Arctic revealed no Comet ISON," reports Whittaker. "This negative report is to quench the thirst of other fellow dreamers under cloudy skies or further south. Later I could see that SOHO showed the comet dimming further."

Despite Whittaker's negative result, it is too soon to rule out observations from Earth as the twice-dead comet moves away from the glare of the sun. Meanwhile, NASA's fleet of solar observatory will be tracking the remains. Stay tuned for more images.

November 30, 2013

-A bright CME (coronal mass ejection) blasted away from the farside of the sun during the early hours of Nov. 30th. Although the cloud appears to overrun the comet in movies from SOHO (watch), in fact it probably missed or delivered no more than a glancing blow. That's too bad, because a CME impact could reveal the true nature of Comet ISON's mysterious undead core.

-Comet ISON continues to do the exact opposite of what scientists have forecasted it to do. At 19:54 UT Filip Fratev (Bulgarian Acadamy of Sciences) wrote, "ISON [has] started to fade.... [In] the last four hours it faded by more than 2 magnitudes and obviously is less bright... I estimated the comet to be between 2.6 and 3.1 magnitude now."

Four hours later Karl Battams of the Comet ISON Observing Campaign tweeted, "We can't tell if #ISON is in one piece or many. It's about mag 5 now and fading."

-Which rises first: bright Jupiter in the east-northeast, or bright Rigel in Orion's foot in the east-southeast? Both are up by about 8 p.m. depending on where you live. At the latitudes of the U.S. and southern Canada, Rigel comes first tonight. As far north as Paris (latitude 49°) and points farther north, Jupiter is first.

November 29, 2013

-Cancel the funeral. Comet ISON is back from the dead. Yesterday, Nov. 28th, Comet ISON flew through the sun's atmosphere and appeared to disintegrate before the cameras of several NASA and ESA spacecraft. This prompted reports of the comet's demise. Today, the comet has revived and is rapidly brightening.

-Before the flyby, experts had made many predictions about what might happen to the comet, ranging from utter disintegration to glorious survival. No one predicted both.

Karl Battams of NASA's Comet ISON Observing Campaign says, "[colleague] Matthew Knight and I are ripping our hair out right now as we know that so many people in the public, the media and in science teams want to know what's happened. We'd love to know that too! Right now, here's our working hypothesis:

"As comet ISON plunged towards to the Sun, it began to fall apart, losing not giant fragments but at least a lot of reasonably sized chunks. There's evidence of very large dust in the long thin tail we saw in the [SOHO coronagraph] images. Then, as ISON plunged through the corona, it continued to fall apart and vaporize, losing its coma and tail completely just like sungrazing Comet Lovejoy did in 2011. What emerged from the Sun was a small but perhaps somewhat coherent nucleus that has resumed emitting dust and gas for at least the time being."

Battams emphasizes that it is too soon to tell how big the remnant nucleus is or how bright the resurgent comet will ultimately become. "We have a whole new set of unknowns, and this ridiculous, crazy, dynamic and unpredictable object continues to amaze, astound and confuse us to no end. We ask that you please be patient with us for a couple of days as we analyze the data and try to work out what is happening."

Astrophotographer Babak Tafreshi has edited an HD video that compares views of ISON from both of SOHO's coronagraphs. "It seems the comet could become a naked eye object with several degrees of scattered tail by Dec 2nd or 3rd," he predicts. "It's not the comet of the century for sure, and fainter than the Lovejoy sungrazer in Dec. 2011, but an interesting imaging target is just a few nights away!" His video can be found here; http://vimeo.com/80568171

November 28, 2013

-Comet ISON is brightening rapidly as it plunges into the sun's atmosphere. At closest approach around 1:45 p.m. EST on Nov. 28th (Thanksgiving Day in the USA), the comet will be little more than a million kilometers above the sun's fiery surface. Temperatures around ISON's icy nucleus could rise as high as 5000o F. No one knows if it can survive that kind of baking--but if it does, it could emerge as a splendid naked-eye comet in early December.

Right now, the best views of the comet are coming from the Solar and Heliospheric Observatory (SOHO). Over the course of the animation, Comet ISON brightens by a factor of at least four, and possibly as much as a factor of 10. It easily outshines the 1st-magnitude red giant star Antares to the lower left of the sun.

Researchers have been wondering what might happen if a CME strikes Comet ISON. They might find out before the day is over. As the movie shows, CMEs are billowing away from the sun in all directions. Avoiding a collision will become increasingly difficult as the comet moves closer to active regions on the sun's surface.

During the hours around closest approach, NASA's Solar Dynamics Observatory (SDO) will take high-resolution pictures of the comet flying through the sun's atmosphere. This diagram below illustrates the sequence of events. Usually, SDO points straight at the sun. In this case, however, the observatory is being offset and moved three times to track the speeding comet. SDO images of sungrazing Comet Lovejoy in Dec. 2011 were dramatic. Comet ISON could be even better.

November 27, 2013

-The Earthside of the sun is quiet. NOAA forecasters estimate a slim 1% chance of either M- or X-class solar flares on Nov. 27th. However, there is at least one active region on the farside of the sun which could target Comet ISON when it swings around the farside after Nov. 28th.

-Comet ISON is hurtling toward the sun today at 240,000 mph and, despite the rising heat, the comet appears to be intact. Yesterday, reports of fading spectral lines from the comet's core raised concerns that the icy nucleus might be disintegrating. Current images from NASA and ESA spacecraft, however, show the comet still going strong. Comet ISON has just entered the field of view of the Solar and Heliospheric Observatory (SOHO).

-The comet's entrance coincides with a bright CME racing away from the sun's southwestern limb. Astronomers have been wondering what might happen if a CME strikes Comet ISON. This CME, however, will probably miss. The source of the cloud is a farside active region, which is not directly facing the comet.

-Astronomer Karl Battams of NASA's Comet ISON Observing Campaign urges readers to remember the following: "Comet ISON is a dynamically new sungrazing comet, fresh in from the Oort Cloud, and the last time we saw an object like this was never! Furthermore, a sungrazing comet just days from perihelion has never been studied in this kind of detail - we're breaking new ground! When we factor in your standard 'comets are unpredictable' disclaimer, what we have is a huge recipe for the unknown."

November 26, 2013

-Jupiter's Great Red Spot should cross the planet's central meridian around 11:36 p.m. Eastern Standard Time tonight. The tiny black shadow of Jupiter's moon Io crosses the planet's face from 11:47 p.m. EST to 2:01 a.m. EST.

-By about 2 a.m. Wednesday morning the waning Moon is up in the east with Mars shining to its left. By dawn Wednesday morning, they're high in the southeast.

-Comet ISON is getting all the press, but there is a second comet near the sun as well: Comet Encke. NASA's STEREO-A spacecraft is monitoring both. Click to view an updated movie of the solar wind buffeting two comets. In the movie, which spans a three+ day period from Nov. 20 to Nov. 23, the sun is to the right, off-screen. At first glance, Earth and Mercury appear to be labeled backwards. The strange arrangement is actually correct. This is how the two planets appear from STEREO-A's vantage point over the farside of the sun.

"The dark 'clouds' moving from left to right are density enhancements in the solar wind, and these are what are causing the ripples you see in the comet tails," explains Karl Battams of NASA's Comet ISON Observing Campaign.

The ripples could become even more dramatic if a CME hits the comets. This is Comet ISON's first visit to the sun, but Comet Encke has been here before. In 2007 a CME hit Encke and ripped off its tail. Battams and other researchers hope something similar is about to happen now. "I'd love to see a big CME hit Comet ISON," he says in a story from Science@NASA. Watching the impact could teach researchers new things about CMEs and comets.

November 25, 2013

-Last-quarter Moon (exact at 2:28 p.m. EST). The Moon rises around 1 a.m. tonight. By dawn Tuesday morning it's high in the south, with Regulus to its right and Mars to its lower left.

-As Comet ISON approaches the sun, it is becoming increasingly difficult for observers on Earth to photograph the comet. Indeed, by Nov. 24th it seemed impossible. But it only seemed that way. Working from a high-altitude site in the Canary islands, Juan Carlos Casado successfully imaged Comet ISON on Sunday morning deep inside the rosy glow of dawn. "I took this picture of Comet ISON on Nov. 24th at 6: 25 UT from the Teide Observatory," says Casado. "The comet was over the distant island of Gran Canaria above a sea of clouds about 1 hour before sunrise and only 16° from the sun. The exceptional atmospheric conditions of Teide Observatory allowed me to capture the image."

November 24, 2013

-During dawn Monday and Tuesday mornings, when you're preparing to use binoculars or a telescope to make one last pre-perihelion try for Comet ISON barely above the bright horizon, you'll find Mercury and fainter Saturn shining to the naked eye just 3/4° apart (at the times of dawn in North America). They're well above the spot to look for the comet: by 7° on Monday, 9° on Tuesday.

-In a telescope, Mercury will be a tiny, slightly gibbous disk 5.6 arcseconds in diameter (no bigger than Mars, high in the southeast), while Saturn is dimmer but much larger: 34″ across its rings. They're a nice consolation prize!

-NASA's STEREO-A spacecraft is monitoring Comet ISON as it approaches the sun for a close encounter on Nov. 28th. The latest movie from the spacecraft's Heliospheric Imager captures not only Comet ISON but also Earth, Mercury, and Comet Encke. In the movie, which spans a two day period from Nov. 19 to Nov. 22, the sun is to the right, off-screen. "The dark 'clouds' coming from that direction are density enhancements in the solar wind, and these are what are causing the ripples you see in the comet tails," explains Karl Battams of NASA's Comet ISON Observing Campaign.

Although the two comets seem to be experiencing the same solar wind, their tails ripple differently. "Encke has kind of long waves in the tail, whereas ISON's seems almost like high-frequency puffs," points out Battams.

Appearances notwithstanding, the two comets might be in two different streams of solar wind. "The most likely explanation is that ISON is in a faster stream," he comntinues. "Imagine holding a flag on a slightly breezy day. The flag will waft gently in the breeze. Now imagine holding it in really strong winds. The flag will be rippling violently, but those ripples will be smaller in amplitude."

November 23, 2013

-The eclipsing binary star Algol should be at minimum light, magnitude 3.4 instead of its usual 2.3, for a couple hours centered on 9:06 p.m. Eastern Standard Time. It takes several more hours to fade and to rebrighten.

-A cluster of active sunspots has just rotated off the Earthside of the sun. The remaining sunspots facing Earth are quiet, prompting NOAA forecasters to downgrade the chance of geoeffective flares. The odds of an X-class eruption today are no more than 1%.

November 22, 2013

-JThe waning gibbous Moon is up in the east by about 10 p.m. tonight (depending on where you live). Look above it for bright Jupiter and, to Jupiter's left, Pollux and Castor. To the Moon's right twinkles Procyon. Much farther to the right, brighter Sirius is rising or soon to rise.

-Comet ISON is plunging toward the sun and brightening as it heads for a perilous close encounter on Nov. 28th. Yesterday morning, with the "final countdown" clock at T-7 days, Juan Carlos Casado photographed the sundiver over the Teide Observatory in the Canary Islands

-"The comet is over the distant island of Gran Canaria," he says, "while in the central cloud we can see the planet Mercury. ISON was at the limit of naked-eye visibility, but it was an easy target for my SLR camera with a small telephoto lens (85 mm focal length) on a static tripod and 6 seconds of exposure."

Because Comet ISON is moving into the rosy glow of dawn, it will soon be impossible for cameras on Earth to track it. Fortunately, NASA's fleet of solar spacecraft are able to follow the comet into the glare. NASA's STEREO-A spacecraft has already picked up Comet ISON. In the days ahead, STEREO-B, SOHO and the Solar Dynamics Observatory will join the hunt, providing continuous views all the way to perihelion (closest approach to the sun) on Nov. 28th.

-Because NASA's twin STEREO probes are designed to observe the sun, they can see sundiving comets even when the glare becomes intense. Yesterday, Comet ISON joined Earth, Mercury, and Comet Encke in the field of view of STEREO-A's Heliospheric Imager. "The dark 'clouds' of stuff you see coming from the right are density enhancements in the solar wind, and these are what are causing all the ripples you see in comet Encke's tail," explains Karl Battams of NASA's Comet ISON Observing Campaign. "I can pretty much promise you that we're going to see ISON's tail doing that in a couple of day's time, but on a much larger scale!"

Battams points out another exciting development: Comet Encke and Comet ISON are converging for a photogenic close encounter. "No they're not going to hit each other - in reality they are millions of miles apart - but as seen from the STEREO-A spacecraft, they are going to get very close!" he says. "We are probably a couple of days away from seeing two comets almost side-by-side in that camera, with long tails flowing behind them in the solar wind. To say that such an image will be unprecedented is rather an understatement."

November 21, 2013

-Jupiter is the bright "star" upper left of the Moon late this evening. Although they look close together, Jupiter is currently 1,660 times farther away. And Pollux and Castor, to Jupiter's left and upper left, are 500,000 and 730,000 times farther than Jupiter! (at 34 and 52 light-years, respectively).

-Comet ISON is plunging toward the sun at 140,000 mph (62 km/s). You can almost feel the velocity in this image taken on the morning of Nov. 20th by astronomers using the 0.4 meter telescope at the Observatorio de la Hita in La Puebla de Almoradiel, Toledo, Spain. "The comet looked very bright," report the observing team. "The tail was not as well defined today because of the proximity of morning twilight...but still splendid!!"

The comet is brightening rapidly as it approaches the sun. Experienced observers put ISON's rising magnitude near +4.0, well above the threshold of naked-eye visibility. The problem is, the glare of the sun is brightening even faster. Amateur photography of the comet will be possible for a few more days and, soon, only NASA's fleet of solar observatories will be able to track the sundiver.

-Observationally speaking, the next big event in the timeline of Comet ISON's journey comes on Nov. 21st when the comet enters the field of view of NASA's STEREO-A spacecraft. The Heliospheric Imager on STEREO-A will pick up the comet just as Earth-bound telescopes begin to lose it. In the days that follow, STEREO-B, SOHO and the Solar Dynamics Observatory will join the hunt, providing continuous views of Comet ISON all the way to perihelion (closest approach to the sun) on Nov. 28th.

November 20, 2013

-By late evening the waning Moon is up in the east. It's now part of a long, ragged, roughly horizontal snake. From right to left: Rigel in Orion's foot in the east-southeast, Orion's Belt, Betelgeuse, the Moon, Jupiter, Pollux, and above Pollux, Castor.

-Astronomers working with the TRAPPIST telescope at ESO's La Silla Observatory report that Comet ISON's production of gas and dust surged another six-fold during the early hours of Nov. 19th. This marks the second outburst since Nov. 13th. Experienced observers put the comet's rising magnitude near +4.0, well above the threshold of naked-eye visibility. The problem is, ISON is approaching the sun and becoming increasingly difficult to observe. Shahrin Ahmad of Kuala Lumpur, Malaysia, photographed the comet's green core framed by twilight blue on the morning of Nov. 19th.

-The situation is only going to worsen as the comet plunges toward its Nov. 28th close encounter with the sun. Amateur photography of the comet will be possible for a few more days and, soon, only NASA's fleet of solar observatories will be able to track the sundiver.

November 19, 2013

-After 9 or 10 this evening, you'll find the waning gibbous Moon shining inside a huge quadrilateral: Capella to the Moon's upper left, Aldebaran to the Moon's upper right, Betelgeuse closer to its lower right, and bright Jupiter far to its lower left.

-Today, Nov. 19th, Earth is passing through a narrow stream of debris from Comet Tempel-Tuttle, source of the annual Leonid meteor shower. "The Leonids are showing up nicely in our data from the Canadian Meteor Orbit Radar (CMOR)," reports Peter Brown of the University of Western Ontario. "Rates are only about 10 per hour, but the shower is definitely active, if muted due to moonlight this year!"

-To listen to the meteor shower tonight, visit http://spaceweatherradio.com/

-prawling sunspot AR1897 erupted on Nov. 19th (10:26 UT), producing an X1-class solar flare. NASA's Solar Dynamics Observatory recorded the explosion's extreme ultraviolet flash. Although the sunspot is not directly facing Earth, the flare did affect our planet. Mainly, the UV flash produced a wave of ionization in the upper atmosphere over Europe, Africa and parts of Asia. A brief blackout of HF radio transmissions around the poles might have also occurred. First-look coronagraph data from NASA's STEREO-Ahead probe show a CME emerging from the blast site, but it is probably not heading for Earth.

-On Nov. 19, 2013, the network reported 31 fireballs. (21 sporadics, 10 Leonids) This number is expected to increase tonight with the advent of the Leonid meteor shower. Refer to the meteor tracker for more detailed charts.

November 18, 2013

-This evening look right of the just-past-full Moon for Aldebaran. Later in the evening, Orion rises below them.

-Comet's ISON's recent outburst of activity has done more than simply brighten the comet. Whatever exploded from the comet's core also created a spectacularly-long tail, more than 16 million kilometers from end to end. Scroll down to see the full extent of Comet ISON as photographed on Nov. 17th by Michael Jäger of Ebenwaldhöhe, Austria.

"The tail of the comet stretches more than 7o across the sky," says Jäger. It's almost as wide as the bowl of the Big Dipper.

Physically, ISON's tail is about 12 times wider than the sun. So, when the head of ISON plunges into the sun's atmosphere on Nov. 28th, more than 15 million kilometers of the comet's tail will still be jutting into space behind it.

Because so much gas and dust is spewing from the comet's core, it is impossible to see clearly what caused Comet ISON's outburst on Nov. 13-14. One possibility is that fresh veins of ice are opening up in the comet's nucleus, vaporizing furiously as ISON approaches the sun. Another possibility is that the nucleus has completely fragmented.

"If so, it will still be several days before we know for sure," says Karl Battams, an astronomer with NASA's Comet ISON Observing Campaign. "When comet nuclei fall apart, it’s not like a shrapnel-laden explosion. Instead, the chunks slowly drift apart at slightly different speeds. Given that ISON’s nucleus is shrouded in such a tremendous volume of light-scattering dust and gas right now, it will be almost impossible to determine this for at least a few days and perhaps not until the comet reaches the field of view of NASA's STEREO HI-1A instrument on November 21, 2013. We will have to wait for the chunks to drift apart a sufficient distance, assuming they don't crumble first."

November 17, 2013

-Comet ISON is within 2° of Spica this morning and Monday morning as seen from the Americas. Their closest approach, 1/3°, comes around 1h November 18th Universal Time, good timing for observers in the longitudes of eastern Europe and western Asia.

-Reports of naked-eye sightings of Comet ISON are coming in from around the world. Experienced observers put the comet's magntitude at +5.5 on Nov. 16th. This means it is now fully 10 times brighter than it was only three days ago before the outburst. To the naked eye, ISON appears as a faint smudge of pale green light low in the pre-dawn sky. The view through a telescope is more dramatic. The comet's tail has become a riotous crowd of gaseous streamers stretching more than 3.5 degrees across the sky. Amateur astronomer Waldemar Skorupa sends this picture from Kahler Asten, Germany.

-The tail is so long, he couldn't fit the whole thing in the field of view. How long is it? Comet ISON's tail extends more than 8 million kilometers behind the comet's nucleus. For comparison, that's 21 times the distance between Earth and the Moon.

Because so much gas and dust is spewing from the comet's core, it is impossible to see clearly what caused Comet ISON's outburst on Nov. 13-14. One possibility is that fresh veins of ice are opening up in the comet's nucleus, vaporizing furiously as ISON approaches the sun. Another possibility is that the nucleus has completely fragmented.

"If so, it will still be several days before we know for sure," says Karl Battams, an astronomer with NASA's Comet ISON Observing Campaign. "When comet nuclei fall apart, it’s not like a shrapnel-laden explosion. Instead, the chunks slowly drift apart at slightly different speeds. Given that ISON’s nucleus is shrouded in such a tremendous volume of light-scattering dust and gas right now, it will be almost impossible to determine this for at least a few days and perhaps not until the comet reaches the field of view of NASA's STEREO HI-1A instrument on November 21, 2013. We will have to wait for the chunks to drift apart a sufficient distance, assuming they don't crumble first."

In short, no one knows for sure what is happening to Comet ISON. This could be the comet's death throes--or just the first of many brightening events the comet experiences as it plunges toward the sun for a close encounter on American Thanksgiving Day.

November 16, 2013

-The Moon is almost equally full this evening and tomorrow evening. Tonight, look above the Moon for the leading star or two of Aries glimmering through the moonlight. To the Moon's left are the Pleiades, as shown at right. Much farther left twinkles bright Capella.

-The sunspot number is so high, it is starting to confuse photographers. Consider this story from Beijing, China, on the morning of Nov. 15th: "Beijing is usually very polluted and we often miss seeing the sun rise in the morning," says Shalini Purohit. "Today, however, the morning sky was clear and I decided to take some pictures. When I looked at the image I thought there must be come specks of dust on my lens." In fact, the lens was clean; those specks were sunspots. When the sunspot number is high, so is the chance of flares. NOAA forecasters estimate a 50% chance of M-class flares and a 15% chance of X-flares during the next 24 hours. As Purohit's image shows, at least four of the sun's spots are facing Earth. If any eruptions do occur, they will likely be geoeffective.

November 15, 2013

-The bright star high in the west-northwest after dark this month is Vega, often associated with summer. The brightest star higher above it is Deneb. Farther to Vega's left or lower left is Altair, dimmer than Vega but outshining Deneb. These three form the Summer Triangle, which is sinking lower each week as summer becomes a distant memory.

-Comet ISON has brightened suddenly in the last few days to 5th magnitude as of November 15th — a popsicle comet with a round, sharp-edged, bright green head and a long, thin, dim tail. It's speeding sunward near Spica and Mercury low in the east just before dawn. It passes less than 2° from Spica on the mornings of November 17th and 18th for the Americas, accelerating every day toward its November 28th perihelion and trial by fire. Mike Broussard of Lousiana shot Comet ISON on the morning of November 14th using a 200mm lens on a DSLR.

-These changes (the increase in brightness and riotous emergence of gaseous streamers) could be caused by fresh veins of ice opening up in the comet's nucleus. Rapid vaporization of ice by solar heat is a sure-fire way to boost a comet's visibility. But, as NASA's Comet ISON Observing Campaign states, "we have no idea." The comet's nucleus is hidden from view by a hazy green atmosphere, so events in the interior remain a mystery.

"I have a strong suspicion that this is Comet LINEAR (C/1999 S4) all over again," says Mark Kidger of the ESA's European Space Astronomy Centre in Madrid. In the year 2000, Kidger other astronomers monitored Comet LINEAR as it disintegrated en route to the sun. "The sudden appearance of ISON's gas tail, the increasing fuzziness of its coma, and now this sudden outburst all remind me of C/1999 S4 just before it broke apart."

To reiterate: No one knows what is happening to Comet ISON. This could be the comet's death throes--or just the first of many brightening events the comet experiences as it plunges toward the sun for a close encounter on Thanksgiving Day (Nov. 28th).

November 14, 2013

-Look left of the waxing gibbous Moon after dusk for the two or three leading stars of Aries, lined up more or less horizontally. High above the Moon and perhaps a bit right is the Great Square of Pegasus. The Moon itself inhabits dim Pisces.

-Solar activity has been low for 24+ hours, but the forecast calls for flares. Two large, complex sunspots are transiting the Earthside of the sun with mixed-polarity magnetic fields that harbor energy for strong eruptions. The next big flare will probably come from one of these two circled regions. NOAA forecasters estimate a 60% chance of M-class flares and a 30% chance of X-flares during the next 24 hours. Flares from AR1890 could be particularly geoeffective. Because of the way the sun's magnetic field spirals through interplanetary space, AR1890 is magnetically connected to our planet. Particles accelerated by an explosion there would be guided in our direction, possibly causing a radiation storm around Earth.

November 13, 2013

-Go out very early Thursday morning to try for the four pre-dawn comets while the sky is still moonless. Print out your charts and get everything prepared the evening before. As dawn begins to brighten and you're packing up to go back in, don't miss Mercury rising low in the east-southeast. Mercury, brightening each day, is entering its best dawn showing of 2013.

-Comet ISON is getting all the press, but another comet is outshining the media-favorite by nearly an order of magnitude. Comet Lovejoy (C/2013 R1) is almost 10 times brighter than Comet ISON as it passes just outside the orbit of Earth in mid-November: 3D orbit. Rolando Ligustri took this picture of Comet Lovejoy on November 12th using a remotely-controlled telescope in New Mexico.

-The comet's pale green atmosphere is almost twice as wide as the planet Jupiter, and there are no fewer than three tails streaming behind the comet's nucleus. Sky watchers in dark sky sites say that can now see this lovely comet as a faint smudge using averted vision--no optics required. A telescope is, however, recommended.

-Comet Lovejoy is one of four comets now rising in the east before dawn. The other three are exploding Comet LINEAR X1, sungrazing Comet ISON, and short-period Comet Encke, and the brightest of them all. All four are easy targets for backyard optics. Dates of special interest include Nov. 15-18 when Comet LINEAR X1 passes by the bright star Arcturus, Nov 17-18 when Comet ISON has a close encounter with Spica, and Nov. 18-20 when Comet Encke buzzes Mercury. These stars and planets make excellent naked-eye guideposts for finding the comets. Meanwhile, bright Comet Lovejoy is approaching the Big Dipper; if you can't see it with your unaided eye, a quick scan with binoculars will reveal it.

November 12, 2013

-As evening grows late, catch Sirius for perhaps your first time this season! Look for it rising far below Orion (by about two fist-widths at arm's length), nearly at the place on the horizon where Orion's Belt points. Sirius rises around 10 or 11 p.m. depending on your location.

-Amateur astronomers are getting a better look at Comet ISON as it dives toward the sun for a Nov. 28th close encounter with solar fire. As the heat rises, the comet brightens, revealing new details every day. This photo, taken Nov. 10th by Michael Jäger of Jauerling Austria, shows a beautiful double tail. One tail is the ion tail. It is a thin streamer of ionized gas pushed away from the comet by solar wind. The filamentary ion tail points almost directly away from the sun.

November 11, 2013

-Orion displays itself well up in the east-southeast by 9 or 10 p.m. now (depending on how far east or west you are in your time zone). Far left of Orion is Jupiter, shining brightly on its background of Gemini.

-NOAA forecasters estimate a 60% chance of M-class flares and a 30% chance of X-flares on Nov. 11th. The most likely source is active sunspot AR1890, which has already produced three X-flares since Nov. 5th. In addition, a new flare threat is emerging over the sun's SE limb: Sunspot group AR1895 appears to be big and potent enough to produce some explosions of its own during the next 24 hours.

-Comet ISON is brightening as it approaches the sun. Multiple observers now report that it is a binocular object. "I finally saw Comet ISON for the first time using small binoculars!" says pilot Brian Whittaker. He was flying 38,000 feet over the Mediterranean Sea on Nov. 8th when he took this picture showing where to look. "It was faint, but is predicted to brighten and move each day," he adds. "Exciting! "

"I have made my first confirmed binocular sighting of C/2012 S1 ISON as well," reports Pete Lawrence of Selsey UK on Nov. 9th. "ISON's head appears small and stellar through a pair of 15x70s optics."

-Comet ISON is currently moving through the constellation Virgo low in the eastern sky before dawn. Shining like an 8th magnitude star, it is still too dim for naked eye viewing, but an increasingly easy target for backyard optics. Don't delay, because Comet ISON is plunging toward the sun for a perilous encounter on Nov. 28th. At closest approach, the comet will be deep inside the sun's corona and little more than a million kilometers from the fiery stellar surface. If ISON survives--a big IF--it could emerge from solar fire as a naked-eye comet for northern-hemisphere observers in December. Monitoring is encouraged!

November 10, 2013

-Cassiopeia shines high in the northeast in early evening, with its five-star W pattern standing on end. Look far below it for Capella rising. Far right of Capella is the little Pleiades cluster, with Aldebaran down below it.

-sunspot AR1890 has unleashed another strong flare, an X1-class explosion on Nov. 10th at 05:14 UT. NASA's Solar Dynamics Observatory recorded a bright flash of extreme ultraviolet radiation from the blast site. This is the third X-flare from AR1890 since Nov. 5th, and all three have something in common: brevity. AR1890 tends to produce impulsive flares, peaking sharply in a matter of minutes or less. Often, brief flares do not produce coronal mass ejections (CMEs), but this one could be an exception. A movie of the flare shows a plume of material lifting off the sun shortly after the UV flash. That could be the beginnings of an Earth-directed CME.

November 9, 2013

-Comet ISON is upstaged! Four comets are currently on display for binoculars or small telescopes in the east before the beginning of dawn (for Northern Hemisphere observers). One is Comet ISON, still underperforming at only about 8th magnitude. It starts this week about midway between Mars and Spica and speeds toward Spica daily, to pass it on November 17th and 18th. But ISON is being outdone! Comet 2013 R1 (Lovejoy) "is a humdinger — almost as bright now as Comet ISON was forecast to be," writes S&T's Tony Flanders. "And it's very high in the sky... big, bright, and beautiful in 10×30 binoculars."

-The other two comets, Encke and C/2012 X1 (LINEAR), are fainter. See Tony's article The Other Great Morning Comet, with finder charts for Lovejoy and ISON http://www.skyandtelescope.com/obser...231157211.html. Further details and charts for all four are at http://comets.skyhound.com/.

-And don't delay. Encke is getting very low, and moonlight returns to the just-before-dawn sky after about November 15th.

-First-quarter Moon (exact at 12:57 a.m. EST Sunday morning). The Moon shines at nightfall about midway between Altair far to its upper right and Fomalhaut far to its lower left. It hangs just above the dim pattern of Capricornus.

November 8, 2013

-The Hubble Space Telescope has spotted a strange asteroid with six comet-like tails. Researchers think the asteroid, named P/2013 P5, is spewing jets of dust as it rapidly rotates to the breaking point. The full story from Science@NASA is found here: http://science.nasa.gov/science-news.../07nov_6tails/

-Big sunspot AR1890 is crackling with strong flares. The latest, which peaked on Nov. 8th at 04:32 UT, registered X1 on the Richter Scale of Flares. (Note: Earlier, we underestimated the intensity of this flare as M8.) NASA's Solar Dynamics Observatory recorded a flash of extreme UV radiation from the blast site. This sunspot has a signature: It tends to produce very brief flares. The X1-flare was no exception as it lasted barely a minute. Brevity mitigates Earth-effects, so this intense flare was not strongly geoeffective--at least, not at first. The explosion also hurled a CME into space. The cloud could deliver a glancing blow to Earth's magnetic field on Nov. 10-11, possibly sparking polar geomagnetic storms.

November 7, 2013

-The bulge of the crescent Moon points sunward — but not quite down to Venus in evening twilight. The Moon is currently 5° north of the ecliptic, while Venus is 4° south of it. (In fact, Venus is at its farthest-south declination, –27° 10′, since 1930!)

-AR1890, one of the biggest sunspots of the current solar cycle, has turned almost directly toward Earth. This raises the possibility of geoeffective eruptions in the days ahead. NOAA forecasters estimate a 45% chance of M-class flares and a 10% chance of X-flares on Nov. 7th.

-Comet ISON is now inside the orbit of Earth and racing toward the sun. Last night, astronomer Alberto Quijano Vodniza of Pasto, Colombia, recorded the comet moving through space at 103,000 mph (46 km/s). "The movie shows the comet's motion over 27 minutes," says Vodniza. Watch it again. "We also caught a satellite."

On Nov. 28th, Comet ISON will fly through the sun's atmosphere little more than a million kilometers above the sun's fiery surface. This raises a question: Is Comet ISON racing toward its doom? Astronomer Matthew Knight of the Lowell Observatory thinks the comet might withstand the heat:

"At its closest point to the Sun, the equilibrium temperature approaches 5000 degrees Fahrenheit, hot enough to cause much of the dust and rock on ISON’s surface to vaporize," says Knight. "While it may seem incredible that anything can survive this inferno, the rate at which ISON will likely lose mass is relatively small compared to how big it likely is. Assuming that the comet's nucleus is bigger than about 200 meters in radius (current estimates suggest it is 500-2000 m in radius), it will likely survive. It helps that the comet is moving very fast, about 400 km/s at perihelion, so it will not remain long at such extreme temperatures."

If Comet ISON does survive its encounter with the sun, it could put on a good show for backyard astronomers in the northern hemisphere in December. The next few weeks will tell the tale.

November 6, 2013

-Venus and the crescent Moon are closest this evening. Look for them in the southwest as twilight fades.

-On Nov. 5th at 22:12 UT, the magnetic canopy of sunspot AR1890 erupted, producing a brief but intense X3-class solar flare. NASA's Solar Dynamics Observatory recorded the extreme ultraviolet flash.

-Radiation from the flare caused a surge in the ionization of Earth's upper atmosphere--and this led to a rare magnetic crochet. Alexander Avtanski observed the effect using a homemade magnetometer in San Jose, California. A magnetic crochet is a disturbance in Earth's magnetic field caused by electrical currents flowing in air 60 km to 100 km above our heads. Unlike geomagnetic disturbances that arrive with CMEs days after a flare, a magnetic crochet occurs while the flare is in progress. They tend to occur during fast impulsive flares like this one.

-More eruptions are in the offing. NOAA forecasters estimate a 45% chance of M-class solar flares and a 10% chance of X-flares on Nov. 6th.

November 5, 2013

-In twilight, look southwest for the waxing crescent Moon with Venus more than a fist-width at arm's length to its left, as shown here.

-Big sunspot AR1890 has an increasingly unstable 'beta-gamma-delta' magnetic field that harbors energy for strong explosions. So far the sunspot is quiet, but this could be the calm before the storm. NOAA forecasters estimate a 45% chance of M-class solar flares and a 10% chance of X-flares on Nov. 5th.

-On Sunday morning, Nov. 3rd, the New Moon passed in front of the sun, producing a solar eclipse visible from the east Coast of North America to the western side of Africa. Photographer Ben Cooper experienced the event in a way few people ever have--by racing across the path of totality in a jet airplane. "We used a Falcon 900B jet to intercept this extremely short eclipse with a perpendicular crossing of the eclipse path," Cooper says. He took this picture flying 43,000 feet over the Atlantic Ocean.

-Many eclipse chasers didn't bother chasing this particular eclipse because it was so short--in some places lasting only a matter of seconds. Cooper was among a dozen on board the jet who were determined to experience totality. "There was zero margin for error, with the plane, traveling near 600mph and hitting the eclipse shadow where it touched down on Earth at some 8,000 mph, required to hit a geographic point over the ocean at a precise instant," he says. "We arrived at our destination about 1 second late, so we observed even less of the eclipse than we expected. In total, we got an instantaneous totality of nearly zero seconds!" More about the experience can be read here: http://www.launchphotography.com/Tot...ipse_2013.html

November 4, 2013

-Look high in the northeast after dark for Cassiopeia standing on end. Before the Moon starts to brighten the evening sky in a few days, tour some of Cassiopeia's star clusters and nebulae.

-On Oct. 27th, when the students of Earth to Sky Calculus launched a pair of radiation sensors to the stratosphere onboard a helium balloon, they didn't know what to expect. They re-discovered the Pfotzer Maximum, which is a layer of peak radiation about 20 km above Earth's surface. Take a look at this data plot from the team's space weather balloon and keep reading below for more information. The plot shows a complete profile of ionizing radiation between 2.7 km and 27 km above Earth's surface. Data from their sensor counted X-rays and gamma-rays in the energy range 10.0 KeV to 20.0 MeV. A peak in radiation levels occured in the tropopause-that's the Pfotzer Maximum.

-When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles. With increasing depth in the atmosphere, the primary cosmic radiation component decreases, whereas the secondary radiation component increases. This complex situation results in a maximum of the dose rate at an altitude of ~20 km, the so-called "Pfotzer maximum," named after physicist George Pfotzer who discovered the peak using balloons and Geiger tubes in the 1930s.

November 3, 2013

-Jupiter's moon Io casts its tiny shadow onto Jupiter tonight from 12:39 p.m. Eastern Daylight Time to 1:53 a.m. Eastern Standard Time. (A self-adjusting clock will make the switch at 2:00 a.m. your local daylight time.) Europa disappears into eclipse by Jupiter's shadow just west of the planet around 1:45 a.m. Eastern Daylight Time.

-New Moon (exact at 6:50 a.m. Eastern Standard Time).

-This morning, the New Moon passed in front of the sun, producing a solar eclipse visible from the east Coast of North America to the western side of Africa. In Hampton, Virginia, the eclipse was underway when the morning sun rose over the Atlantic Ocean. "We had a beautiful view of the partially eclipsed sun peeking between the clouds," says photographer Stephen Gagnon who stationed his camera on Buckroe Beach.

-Later, the New Moon covered the entire sun, producing an annular eclipse and then a total solar eclipse visible across the Atlantic and Africa. The narrow path of totality touched several African nations including Gabon, the Congo, Uganda, Kenya, Ethiopia and Somalia.

November 2, 2013

-A partial eclipse of the Sun will be in progress as the Sun rises on Sunday morning for the Eastern Seaboard of North America and points inland. The partial eclipse happens in the daytime on Sunday for Africa, the Middle East, southernmost Europe, and elsewhere. The eclipse is total for a narrow track crossing the Atlantic and Equatorial Africa. You can find some good information here: http://www.skyandtelescope.com/obser...229133421.html

-Daylight-saving time ends at 2 a.m. Sunday morning for most of North America. Clocks fall back an hour. When planning for the sunrise eclipse, be sure that your expected sunrise time and your clocks are both in standard time!

-Sunspot AR1884 is directly facing Earth, and it has a mixed-polarity magnetic field that harbors energy for strong eruptions. On Nov. 1st at 1953 UT the active region unleashed a brief but intense M6-class solar flare. NASA's Solar Dynamics Observatory recorded the extreme ultraviolet flash. Although the flare was aimed directly at Earth, its effect on our planet was minimal--mainly because the duration was so short (less than 1 minute). A brief blackout of HF radio signals might have occured on the daylit side of Earth, while low-frequency navigation signals could have been disrupted for ~tens of minutes. Any such disruptions have since subsided.

-Sunspot AR1884 poses a threat for longer and stronger flares this weekend. NOAA forecasters estimate a 40% chance of M-class flares and a 5% chance of X-class flares on Nov. 2nd and 3rd.

November 1, 2013

-Fomalhaut, the Autumn Star, shines at its highest in the south after dinnertime at this time of year. Fomalhaut is often called "lonely" because it's so far from any other 1st-magnitude star. It's in the bottom right of the Great Water: the enormous expanse of autumn sky filled with dim water-themed constellations.

-As expected, a coronal mass ejection (CME) hit Earth's magnetic field during the early hours of Oct. 31st, Halloween. The impact, however, was not strong enough to spark a geomagnetic storm or widespread auroras. Instead, unexpectedly, auroras appeared before the impact. Observing from Troms, Norway, Chris and Becki Nation photographed this spooky scene on Oct. 30th. "AMAZING display last night!" says Chris. "We had a 360 degree light show. It was absolutely breathtaking and we didn't know which way to point the camera."

Becki adds, "we are a family of 6 utter Aurora Addicts: Chris, Becki, Aurora 10, Oceanna 8, Lyrica 3 and Caspian 1. We are currently planning a 4 month road trip in our camper van to Lapland this season from our home in the south of the UK. Things are about to get very green."

But not right away. The geomagnetic field is expected to be mostly quiet for the next 3 days (Nov. 1 - 3).

October 31, 2013

-Halloween is moonless this year. Spot Venus in the southwest as twilight fades, and Vega very high in the west after dark. Higher above Vega is Deneb. A greater distance to Vega's left, look for Altair.

-Algol, the Demon Star, is at minimum light in eclipse for a couple hours centered on 10:35 p.m. EDT.

-High-latitude sky watchers should be alert for auroras on Halloween. A CME is expected to hit Earth's magnetic field on Oct. 31st, possibly sparking polar geomagnetic storms. In northern Norway, the show got started early with this display on Oct. 30th. "We witnessed a very powerful outburst of auroras with bright colours," says photographer Bjørn Jørgensen of Tromsø. And that was before the CME arrived...

-As Oct. 31st begins, indicators still suggest a CME is approaching Earth. NOAA forecasters expect a G1-class geomagnetic storm when it arrives. Watch for the shock here.

October 30, 2013

-NOAA forcasters estimate a 25% chance of polar geomagnetic storms on Oct. 31st when a CME is expected to hit Earth's magnetic field. It was propelled in our direction by an M4-class flare from sunspot AR1882 on Oct. 28th. High-latitude sky watchers should be alert for auroras on Halloween.

-Consider it a parting shot. Just before sunspot AR1875 rotated over the sun's western limb on Oct. 29th, it unleashed a powerful X2-class solar flare. NASA Solar Dynamics Observatory recorded the explosion's extreme ultraviolet flash.

-X-rays and UV radiation from the flare ionized the top of our planet's atmosphere. Waves of ionization disturbed the normal propagation of radio waves over the Americas and the Pacific, and may have caused an HF communications blackout over the poles.

-The Solar and Heliospheric Observatory (SOHO) recorded a bright CME emerging from the blast site. Given the sunspot's location on sun's western limb, however, it is unlikely the CME will reach our planet. Analysts at NOAA are busy evaluating the possibility of a glancing blow in the days ahead.

October 29, 2013

-Look high in the northeast after dark for Cassiopeia standing on end. With the Moon out of the evening sky, now's a fine time to hunt some of Cassiopeia's star clusters and nebulae.

-As October comes to an end, a series of CMEs will sweep past Earth. The first three are expected to deliver glancing blows on Oct. 28th through Oct. 30th, possibly having little effect. A more direct hit is likely on Oct. 31st when a CME from Earth-facing sunspot AR1882 arrives. It was propelled in our direction by an M4-class flare on Oct. 28th. High-latitude sky watchers should be alert for auroras on Halloween.

-he sun is dotted with spots, and three of them pose a threat for strong eruptions. Today's sunspots most-likely-to-flare are circled in this Oct. 29th image of the sun from NASA's Solar Dynamics Observatory. AR1875, AR1882 and AR1875 have 'beta-gamma-delta' magnetic fields that harbor energy for X-class solar flares. One of these spots in particular, AR1882, is almost directly facing Earth, so any eruptions it unleashes would almost surely be geoeffective. NOAA forecasters estimate a 70% chance of M-class flares and a 35% chance of X-flares on Oct. 29th.

October 28, 2013

-Algol in Perseus, the prototype eclipsing binary star, should be in one of its periodic dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 1:46 a.m. Tuesday morning EDT (10:46 p.m. Monday evening PDT). Algol takes several additional hours to fade and to rebrighten. Use the comparison-star chart at right.

-Through the early morning hours and into dawn Tuesday morning, the waning crescent Moon forms a triangle with Mars and Regulus in the eastern sky — for the second time this month. By dawn it's high in the southeast.

-Earth-orbiting satellites detected an X1-class solar flare from sunspot AR1875 on Oct. 28th at 0203 UT. This is the 3rd X-flare since Oct. 25th, which means solar activity is still high.

October 27, 2013

-Halloween is approaching, and this means that Arcturus, the star sparkling low in the west-northwest in twilight, is taking on its role as "the Ghost of Summer Suns." For several days centered on October 29th every year, Arcturus occupies a special place above your local landscape. It closely marks the spot in your sky where the Sun stood at the same time, by the clock, during warm June and July — in broad daylight, of course. So, in the last days of October each year, you can think of Arcturus as the chilly Halloween ghost of the departed summer Sun.

- On Oct. 20th, amateur astronomers realized that the comet's brightness had increased 100-fold and its morphology resembled that of exploding Comet 17P/Holmes in 2007. Follow-up images in recent nights seem to show jet-like structures in Comet LINEAR X1's expanding atmosphere. Amateur astronomer Nick James of Chelmsford, UK, obtained the data on below Oct. 26th. Another set of images taken by James shows the comet's atmosphere or "coma" expanding over a period of two days. "The coma's diameter is increasing at a rate of 30 arcseconds per day," says James. "At a distance of 2.95 AU this corresponds to 65,000 km/day or a little less than 1 km/s." He made these observations using an 11-inch Celestron telescope. Located in the constellation Coma Berenices, Comet LINEAR X1 rises in the east about an hour before the sun. The low altitude of the comet in morning twilight is a challenge, but because the comet is fairly bright, magnitude +8.5, it is still a relatively easy target for backyard telescopes equipped with digital cameras. Monitoring is encouraged!

October 26, 2013

-Last-quarter Moon (exact at 7:40 p.m. EDT). The Moon rises around midnight or 1 a.m. local time tonight, in dim Cancer below Jupiter and Gemini. To the right of the Moon and Jupiter, Procyon forms a nearly equilateral triangle with them.

-By dawn on Sunday they're all high in the southeast to south, with Procyon now on the bottom and Regulus and Mars off to their lower left.

-New sunspot AR1882 isn't very big, but it is potent. The active region has already unleashed two strong solar flares today: An X1 at 08:01 UT followed by an X2 at 15:07 UT. There is no reason to think this fusillade will end soon, so stay tuned for more flares.

-Electromagnetic radiation from today's X2-class solar flare had a significant effect on Earth's upper atmosphere. As a wave of ionization swept across the dayside of the planet, the normal propagation of shortwave radio signals was scrambled. In Alachua, Florida, electrical engineer Wes Greenman recorded the effects using his own shortwave radio telescope. The results are the animation below.

-During the time that terrestrial shortwave transmissions were blacked out, the sun filled in the gap with a loud radio burst of its own. In New Mexico, amateur radio astronomer Thomas Ashcraft recorded the sounds. "This radio burst was a strong one and might be too intense for headphones," cautions Ashcraft. Here is the link to the audio of what an X-Flare explosion would sound like: caution: Loud. http://www.spaceweather.com/images20...z_Ashcraft.mp3

Solar radio bursts are caused by strong shock waves moving through the sun's atmosphere. (Electrons accelerated by the shock front excite plasma instabilities which, in turn, produce shortwave static.) They are usually a sign that a CME is emerging from the blast site - and indeed this flare produced a very bright CME.

October 25, 2013

-Solar activity is intensifying. New sunspot AR1882, which rotated over the sun's eastern limb earlier today, promptly unleashed an X1-class solar flare, adding to a days-long fusillade of flares already underway from sunspots AR1875 and AR1877. NASA's Solar Dynamics Observatory recorded a bright flash of extreme UV radiation from the X1 flare, which peaked at 08:01 UT on Oct. 25th. There may be more to this flare than meets the eye. Watch this movie below of the sun's entire disk. The X1-flare was bracketed by two erupting magnetic filaments, each located hundreds of thousands of kilometers from AR1882. In other words, the X1 flare might have been just one piece of an interconnected global eruption. More flares are in the offing. There are now three sunspot groups on the Earthside of the sun capable of strong eruptions: AR1875, AR1877 and AR1882. NOAA forecasters estimate a 55% chance of M-flares and a 10% chance of X-flares during the next 24 hours.

-Keep an eye to the low east-northeast for Jupiter rising around 11 or midnight (depending on your location). Castor and Pollux shine to its left. About 45 minutes later, the waning gibbous Moon follows it up. And then once the Moon is well up, look to the Moon's lower right for Procyon.

October 24, 2013

- The Moon rises around 10 or 11 tonight (depending on where you are), with bright Jupiter to its left or lower left. Farther left is Pollux, with Castor above it. By the beginning of dawn Friday morning, they're all high in the south (above Procyon).

-Earth's magnetic field is about to receive a glancing blow from three CMEs observed leaving the Sun between Oct. 20th and 22nd. Forecast models suggest that the three clouds merged en route to Earth, and their combined impact could trigger a mild polar geomagnetic storm on Oct. 24-25. High-latitude sky watchers should be alert for auroras.

-Solar activity is high. On October 24th at 00:30 UT, Earth-facing sunspot AR1877 erupted, producing a powerful M9-class solar flare. The eruption hurled a faint CME into space and it appears to be heading toward Earth. The arrival time is not yet known. More flares are in the offing. Two large sunspots, AR1875 and AR1877, have 'beta-gamma-delta' magnetic fields that harbor energy for strong eruptions. NOAA forecasters estimate a 40% chance of M-flares and a 5% chance of X-flares during the next 24 hours.

October 23, 2013

- Fast-growing sunspot AR1875 has developed a 'beta-gamma-delta' magnetic field that harbors energy strong explosions. NOAA forecasters estimate a 30% chance of M-class solar flares and a 5% chance of X-flares on Oct. 23rd.

-During the early hours of Oct. 22nd, a long filament of magnetism erupted on the sun. The explosion hurled a lopsided CME into space, and a new analysis suggests it could be Earth-directed. The eruption occured squarely on the Earthside of the sun, but the CME is not squarely Earth-directed. The bulk of the ejecta will fly north of the sun-Earth line. Nevertheless, the CME is expected to deliver a glancing blow to Earth's magnetic field on Oct. 24-25. It might even merge with a pair of minor CMEs traveling ahead of it. If so, the combined impact would be more likely to spark a geomagnetic storm. High-latitude sky watchers should be alert for auroras in the nights ahead.

-Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs [brighter than Venus or magnitude -4]. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented on Spaceweather.com. On Oct. 22, 2013, the network reported 38 fireballs. In this diagram of the inner solar system, all of the fireball orbits intersect at a single point - Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue).

October 22, 2013

-Venus (magnitude –4.4) shines brightly in the southwest during dusk, gradually moving higher week by week. Can you still see Antares moving farther to its lower right? In a telescope Venus is nearing dichotomy, when it will appear exactly half-lit.

-Almost 450 million km from Earth, Comet C/2012 X1 (LINEAR) has exploded. Amateur astronomers are reporting a 200-fold increase in the comet's brightness on Oct. 20th, and the comet's atmosphere or "coma" now resembles that of exploding Comet 17P/Holmes in 2007. Using a remotely-controlled 0.5 meter telescope in New Mexico, European observers Ernesto Guido, Martino Nicolini and Nick Howes took this picture of the spherical explosion on Oct 21st.

"The predicted magnitude of the comet, pre-outburst, was about +14," says Guido. "Now it is close to +8.5." This is below the threshold for naked-eye visibility, but bright enough for backyard telescopes equipped with digital cameras.

Prompted by the reports of Guido et al, Romanian amateur astronomer Maximilian Teodorescu observed the comet on Oct. 22nd, confirming its brightness and spherical structure: image. "It looked exactly like Comet Holmes back in 2007," says Teodorescu.

Located in the constellation Coma Berenices, Comet LINEAR X1 rises in the east about an hour before the sun. The low altitude of the comet in morning twilight is a challenge. "I could not see the comet through the eyepiece of my 4.5 inch refracting telescope," adds Teodorescu, "but the camera detected it easily enough." The comet could become brighter in the days ahead as its coma expands. Monitoring is encouraged.

-The Canadian Meteor Orbit Radar (CMOR) is still detecting echoes from Orionid meteors. This means Earth is still inside a stream of debris from the shower's parent comet, Halley. A CMOR sky map made at 04:15 UT on Oct. 22nd shows the Orionid radiant (ORI) clearly active. Forecasters expected the shower to peak on Oct. 21st with about 20 meteors per hour. However, Halley's debris stream is so broad that Orionid activity has spilled into Oct. 22nd. If you're up before sunrise, be alert for meteors!

October 21, 2013

-Lonely Fomalhaut, the Autumn Star, is at its highest in the south around 9 or 10 p.m. this week.

-Earth is passing through a stream of debris from Halley's Comet, source of the annual Orionid meteor shower. Forecasters expect the shower to peak on Monday, Oct. 21st, with about 20 meteors per hour. The best time to look is during the hours before local sunrise when the constellation Orion is high in the sky.

-Lunar interference will be a problem during the peak. All but the brightest Orionids will be wiped out by glare from the waning full Moon. Fortunately there are some bright ones. NASA's All Sky Fireball Network captured this Orionid fireball shining through the moonlight over Georgia on the morning of Oct. 20th: http://www.spaceweather.com/images20...60126A_04A.avi

October 20, 2013

-This week, face southwest soon after dark and look high for Altair. It's the bright eye of Aquila, the Eagle, most of which now hangs down below it. Look to Altair's upper left, by about a fist and a half at arm's length, for little Delphinus, the Dolphin, leaping upward.

-Look almost as far to Altair's upper right for Sagitta, the Arrow, even fainter and smaller.

October 19, 2013

-Look about a fist-width above the Moon this evening for the main stars of little Aries, lined up nearly horizontally.

-As Oct. 18th came to a close, a dusky shadow fell across the southern half of the full Hunter's Moon. It was a faint "penumbral" lunar eclipse. Observing from the Canary islands, Frank A. Rodriguez Ramirez photographed the Moon (left) two hours before and (right) at the moment of maximum eclipse. A penumbral eclipse happens when the Moon passes through the pale outskirts of Earth's shadow. It is much less dramatic than a total lunar eclipse. In fact, when observers are not alerted beforehand, they often do not realize an eclipse is underway. Nevertheless, the subtle shadow of Earth is visible to the naked eye if you know it's there.

-Usually when there is a lunar eclipse during a full moon, there is a solar eclipse during the subsequent new moon. The trend continues as this lunar eclipse is no exception to the rule - there will be a hybrid solar eclipse on November 3 favouring Africa and the Atlantic Ocean. Depending where you are, in a hybrid eclipse, you will either see an annular eclipse or a total eclipse - the moon will appear large enough eventually to block out all of the sun!

October 18, 2013

-Full Moon. A slight penumbral eclipse of the Moon will be detectable this evening by careful Moon-watchers in the eastern half of North America. The Moon will pass deepest through the pale outer fringe (penumbra) of Earth's shadow around 7:50 p.m. Eastern Daylight Time (EDT). Look for unusual shading on the Moon's south-southeastern side. Weaker shading should be detectable for at least 45 minutes before and after.


-In Europe and Africa, the penumbral eclipse happens in the middle of the night when the Moon is high: centered on 23:50 Universal Time (GMT).

-More cosmic shadow action! A double shadow transit takes place on Jupiter tonight from 6:25 to 8:37 UT October 19th (2:25 to 4:37 a.m. Eastern Daylight Time Saturday morning). Both Io and Europa will be casting their tiny black shadows onto the planet's face at once. Both shadows leave Jupiter's western edge almost simultaneously — just as Europa itself is beginning to cross in front of Jupiter's eastern edge.

-During this, Jupiter's Great Red Spot is in view. It should cross the planet's central meridian around 3:25 a.m. EDT Sunday morning.

October 17, 2013

-The bright, nearly full Moon shines below the bottom corner of the Great Square of Pegasus this evening.

-The next time you board an airplane with a northern flight path, choose the window seat. Photographer David Mayhew settled in next to the starboard wing of a flight from Denver to Iceland on October 14th, and this is what he saw through the glass. "We were somewhere over the Hudson Bay," says Mayhew. "I rested the lens against the window and held a blanket over my head to reduce reflections - got plenty of odd looks from the other passengers!!" NOAA forecasters estimate a 20% chance of polar geomagnetic storms on Oct. 17th. This means there is at least a 1-in-5 chance of a good view for Arctic fliers.

October 16, 2013

-Antares twinkles 1½° below Venus as twilight fades.

-Sunspot AR1865 is crackling with C- and M-class solar flares, at least one every few hours. Stronger flares could be in the offing. The sunspot has an unstable 'beta-gamma-delta' magnetic field that harbors energy for X-class eruptions. By crackling, however, the active region might be "blowing off steam" that prevents a really big blast. NOAA forecasters estimate a mere 1% chance of X-class flares in the next 24 hours.

October 15, 2013

-The upper-right edge of the Great Square of Pegasus points down at the Moon this evening.

-As expected, a CME hit Earth's magnetic field this morning, Oct. 15th @ 10:00 UT. Earth was already surrounded by a gusty stream of solar wind when the CME arrived, so the signature of the CME's impact was almost indiscernable. Nevertheless, Arctic sky watchers got an eyeful. The solar wind stream itself fueled a fine display of auroras.

October 14, 2013

-Mars, the 1st-magnitude star Regulus, and Comet ISON have gathered together in the pre-dawn sky only a few degrees apart. Comet ISON is invisible to the naked eye, but Mars and Regulus are bright enough to see without optics. They form a pretty red-blue "double star" that can lead telescopic observers to the comet.

-October 13th began with an explosion on the sun. At 00:43 UT, sunspot AR1865 erupted, producing an M1-class solar flare and an Earth-directed CME.

October 13, 2013

-Earth is entering the outskirts of a debris stream from Halley's comet, source of the annual Orionid meteor shower. Last night, Oct. 12th, cameras in NASA's All-Sky Fireball Network detected two bright Orionid fireballs over the United States. The shower is expected to peak this year on Oct. 21st with ~20 meteors per hour between local midnight and dawn. An almost-full Moon on peak night will sharply reduce visibility, so watch out for the early Orionids. They might be the only ones you see. The Fireball network is outlined in the map below.

-The zenith star soon after dark (for skywatchers at mid-northern latitudes) is no longer Vega but Deneb. It will remain there for weeks to come, since night is falling earlier and earlier all the time — counteracting the westward turning of the constellations if you observe at nightfall.

October 12, 2013

-Sunspot AR1861 is pointing directly at Earth and crackling with C-class solar flares. Bigger eruptions could be in the offing. The sunspot has a 'beta-gamma-delta' magnetic field that could erupt at any time. NOAA forecasters estimate a 40% chance of M-class flares and a 15% chance of X-flares on Oct. 12th.

-Venus has been approaching much dimmer Antares, which twinkles to Venus's left in the southwest in evening twilight. They're now 4½° apart. They'll pass 1½° from each other on Wednesday.

October 11, 2013

-The Kreutz sungrazer plunged into the sun yesterday - but it did not come out again. The icy visitor from the outer solar system was blasted by solar heat and completely destroyed. SOHO recorded the doomed comet's last moments

-Radio amateurs, have you heard any strange roaring sounds coming from the loudspeakers of your shortwave radios this week? It might have been the sun. "The Sun has been generating Type III solar radio bursts and they appear to be intensifying," reports amateur radio astronomer Thomas Ashcraft of New Mexico. "The strongest burst so far came at 2155 UTC on October 9th." Ashcraft recommends listening to the audio using stereo headphones. "Type III bursts drift downward in frequency," he explains. "In stereo you can hear the burst pass through 28 MHz first on one speaker and then flow through 21 MHz on the other sound speaker."

Type III solar radio bursts are produced by electrons accelerated to high energies (1 to 100 keV) by solar flares. As the electrons stream outward from the sun, they excite plasma oscillations and radio waves in the sun's atmosphere. When these radio waves head in the direction of Earth, they make themselves heard in the loudspeakers of shortwave radios around the dayside of the planet.

More radio bursts could be in the offing. NOAA forecasters estimate a 30% chance of M-class flares and a 5% chance of X-class flares during the next 24 hours.

The audio of the radio burst can be found here: [caution: will get loud]

http://www.spaceweather.com/images2013/10oct13/Sr_Oct092013_2155ut2821_Ashcraft.mp3

October 10, 2013

-Mercury (magnitude –0.1) remains deep in the glow of sunset. About 30 minutes after sunset, use binoculars to look for it 20° lower right of Venus

-Comet ISON is not the only comet diving toward the sun. Another smaller comet is feeling the heat today. Using a coronagraph to block the sun's glare, the Solar and Heliospheric Observatory (SOHO) is monitoring the comet's death plunge. This comet is a member of the Kreutz family. Seen falling into the sun dozens of times each year, Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail.

-Today's sungrazer is probably doomed. The vast majority of Kreutz comets are small (no more than ~10 m wide) and they evaporate completely as they approach the sun. Comet ISON, on the other hand, is large (~0.5 km wide) and widely expected to survive its brush with the sun on Nov. 28th.

-Yesterday, NASA's Juno spacecraft buzzed Earth only 347 miles above our planet's surface. It was a slingshot maneuver designed to gain velocity for Juno's long trip to Jupiter (ETA: 2016). Although the spacecraft was very faint, several amateur astronomers managed to photograph it. The spacecraft is now hurtling away from Earth at 23,500 mph. Bon voyage, Juno! Find Juno Spacecraft photos here: http://spaceweathergallery.com/index.php?title=juno

October 9, 2013

-An interplanetary shock wave, possibly the leading edge of a CME, hit Earth's magnetic field on October 8th at approximately 2015 UT (1:15 pm PDT). The impact sparked a G1-class geomagnetic storm (in progress) and bright auroras around the Arctic Circle. Lana Rupp photographed the "stunning display of color" over Borgarnes, Iceland, during the early hours of Oct. 9th below. Earth is passing through the wake of the CME where a region of high-speed solar wind continues to buffet our planet's magnetic field. NOAA forecasters, who suspect that a second CME might arrive on Oct. 9th, estimate a 65% chance of polar geomagnetic storms during the next 24 hours. High-latitude sky watchers should remain alert for auroras.

-Solar activity is picking up. New sunspot AR1865 erupted this morning (Oct. 9th at 01:48 UT), producing the strongest solar flare in nearly two months. NASA's Solar Dynamics Observatory recorded the M2.8-class eruption: movie. Earth was not in the line of fire, but future eruptions could be geoeffective as the sunspot turns toward our planet in the days ahead.

-Look for Venus far lower right of the Moon during and after twilight. Just 3/4° above Venus is 2nd-magnitude Delta Scorpii.

October 8, 2013

-The Moon shines above Venus in twilight. Depending on where you are in North America, the Moon, Venus, and fainter Antares form a nearly equilateral triangle.

-A minor CME, propelled towarded Earth by a magnetic filament erupting on the sun, could strike our planet's magnetic field during the late hours of Oct. 9th. NOAA forecasters working through the US government shutdown estimate a 30% to 40% chance of polar geomagnetic storms.

October 7, 2013

-During twilight, the waxing crescent Moon shines to the right of Venus. Well to the Moon's lower right, while twilight is still fairly bright, binoculars show Saturn above Mercury.

-Comet ISON is brightening as it approaches the sun. Estimates by experienced observers put the comet between 10th and 11th magnitude. That's too dim to see with the unaided eye, but bright enough for color photography through mid-sized backyard telescopes. Michael Jäger of Weißenkirchen, Austria, observed the comet on Oct. 5th and found that it was green. To image the comet, Jäger combined multiple exposures through red, green, blue, ultraviolet and infrared filters. Details may be found here.

ISON's green color comes from the gases surrounding its icy nucleus. Jets spewing from the comet's core probably contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C2). Both substances glow green when illuminated by sunlight in the near-vacuum of space.

October 6, 2013

-The team flying NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) mission is among the select few at the space agency who have exemptions allowing them to work during the government shutdown. Early this morning, October 6th, they fired LADEE's main engine in a braking maneuver known as the Lunar Orbit Insertion burn. This slowed the spacecraft's velocity enough for it to be captured by the Moon's gravity. This critical burn went flawlessly and LADEE is now in lunar orbit. Two more main engine burns, on October 9 and 12 will adjust LADEE's trajectory, settling it into its commissioning orbit. LADEE is on a mission to study the diaphanous lunar atmosphere, which is mightily affected by space weather.

-Jupiter is at western quadrature this week, 90° west of the Sun in the morning sky. This is when, in a telescope, the western edge of Jupiter is most clearly dimmer than its eastern, more sunward-facing edge.

October 5, 2013

-If you stay up past midnight this weekend, look east-northeast to catch bright Jupiter on the rise. Castor and Pollux are to its left. Much farther to its right, wintry Orion is coming up too.

-Jupiter (magnitude –2.2, in Gemini) rises in the east-northeast around midnight. It blazes high in the southeast by early dawn. About 8° left of it are Castor and Pollux.

-Mars (magnitude 1.6, in Leo) rises around 3 a.m. It glows in the east in early dawn with Regulus below it. Compare their colors! The gap between them shrinks from 6° on the morning of October 5th to 2° on the morning of the 12th. They'll pass a bit less than 1° apart on the morning of the 15th.

-In a telescope, Mars is still just a tiny blob 4.5 arcseconds wide.

-The Earthside of the sun is quiet, but the farside of the sun is not. During the early hours of Oct. 5th, NASA's STEREO-A probe, stationed over the farside, recorded the eruption of a southern hemisphere sunspot. Shortly after 07:30 UT, a coronal mass ejection (CME) flew over the sun's southeastern limb (credit: SOHO). Radio emissions from shock waves in the CME suggest an expansion velocity of about 700 km/s (1.6 million mph), which is fairly typical of CME speeds. If Earth were in the line of fire, we would probably observe bright polar auroras in a few days. However, this CME is heading away from, not toward our planet.

-The active region that produced the blast will rotate onto the Earthside of the sun in about 7 days. If it remains potent, geoeffective solar activity could increase late next week.

October 4, 2013

-Even as the stars begin to come out in twilight, Cassiopeia is already higher now in the northeast than the sinking Big Dipper is in the northwest. And Cassiopeia's broad W pattern is almost standing on end.

-New Moon (exact at 8:35 p.m. EDT).

-Here's some news you might not hear from NASA because, like much of the US government, the space agency is closed. NASA's Juno spacecraft will slingshot past Earth on October 9th for a velocity boost en route to Jupiter. At closest approach the spacecraft will be only 347 miles from Earth as it gains an extra 16,000 mph for the long journey ahead. Update: During the flyby, Juno's science instruments will sample the Earth environment--a practice run for data-taking at Jupiter years from now. Fortunately, commands to activate Juno's sensors were uploaded before the shutdown. The science experiment can proceed. Radio amateurs are encouraged to beam a message to Juno during the flyby. Juno will be listening.

October 3, 2013

-Jupiter is up in the east by midnight or 1 a.m. and climbs higher until dawn Friday morning. Tonight it's just 0.1° from Delta Geminorum, magnitude 3.5 (you may need binoculars). Delta Gem is more than a magnitude brighter than Ganymede, Jupiter's brightest satellite much closer in.

-As Comet ISON passes Mars en route to the sun this week, the comet is still faint. Nevertheless, many experts believe the comet is on track to become a bright sungrazer in late November. Astronomer Ignacio Ferrin of the University of Antioquia Institute of Physics in Colombia disagrees. Ferrin believes Comet ISON is about to disintegrate. The light curve of ISON, he argues, resembles the light curves of other comets that have have fallen apart. If he's right, the "Comet of the Century" could turn into a century-class disappointment.

-A CME hit Earth's magnetic field during the early hours of October 2nd, sparking a G2-class geomagnetic storm. In North America, auroras spilled across the Canadian border into more than a dozen northern-tier US states.

-The storm has subsided now, but it could flare up again. NOAA forecasters estimate a 50% chance of more polar geomagnetic storms as Earth passes through the wake of the CME on Oct. 3rd. NOAA forecasters working through the government shutdown estimated an almost-even 45% chance of polar geomagnetic storms when the CME arrived. The CME justified those relatively high odds, sparking a G2-class geomagnetic storm around the poles.

October 2, 2013

-Have you ever seen the "false dawn," the morning zodiacal light? This is sunlight reflected from interplanetary dust orbiting in the plane of the solar system. The next two weeks offer a fine opportunity for Northern Hemisphere skywatchers.

October 1, 2013

-Now that October is here, the little fall constellation Aries is visible in the east-northeast after dark and all through the evening. Its two or three brightest stars are lined up roughly horizontally, well below the stars of Andromeda.

-Today, October 1st, Comet ISON will fly by Mars at a distance of only 0.07 AU. Red Planet satellites and rovers have a ringside seat for the flyby, and they will be snapping pictures despite a shutdown of the US government. (Apparently, Curiosity has been designated "essential personnel.")

September 30, 2013

-In the eastern dawn Tuesday morning, look for the thin waning crescent Moon forming a triangle with Mars and Regulus, as shown below. Best view: at least an hour before your local sunrise.

-On Sept. 27th, a meteor exploded in the skies above the US midwest. Witnesses report shadows cast upon the ground, unusual sounds, and a swirling contrail marking the aftermath of the blast. "It was the most brilliant fireball that I have ever seen!" reports Angela McClain, who sends this picture from Faith Ranch in Jewett, Ohio.

"The entire landscape lit up," she continues. "I spun around and there it was, a huge, bright green light, streaking across the sky. Even when it was gone, there was still a bright line in the sky about 20 seconds later. We were all stunned."

"This was a very bright event," says Bill Cooke of NASA's Meteoroid Environment Office. "Flares saturated our meteor cameras, and made determination of the end point (the terminus of the fireball's flight through the atmosphere) virtually impossible. Judging from the brightness, we are dealing with a meter class object."

Data from multiple cameras shows that the meteoroid hit Earth's atmosphere traveling 51 km/s (114,000 mph) and passed almost directly over Columbus, Ohio. Cooke has prepared a preliminary map of the ground track. According to the American Meteor Society, the fireball was visible from at least 14 US states.

September 29, 2013

-Watch a Rocket Launch at 12:00PM EST: http://www.spacex.com/webcast/

With the launch of the hybrid small satellite CASSIOPE, scheduled for 2013, Canada will make a significant contribution to unraveling the mysteries of space weather. To accomplish this feat, the satellite will use a dedicated scientific payload ePOP (enhanced polar outflow probe), which will observe the ionosphere.

-Arcturus is shining ever lower in the west after dusk as autumn proceeds. Some time around 9 p.m., depending on how far east or west you live in your time zone, Arcturus sinks to the same altitude in the west as Capella has risen to in the northeast. How accurately can you time this event? It happens 4 minutes earlier each day.

September 28, 2013

-This is the time of year when, in mid-evening, W-shaped Cassiopeia stands on end halfway up the northeastern sky. And whenever that happens, the dim Little Dipper extends straight leftward from Polaris due north.

-On Sept. 25th, China's experimental Tiangong-1 space station passed directly in front of the sun over Arizona. Mike Weasner held his iPhone 5s up to the eyepiece of a solar-filtered 8" telescope and captured this picture of the spit-second transit.

"The Tiangong-1 space station is about 10 meters by 3 meters in size and was 510.4 kilometers from my observatory at the time of the transit," says Weasner. "The angular diameter of the station was only 4.4 arcsec. Yes, that's small!"

Weasner used CalSky to predict the moment of transit. "I began slo-mo video recording with the iOS 7 Camera app on the iPhone 5s at 095015 MST and continued it for one minute to ensure that I captured the space station," he says. "The Tiangong-1 was successfully imaged on several frames as it crossed the sun's disk."

Most readers are familiar with the 450-ton International Space Station. Fewer may be aware of China's 8.5-ton Tiangong-1 (Heavenly Palace-1). It was launched in Sept. 2011 to establish a foothold in Earth orbit for China's fledgling space program. Since then taikonauts (Chinese astronauts) have visited the Tiangong-1 to practice rendevous and docking procedures and to train for living in space. According to some reports, the Tiangong-1 will be de-orbited in late 2013 to make way for more advanced experimental stations, Tiangong-2 and Tiangong-3 in the years ahead. Ultimately, China hopes to place an Mir-class station in orbit by 2020.

September 27, 2013

-The Moon, a day past last quarter, rises by 1 a.m. tonight (Saturday morning the 28th), with Jupiter shining to its upper left as shown here. Can you spot Delta Geminorum, magnitude 3.6, just ½° below Jupiter?

-For reasons reseachers don't fully understand, auroras love equinoxes. At this time of year, even small gusts of solar wind can spark colorful lights around the poles. On Thursday, the aurora australis appeared over South Arm, Tasmania.

"I captured this image from Betsey Island," says photographer Luke O'Brien. "This is a 30 second exposure at ISO 2500. "

The solar wind blowing past Earth today is relatively slow, only ~350 km/s. As a result, NOAA forecasters estimate a slim 5% chance of polar geomagnetic storms. That might be enough, however, for more equinox auroras.

-The weakest Solar Max in 100 years continues today with another 24 hours of quiet. None of the sunspots on the Earthside of the sun are actively flaring.

September 26, 2013

-Last-quarter Moon tonight (exact at 11:55 p.m. EDT). The Moon rises around 11 or midnight local time, shining in the feet of Gemini. Jupiter is to its lower left, as shown below, and Orion is farther to its right.

-A filament of magnetism curling over the sun's northeastern limb erupted on Sept. 24th around 20:30 UT. NASA's Solar Dynamics Observatory caught the structure hurling part of itself into space. A "canyon of fire" forms as the filament cuts through the sun's lower atmosphere. The glowing walls of the canyon trace the original channel where the filament was suspended by magnetic forces above the stellar surface.

-As erupting magnetic filaments often do, this one launched a coronal mass ejection (CME) into space. The cloud does not appear to be heading for Earth.

September 25, 2013

-The Moon rises late this evening (around 11 p.m. depending on your location), with Aldebaran well to its upper right and brighter Capella farther to its upper left. Earlier, spot these two stars when they're low to judge where the Moon will rise.

-Near the center of the solar disk, growing sunspot AR1850 directly faces Earth. However, like all the other spots on the sun today, AR1850 is quiet and not flaring. The chance of a geoeffective flare today is low.

-Amateur astronomers around the world are photographing Comet ISON as it approaches Mars in the predawn sky. The comet is not as bright as some forecasters expected. What does that mean for ISON's future prospects? The answer may be found below this color photo of the comet obtained by UK astronomer Damian Peach on Sept. 24th. At the moment, Comet ISON is about as bright as a 14th magnitude star, which puts it one or two magnitudes dimmer than forecasts. Nevertheless, according to several experts speaking in a NASA video, Comet ISON is still on track to become an impressive sungrazer. John Bortle predicts ISON will rival Venus during the hours leading up to its closest approach to the Sun in November, while Matthew Knight notes that Comet ISON is brighter than Comet Lovejoy was at the same distance from the sun in 2011. Comet Lovejoy went on to become a spectacular naked-eye object. Comet ISON might do the same. The second comet below is a picture of Comet Lovejoy at its peak, which was only visible to the Southern Hemisphere.

September 24, 2013

-Mercury and Spica are in conjunction just 3/4° apart, very low in the west-southwest in bright twilight. About 20 minutes after sunset, use binoculars to look for them 22° to the lower right of Venus. Mercury is magnitude –0.1. Spica is only a third as bright at magnitude +1.0.

-Today is another day that seems more like Solar Min than Solar Max. All of the sunspots on the Earthside of the sun are quiet, and solar activity is low. NOAA forecasters estimate a slim 5% chance of M-class flares on Sept. 24th.

September 23, 2013

-Altair shines due south very high after dark. It's the leading light of the constellation Aquila, the Eagle. Off the tail of Aquila lies the Scutum Star Cloud, with the grand open cluster M11 just below the dark nebula Barnard 111.

-Comet ISON is falling toward the sun for a close encounter on Thanksgiving Day 2013. If it survives, it could become one of the finest comets in years. At the moment ISON is still far away and faint, but its sunward velocity is impressive--more than 72,000 mph on Sept. 22nd.

Alberto Quijano Vodniza of Pasto, Narino, Colombia, obtained the 35-minute video on Sept 22nd. "The motion of the comet was clearly visible," he says. "I used a 14-inch Celestron telescope and a STL-1001E SBIG camera." The video can be found here: http://spaceweather.com/gallery/indi...pload_id=86998

Comet ISON is now approaching Mars in the eastern sky before sunrise. On Oct. 1st it will fly past the Red Planet at a distance on only 0.07 AU. Mars satellites and rovers are in position to snap the first close-up pictures of the comet.

September 22, 2013

-The September equinox occurs at 4:44 p.m. EDT today, when the Sun crosses the equator heading south for the season. Fall begins in the Northern Hemisphere, spring in the Southern Hemisphere.

-As summer ends, the Sagittarius Teapot moves to the west of south during evening and tips increasingly far over, as if pouring out summer's last drops.

-NASA's Solar Dynamics Observatory is monitoring a coronal hole in the sun's northern hemisphere. It is the UV-dark region in this image taken during the early hours of Sept. 21st. The white lines in the image trace the sun's magnetic field. A coronal hole is a place where the magnetic field spreads apart, allowing solar wind to escape. A stream of solar wind flowing from this particular coronal hole is heading for Earth, due to arrive on Sept. 23-24. Its arrival could add to the impact of a minor CME expected to reach Earth at about the same time. Polar geomagnetic storms are possible early next week.

September 21, 2013

-After the last of twilight has faded away, the Northern Cross in Cygnus floats near the zenith (for skywatchers at mid-northern latitudes). Without looking: Do you know which way its long end points? If you guessed southwest, you're right.

-The September equinox occurs at 4:44 p.m. EDT (20:44 UT) on Sunday, Sept. 22nd, when the Sun crosses the equator heading south. This marks the beginning of autumn in the northern hemisphere and spring in the southern hemisphere. On this date, day and night are of approximately equal length.

You know the equinox is near when you find yourself nearly-blinded while driving down east-west roads. Alan Friedman demonstrates the phenomenon from his hometown in Buffalo, New York. "At the equinoxes, the sun rises due east and sets due west on my street in Buffalo," says Friedman. "One has to drive carefully!"

September 20, 2013

-Saturn is still 4° to the upper right of bright Venus in twilight, as shown here. Watch it move farther from Venus each evening.

-As summer nears its end, orange Antares blinks its bleary seasonal farewell low in the southwest after dusk. The farther north you are, the sooner Antares sinks out of sight.

September 19, 2013

-A winter preview: If you're up before dawn this week, the southern sky displays the same starry panorama as it will at dusk next February. Orion stands high in the south, Sirius and Canis Major sparkle to its lower left, and Gemini, with Jupiter, occupies the high east. Come February, Jupiter will still be there.

-Comet ISON is still more than two months away from its spectacular close encounter with the sun. Amateur astronomers aren't waiting. Observers of Comet ISON will notice that it is in the same part of the sky as Mars. The comet will make a close approach to the Red Planet on October 1st, and during that time Mars satellites will be taking ISON's picture at point blank range. Those images will likely rival or improve upon the view from Earth. Comet ISON is currently not a naked eye object, but Up to date pictures of Comet ISON can be found here: http://spaceweather.com/gallery/inde...et&title2=ison

September 18, 2013

-Full Moon tonight and tomorrow night (exactly full at 7:13 a.m. Thursday morning EDT). The Moon is passing through dim Pisces, to the lower right of the Great Square of Pegasus both evenings.

-Tonight's full Moon is the "Harvest Moon," the full Moon closest to the autumnal equinox. Look for it rising in the east at sunset. Swollen by the Moon illusion and reddened by the effect of low-hanging clouds, the rising Harvest moon is often likened to a "Great Pumpkin."

-After a week of deep quiet, the drowsy sun seems to be waking up. Five new sunspots were numbered on Sept. 17th as the sun hurled a series of coronal mass ejections (CMEs) into space. The Solar and Heliospheric Observatory recorded the expanding clouds. Earth was not in the line of fire of the CMEs. One of them, however, might deliver a glancing blow to our planet's magnetic field a few days hence.

September 17, 2013

-This is the time of year when, as the stars come out, bright Arcturus shines due west at the same height as the Big Dipper hangs in the northwest.

-The sunspot number has dropped to its lowest level of the year. Solitary sunspot AR1841 sits all alone at the center of an otherwise blank solar disk. It is quiet and poses no threat for strong flares.

-NOAA forecasters estimate a scant 1% chance of M- or X-class solar flares during the next 24-48 hours. If the forecast holds, the sun will continue a spate of deep quiet that has lasted for more than a week, nearly-flatlining the sun's x-ray output.

September 16, 2013

-Low in the western twilight, Saturn is now within 4° of brighter Venus. In a telescope at high power they'll be very blurry though the thick atmosphere, but you can certainly observe their wildly different surface brightnesses. Venus is 13 times closer to the Sun than Saturn is, so it's illuminated by sunlight that's about 169 times as bright!

-If you live close to latitude 40° north, Saturn stands straight over Venus on Monday evening.

-NOAA forecasters estimate a 45% chance of polar geomagnetic storms on Sept. 16th in response to an incoming solar wind stream.

September 15, 2013

-At dusk, look southeast high above the Moon for Altair. Lower in the east, the Great Square of Pegasus balances on one corner.

-The quiet from the sun is unlikely to break this weekend. NOAA forecasters estimate a scant 1% chance of M- or X-class solar flares during the next 24-48 hours.

The quiet spell is a bit strange because 2013 is supposed to be a year of solar maximum, with lots of flares and sunspots. Supporting this view are data from NASA-supported observatories which show that the sun's magnetic field is poised to flip - a long-held sign that Solar Max has arrived. Nevertheless, solar activity is low.

One possible explanation is that Solar Max is double-peaked and we are in the valley between peaks. If so, solar activity could surge again in late 2013-2014. No one can say for sure, though. Researchers have been studying sunspots for more than 400 years, and we still cannot predict the behavior of the solar cycle. Continued quiet or stormy space weather? Both are possible in the weeks and months ahead.

September 14, 2013

-Look for bright Vega close to the zenith as twilight fades away, if you live in the world's mid-northern latitudes. Vega goes right through your zenith if you're at latitude 39° north (near Baltimore, Kansas City, Lake Tahoe, Sendai, Beijing, Athens, Lisbon).

-Venus and Saturn (magnitudes –4.1 and +0.7, respectively) are low in the west-southwest in evening twilight, far lower left of Arcturus. They set right after dusk.

-Venus is the brightest but lowest. Saturn slides from Venus's upper left at the beginning of the week to its right or upper right by week's end.

-With the Sun's disk almost completely devoid of sunspots, solar flare activity has come to a halt. Measurements by NOAA's GOES 15 satellite show that the sun's global x-ray emission, a key metric of solar activity, has completely flatlined. The quiet is unlikely to break this weekend. NOAA forecasters estimate a scant 1% chance of M- or X-class solar flares during the next 24-48 hours.

September 13, 2013

-Saturn has closed to within 6° of Venus low in the western twilight, as shown at right. They'll pass 3½° apart on Wednesday and Thursday.

-Researchers have long waited for one of the Voyager probes to leave the solar system. In a surprising turn of events, NASA announced today that Voyager 1 entered interstellar space a whole year ago! This event sets in motion a new era of exploration of the realm between the stars. Full story can be found here: http://science.nasa.gov/science-news...2sep_voyager1/

In February 2012, the National Radio Astronomy Observatory's 5,000-mile-wide Very Long Baseline Array (VLBA) made a radio image of Voyager 1's signal. Little did they know, Voyager 1 was already in interstellar space.

Voyager 1's main transmitter radiates around 22 watts, which is comparable to a typical ham radio or a refrigerator light bulb. Though incredibly weak by the standards of modern wireless communications, Voyager 1's signal is bright when compared to most natural objects studied by radio telescopes.

The image below is about 0.5 arcseconds on a side. An arcsecond is the apparent size of a penny as seen from 2.5 miles (4 kilometers) away. The slightly oblong shape of the image is a result of the array's configuration.

The VLBA made this image of Voyager 1's signal on Feb. 21, 2013. At the time, Voyager 1 was 11.5 billion miles (18.5 billion kilometers) away.

September 12, 2013

-The big but dark-colored asteroid 324 Bamberga is reaching opposition at magnitude 8.1 — an unusually close, once-in-22-years opposition. Seek it out near the Circlet of Pisces.

-European sky watchers are reporting an outburst of September epsilon Perseid meteors. "The outburst occurred around UT midnight on Sept. 9-10," says Bill Cooke, head of NASA's Meteoroid Environment Office. "During a two hour period, meteors appeared at a rate equivalent to ~50 per hour (ZHR). We did not see the outburst in North America because it was still daylight at the time."

NASA all-sky cameras have been recording epsilon Perseid fireballs for days, albeit at a much lower rate than what the Europeans saw. The shower has been active since early September, allowing Cooke's team to calculate orbits for more than a dozen meteoroids.

In the diagram, orbits are color-coded by velocity. Epsilon Perseid meteoroids hit Earth's atmosphere at a "blue-green" speed of about 62 km/s (139,000 mph). According to NASA data, the debris stream appears to be rich in fireball-producing meteoroids.

The epsilon Perseid shower peaks every year around this time, but the shower is not well known because it is usually weak, producing no more than 5 meteors per hour. In 2008 the shower surprised observers with an outburst five times as active, and this year the shower may have doubled even that. Clearly, the epsilon Perseid debris stream contains some dense filaments of material that Earth usually misses but sometimes hits.

No one knows the source of the September epsilon Perseid meteor shower. Whatever the parent is, probably a comet, its orbit must be similar to the green ellipses shown in the orbit-map above. As NASA cameras continue to gather data on this shower, orbital parameters will become more accurately known, possibly leading to a match.

Meanwhile, sky watchers should be alert for more epsilon Perseids in the nights ahead. The shower is waning but still active and more outbursts are possible.

September 11, 2013

-Altair is the brightest star shining high in the south these evenings. Look a finger-width at arm's length to its upper right for fainter Tarazed, a red giant far in Altair's background. Look a little more than a fist to Altair's left or upper left for Delphinus, the leaping Dolphin.

-Sometimes, Earth mimics a supernova, producing a Terrestrial Gamma-ray Flash from the tops of thunderstorms. A new lightning sensor on the International Space Station could solve the mystery of these energetic bursts. http://science.nasa.gov/science-news...p_firestation/

September 10, 2013

-Venus and Saturn (magnitudes –4.1 and +0.7, respectively) hang low in the west-southwest in evening twilight, far lower left of Arcturus. Venus is the brightest but lowest. Saturn glimmers to Venus's upper left, a little closer every day. The star Spica begins the week just under Venus, then moves away to its lower right. Bring binoculars to help with Saturn and Spica.

September 9, 2013

-This evening the Moon in twilight stands off farther left of Saturn, with Venus down to their lower right.

-The face of the sun is nearly blank. There are only two tiny sunspots and neither one is flaring. NOAA forecasters estimate no more than a 1% chance of M- or X-class flares during the next 24 hours.

-Last night, sky watchers in Europe and the Americas witnessed a beautiful conjunction of Venus and the crescent Moon. At closest approach, the two brightest objects in the night sky were less than 1 degree apart. In case you missed it, a similar conjunction will next place next month on Oct. 7-8.

September 8, 2013

-When the sun goes down tonight, step outside and look west. Venus and the slender crescent Moon are gathering in the twilight sky for a beautiful conjunction. Sky watchers across North America will see them only 1o to 3o degrees apart, while observers in far-South America will witness a full-fledged occultation. The Moon will pass directly in front of Venus. It's a nice way to end the day.

September 7, 2013

- While twilight is still bright, use binoculars to look for the thin crescent Moon just above the western horizon to the lower right of Venus and Spica, as shown here.

-Low before dawn, Mars passes through the Beehive star cluster Sunday and Monday mornings.

-NASA's LADEE spacecraft is headed toward the Moon after launching on a Minataur V rocket Friday night from NASA's Wallops Flight Facility in Virginia. The launch, which occured at 11:27 pm EDT, was widely visible along the US east coast from Maine to the Carolinas. Ben Cooper on took the below picture of the rocket flying over the Empire State Building in New York.

-"As seen from the Top of Rockefeller Center, LADEE launches to the moon aboard Orbital Sciences Minotaur V rocket," says Cooper. "[It soared] over the blue-and-green Empire State Building, lit for the US Open of tennis."

-The launch kicks off LADEE's mission to investigate the Moon's atmosphere. Yes, the "airless Moon" has an atmosphere. It is ten thousand billion times thinner than Earth's, but nevertheless there. Apollo astronauts actually saw it with their own eyes.

-LADEE, short for "Lunar Atmosphere and Dust Environment Explorer," will circle the Moon for 100 days to assay the lunar atmosphere. Instruments onboard the spacecraft will look for signs of humidity, electrified dust, and atoms hopping across the lunar surface. A NASA video about LADEE previews the mission.

September 6, 2013

-If you live on the East coast of the US, stay up tonight to witness the rocket plume of a satellite launching into the skies. In most locations, the ascending rocket won't climb more than 10° to 15° above the horizon by the time the third stage shuts down, as the first map below shows. You will need a flat horizon for the event. If you are unable to witness the event for yourself, there is a live stream found here: http://www.nasa.gov/multimedia/nasatv/index.html

-The second map below indicates when you can expect the rocket to be visible in your area.The targeted launch window on September 6, 2013 is from 11:27 - 11:31 PM EDT.

-As evening twilight fades, spot Venus low in the west. Look below it by 2° for little Spica twinkling much fainter. Binoculars help. Saturn glows 13° to Venus's upper left.

September 5, 2013

-As evening twilight fades, spot Venus low in the west. Look below it (by less than 2°) for much fainter little Spica twinkling away. Binoculars help. Saturn glows 14° to their upper left.

-Twice every year, around the time of the equinoxes, Earth can pass directly between the Sun and NASA's Solar Dynamics Observatory (SDO), producing a series of beautiful eclipses from the point of view of the spacecraft. SDO's autumnal eclipse season began this week, producing a partial blackout of the sun. During the eclipse, which was centered around 0658 UT on Sept. 2nd, Earth covered about half of the sun. Because these eclipses typically last for only minutes each day (maximum=72 minutes), there is still plenty of uninterrupted time for SDO to monitor activity on the sun. The ongoing eclipse season will end on Sept. 25th. Below is a youtube video and a picture of such eclipses.

September 4, 2013

-The big but dark-colored asteroid 324 Bamberga has brightened to magnitude 8.3. It's nearly at an unusually close, once-in-22-years opposition. Seek it out on the edge of the Circlet of Pisces.

-Venus (magnitude –4.0) shines brightly low in the west in evening twilight, far below Arcturus. Look a little to its left for much fainter Spica early in the week, then watch Venus close in on Spica every day. It passes less than 2° above Spica on September 5th. Binoculars help. Look too for Saturn about 14° upper left of Spica.

-All of the sunspots on the Earthside of the sun are stable and quiet. NOAA forecasters estimate a slight 5% chance of M-class solar flares and no more than a 1% chance of X-class flares on Sept. 4th.

September 3, 2013

-With the Moon out of the evening sky, now's a good time to see what you can make of the distant galaxy cluster Abell 2666. Its location is easy to find just inside the Great Square of Pegasus. But you'll need a moderately large telescope and a good sky; the cluster's brightest member, giant NGC 7768, appears 12th or 13th magnitude. If you succeed, could this be your record-farthest galaxy? The cluster is 300 million light-years away.

-The Earthside of the sun is quiet and stable today. NOAA forecasters estimate a slim 5% chance of M-class solar flares. The most likely source of an eruption would be sunspot AR1836, which is directly facing Earth.

-A CME expected to hit Earth's magnetic field over the weekend is either late or it hit with such weak impact that solar wind signatures barely show its arrival. Nevertheless, auroras did appear around the Arctic Circle on Sept. 1st and 2nd.

September 2, 2013

-Right after dark at this time of year, bright Vega shines almost straight overhead for skywatchers at mid-northern latitudes. Whenever Vega is highest, it's the sign that rich Sagittarius is at its highest in the south. Work through the Sagittarius area with your charts and scope before it sinks low for the night and the season.

-The Sagittarius Teapot and the surrounding rich Milky Way are highest in the south right after dark at this time of year. The brightest puff of the summer Milky Way seems to rise like steam from the Teapot's spout. All of the labeled objects here and many more are good binocular targets under a dark sky.

-The US Air Force Space Surveillance Radar or "Space Fence" has stopped transmitting. "It appears they pulled the plug at 00:00 UT (6 am Local MDT) on September 1st," reports engineer Stan Nelson, who has been monitoring the radar using an antenna in Roswell, New Mexico. The shutdown is a result of sequester budget cuts by the US Congress. The radar's final echoes came from a Russian satellite and a sporadic meteor. http://spaceweather.com/gallery/indi...pload_id=86224

September 1, 2013

-NOAA forecasters estimate a 70% chance of polar geomagnetic storms on Sept. 1st when a CME is expected to hit Earth's magnetic field. High-latitude sky watchers should be alert for auroras.

-Look east after dark for the Great Square of Pegasus balancing on one corner. Its stars are 2nd and 3rd magnitude. From the Square's left corner runs Andromeda's main line of 2nd-magnitude stars, similarly spaced.

August 31, 2013

-Before dawn Sunday morning, the waning Moon shines inside a quadrilateral of Pollux, Jupiter, Mars, and Procyon, as shown below.

-A coronal mass ejection is expected to hit Earth's magnetic field on Sept. 1st, sparking minor to moderate geomagnetic storms around the poles. The CME was propelled toward Earth by a C8-class flare from sunspot AR1836 on August 30th. High-latitude sky watchers, be alert for auroras!

August 30, 2013

-Before dawn tomorrow morning, Jupiter shines to the left of the waning crescent Moon. They're in Gemini in the east, as shown here. Look for Orion way off to their right.

-NASA's Meteoroid Environment Office has upgraded its estimates of a major fireball that exploded over the southeastern USA on August 28th. Lead researcher Bill Cooke says " the fireball reached a peak magnitude of -13, brighter than a Full Moon, and cast shadows on the ground. This indicates that the meteoroid had a mass of over 50 kg (110 lbs) and was about 40 cm (16 inches) in diameter. It hit the top of Earth's atmosphere traveling 23.7 km/s (53,000 mph)." "As far as I know, this is the brightest event our network has observed in 5 years of operation," he continues. "There are reports of sonic booms reaching the ground, and data from 4 doppler radars indicate that some meteorites may have fallen along the fireball's ground track." (Note: The city in the ground track map is Cleveland, Tennessee, not Cleveland, Ohio.)

-Using data from multiple cameras, Cooke has calculated a preliminary orbit for the meteoroid. The shape and dimensions of the orbit are similar those of a Jupiter-family comet. If meteorites are recovered from the Tennessee countryside, their chemical composition will tell researchers more about the origin of the fireball. A video of the fireball can be found here: http://spaceweather.com/images2013/2...72724B_02A.wmv

August 29, 2013

-Mars and Jupiter shine in the east before and during dawn. Jupiter is the highest and brightest (magnitude –2.0). Look for faint Mars (magnitude +1.6) increasingly far to Jupiter's lower left.

-Above Mars are Pollux and Castor. Off to its right or lower right twinkles Procyon.

-None of the sunspots on the Earthside of the sun is actively flaring. Technically, this means solar activity is "low." Nevertheless, a large magnetic filament in the sun's southern hemisphere erupted during the early hours of August 29th. The CME it hurled into space might have an Earth-directed component.

August 28, 2013

-By about 9 p.m. now (depending on where you live), W-shaped Cassiopeia has risen as high in the northeast as the Big Dipper is in the northwest. Midway between them, and a bit higher, is Polaris. Cassiopeia will grow more ascendant over the Dipper in the coming weeks and months as the seasons turn.

-The interplanetary magnetic field (IMF) inside the solar wind began tilting south on August 27th. This condition often sets the stage for polar geomagnetic storms. High-latitude sky watchers should be alert for auroras after nightfall. The display shown last night was captured by Oskar Pettersson of Luleå, Sweden in the picture shown below.

-Magnetic fields in the sun's northern hemisphere have opened up, creating a hole in the sun's upper atmosphere. The August 27th image below from NASA's Solar Dynamics Observatory shows how solar wind is streaming out of the coronal hole. The solar wind stream is heading for Earth, due to arrive on August 30-31. Its impact will not be a major event. Nevertheless, it could spark geomagnetic storms and auroras at high latitudes. This is good news around the Arctic Circle where the midnight sun is setting. Darkening skies will allow auroras to be seen for the first time in months.

August 27, 2013

-Solar activity is low. All of the sunspots on the Earthside of the sun are either stable or decaying. NOAA forecasters estimate no more than a 1% chance of M-class solar flares during the next 24 hours.

-Last-quarter Moon tonight (exact at 5:35 a.m. Wednesday morning). The Moon rises around 11 or midnight. Once it's well up in the east, look above it for the Pleiades and below it for orange Aldebaran. Well off to their left shines bright Capella.

August 26, 2013

- The Moon rises around 11 p.m. now, about a fist-width at arm's length to the right of the Pleiades.

-Perseus is up in good view in the northeast by late evening. By then you can catch Algol, Beta Persei, near the bottom of one of its eclipses: shining at only magnitude 3.4 instead of its usual 2.1. Mid-eclipse is around 11:54 p.m. EDT (8:54 p.m. PDT). Algol stays this dim for about two hours, and it takes several additional hours to fade and to rebrighten.

-The double-CME expected to hit Earth's magnetic field over the weekend either is late or missed entirely. In Alaska, the Northern Lights appeared anyway.Even without a CME impact, minor fluctuations in the solar wind were enough to ignite auroras around many parts of the Arctic Circle. Thanks to the waning of the summer midnight sun, the lights were visible for the first time in months.

August 25, 2013

-Whenever bright Vega shines highest overhead, as it's doing after dark this week, you know that Sagittarius, rich in deep-sky objects, is at its highest and best in the south. Do your observing here early before the Moon rises around 10.

-NOAA forecasters estimate a 75% chance of polar geomagnetic storms on Aug. 25th in response to an expected CME impact. High-latitude sky watchers should be alert for auroras.

August 24, 2013

-The asteroid 7 Iris (the 7th discovered) is just past opposition in Aquarius.

-The Sagittarius Teapot and the surrounding rich Milky Way are highest in the south right after dark in late August. The brightest puff of the summer Milky Way seems to rise like steam from the Teapot's spout. All of the labeled objects here are good binocular targets under a dark sky.

August 23, 2013

-The Great Square of Pegasus, tipped up on one corner, hangs above the waning gibbous Moon after the Moon rises in mid-evening.

-Mars and Jupiter shine in the east before and during dawn. Jupiter is the highest and brightest (magnitude –2.0). Look for faint Mars (magnitude +1.6) increasingly far to Jupiter's lower left.

August 22, 2013

-After dark, spot Vega overhead and Arcturus in the west. A third of the way down from Vega toward Arcturus is the dim Keystone of Hercules. Two thirds of the way is the dim semicircle of Corona Borealis, the Northern Crown. Corona has only one modestly bright star, Alphecca.

-Two CMEs are heading for Earth. The plasma clouds were expelled from the sun on August 20-21 by a pair of erupting magnetic filaments. NOAA forecasters expect the CMEs to arrive on August 23-24, possibly sparking geomagnetic storms around the poles.

August 21, 2013

-This is the time of year when the Big Dipper scoops down during evening, as if to pick up the water that it will dump from high overhead early next spring. Look northwest.

-As Earth passes through the wake of one CME, which did little to stir geomagnetic activity on Aug. 20th, another CME is on the way. NOAA forecasters expect a coronal mass ejection hurled into space yesterday by an erupting magnetic filament to deliver a glancing blow to Earth's magnetic field on Aug. 23rd. High-latitude sky watchers should be alert for auroras.

August 20, 2013

-The nova peaked a little brighter than magnitude 4.5 early on August 16th, declined slightly, and then has held remarkably steady ever since. It remained a little brighter than magnitude 5.0 from 12h UT August 16th to 18h UT August 18th.

-Full Moon (exact at 9:45 p.m. Eastern Daylight Time). The Moon rises around sunset and shines in dim Aquarius after dark.

-According to NOAA analysts, a CME hurled into space by an M3-class solar flare on August 17th will probably miss Earth. However, Earth will pass through the wake of the CME after the cloud itself passes by. This could trigger polar geomagnetic storms despite the CME being off-target. High-latitude sky watchers should be alert for auroras on August 20-21.

August 19, 2013

-Look east in early dawn for the next few mornings and spot bright Jupiter. Look lower left of Jupiter for faint Mars. Mars forms the bottom end of a curving line with similarly bright Pollux and Castor (to its upper left). Watch this line straighten out day by day as Mars speeds eastward. It becomes exactly straight on Sunday morning the 25th.

August 18, 2013

-The two brightest stars of summer are Vega, passing overhead soon after dark, and Arcturus shining in the west. Vega is a white-hot type-A star 25 light-years away. Arcturus is an orange-yellow-hot type-K giant 37 light-years distant. Both are much brighter than the Sun. Their color difference is pretty clear to the unaided eye.

-Venus (magnitude –4.0) shines brightly low in the west in evening twilight, far below Arcturus. Look to its left and somewhat higher for much fainter Spica, and further on, Saturn. In a telescope Venus is still small (14 arcseconds) and gibbous (78% sunlit).

August 17, 2013

- The waxing gibbous Moon shines in the south after nightfall. Below it is the Sagittarius Teapot, as shown at right.

-Look high to the Moon's upper left for bright Altair. Just above Altair is 3rd-magnitude Tarazed, an orange-red giant star (can you see its tint?) 20 times farther away.

- The nova appears to have peaked a little brighter than magnitude 4.5 on August 16th. It was back down roughly to magnitude 4.8 around 10 p.m. EDT on the 16th (2h August 17th UT).

August 16, 2013

-By about 10 p.m. (depending on where you live), W-shaped Cassiopeia is now as high in the northeast as the Big Dipper is in the northwest. Cassiopeia will grow ever more ascendant over the Dipper for the next several months as the seasons turn.

-The nova discovered in Delphinus on Wednesday brightened to magnitude 5.2 in hardly more than 24 hours. Delphinus is conveniently high in the evening sky. The nova is easy to see in binoculars, and it's faintly visible to the naked eye if you have a dark sky.

August 15, 2013

-Antares is lower right of the Moon this evening.

-The US Air Force Space Surveillance System, a.k.a. the "Space Fence," will be shut down on Oct. 1st. This is a result of automatic cuts imposed by the US Congressional budget sequester. The Space Fence is a multi-station radar deployed across the southern USA capable of tracking satellites, space debris, and meteoroids as far as 30,000 km from Earth. This negatively impacts Space Weather Radio as well, which broadcasts echoes from the Space Fence. In October, spaceweather's radio will shift to a new type of meteor radar based on the forward scattering of VHF TV signals.

August 14, 2013

-Look for orange Antares lower left of the Moon after dusk, with the other stars of upper Scorpius around it. Near the zenith shines the Summer Star, Vega.

-The Perseid meteor shower, which peaked on August 12-13 with as many as 120 meteors per hour, is slowly subsiding as Earth exits the debris stream of parent comet 109P/Swift-Tuttle. Sky watchers should nevertheless remain alert for meteors tonight between midnight and sunrise. It will take several days for the Perseid rate to drop to zero.

August 13, 2013

-The first-quarter Moon shines in the southwest at nightfall, with Saturn to its right and Antares farther to its left. Quite close to the Moon is Alpha Librae, a wide double star for binoculars. The Moon occults (covers) Alpha Librae for much of South America.

-The Perseid meteor shower is underway. Last night, international observers counted more than 120 meteors per hour from dark sky sites. Sky watchers should remain alert for Perseids during the dark hours between midnight and sunrise as Earth passes through the debris stream of parent comet 109P/Swift-Tuttle. According to NASA's Meteoroid Environment Office, the Perseid meteor -shower produces more fireballs than any other annual shower. Last night, Mike Lewinski of Embudo, New Mexico, photographed "the brightest fireball I've ever seen." It was an impressive Perseid, even though he caught only half of it.

-Want to listen to the meteor shower? Use the spaceweather radio here: http://spaceweatherradio.com/

August 12, 2013

-The annual Perseid meteor shower should be at its most active late tonight. (The expected peak time, 2 p.m. EDT August 12th, is ideal for the Far East; for North America it splits the difference between the early morning hours of the 12th and 13th.)

-During and after dusk, spot Saturn above the waxing crescent Moon in the southwest. Look lower right of the Moon for Spica. Much higher to their upper right shines Arcturus.

August 11, 2013

-The annual Perseid meteor shower should be at its most active late tonight and tomorrow night. (The expected peak time, 2 p.m. EDT August 12th, is ideal for the Far East; for North America it splits the difference between the early morning hours of the 12th and 13th.)

-For more information on the Perseids, consult here http://www.skyandtelescope.com/obser...218037521.html

August 10, 2013

-The waxing crescent Moon shines well to the left of Venus low in twilight.

-Look far down to Mars's lower left, as dawn brightens, for Mercury (magnitude —1). It's sinking lower every day. Don't confuse Mercury with Procyon, far down to Mars's lower right.

August 9, 2013

-Early in twilight, about a half hour after sunset, look very low in the west below Venus for the thin crescent Moon, as shown at right. Binoculars will help.

-NOAA forecastesrs estimate a 65% chance of polar geomagnetic storms on August 10th when one and perhaps two CMEs are expected to hit Earth's magnetic field. The incoming clouds were propelled from the sun by a flurry of erupting magnetic filaments on Aug. 6-7. High-latitude sky watchers should be alert for auroras.

-On August 3rd, Japan launched a robotic spacecraft, the HTV-4, to re-supply the International Space Station (ISS). Last night, Larry Sloss saw the HTV-4 in hot pursuit of the ISS in the twilight skies over Priest Lake, Idaho. Many observers noted "HTV-4 flares" this week. Apparently sunlight is glinting off a flat surface of the spacecraft, briefly raising its luminosity to match that of the much larger ISS. HTV-4 has an interesting payload. Among the 5.4 tons of food, spare parts, and other supplies are Kirobo, a talking robot to join the crew of the ISS, and Firestation, an experiment to study mysterious Terrestrial Gamma-ray Flashes. Docking was scheduled at approximately 4:30 AM EDT on Friday August 9th.

August 8, 2013

-The Perseid meteor shower is ramping up! It should peak late this Sunday and Monday nights.

-Saturn (magnitude +0.7, in Virgo) glows in the southwest as twilight fades, with Spica 12° to its lower right. As night grows darker look almost as far to Saturn's left for fainter Alpha Librae.

August 7, 2013

-Bright Vega passes closest to overhead around 10 or 11 p.m., depending on how far east or west you are in your time zone. How closely it misses your zenith depends on how far north or south you live. It passes right through the zenith if you're at latitude 39° north (Washington DC, Cincinnati, Kansas City, Lake Tahoe). How closely can you judge this by looking?

-Yesterday, August 6th, the new Moon passed in front of the sun, producing a partial solar eclipse. The only place to see it was from space. NASA's Solar Dynamics Observatory (SDO) photographed the eclipse from geosynchronous orbit approximately 36,000 km above Earth's surface. Beyond the novelty of observing an eclipse from space, these images have practical value to the SDO science team. The sharp edge of the lunar limb helps researchers measure the in-orbit characteristics of the telescope - e.g., how light diffracts around the telescope's optics and filter support grids. Once these are calibrated, it is possible to correct SDO data for instrumental effects and sharpen the images even more than before.

-Launched on August 3rd, Japan's unmanned HTV-4 cargo carrier is now chasing the International Space Station around Earth. The two spaceships will rendevous on Friday, August 9th. Meanwhile, skywatchers are enjoying the chase. The below picture is from Gary of Fort Davis, Texas when he witnessed a bright flare from the HTV-4 reflecting sunlight.

August 6, 2013

-A binocular challenge: Spot Venus in twilight low in the west and then, using binoculars, see if you can detect the 4.0-magnitude star that it's closely passing. The star is Sigma Leonis, Leo's hind foot, just 0.6° above Venus depending on your time and location.

-New Moon (exact at 5:51 p.m. Eastern Daylight Time).

-Data from NASA-supported observatories show that the sun's global magnetic field will flip before the end of 2013. The reversal, which signals the arrival of Solar Maximum, will have ripple effects felt throughout the solar system.

August 5, 2013

-The little constellation Scutum, off the tail of Aquila, is faint to the naked eye but important for its super-rich Milky Way field and its deep-sky objects. How many can you find?

-Castor and Pollux are to the left of Mercury, Mars and Jupiter, and Orion is much farther to their right.

August 4, 2013

-The asteroid 3 Juno is brightest at opposition this week, glimmering at magnitude 9.0 at the Aquarius-Aquila border.

-Venus (magnitude –3.9) shines brightly very low in the west in evening twilight. In a telescope Venus is still small (13 arcseconds) and gibbous (81% sunlit).

August 3, 2013

-During Sunday dawn an even thinner waning Moon poses to the right of the Jupiter-Mars-Mercury line.

-Magnetic fields in the sun's northern hemisphere have opened up, forming a coronal hole. This UV image from NASA's Solar Dynamics Observatory shows the opening as a dark gap in the sun's upper atmosphere.

August 2, 2013

-Earth is entering a broad stream of debris from comet 109P/Swift-Tuttle, source of the annual Perseid meteor shower. Although the shower won't peak until August 12-13, when Earth hits the densest part of the stream, the first Perseids are already arriving. "Despite poor weather over our network of meteor cameras, we detected three Perseid fireballs on July 30-31," reports Bill Cooke, head of NASA's Meteoroid Environment Office. In the diagram he made below, the green lines trace the orbits of Perseid meteoroids. All three intersect Earth (the blue dot). The orbit of the parent comet is color-coded purple. An inset shows one of the fireballs shining almost as brightly as the Moon.

-The shower is just getting started. Rates should remain low for the next week as Earth penetrates the sparse outskirts of the debris stream, then skyrocket to ~100 meteors per hour as the calendar turns to the second week of August. Stay tuned for more fireballs.

-As summer begins to wane, The Big Dipper hangs diagonally on the wall of the northwestern sky during evening. It's about as high as bright Arcturus, shining left of it in the west.

-In early dawn Saturday morning (you can set your alarm), the waning crescent Moon hangs to the upper right of Jupiter, Mars, and Mercury low in the east-northeast.

August 1, 2013

-The asteroid 3 Juno is brightest at opposition this week, glimmering at magnitude 9.0 at the Aquarius-Aquila border.

-Mercury, Mars, and Jupiter shine low in the east-northeast during dawn. Jupiter is the highest and brightest (magnitude –1.9). Look for faint Mars (magnitude +1.6) a little to Jupiter's lower left. Look below them, and perhaps a bit left, for Mercury, which brightens from magnitude +1 to 0 this week. Best time: about 60 to 40 minutes before your local sunrise. See the illustrations above. Binoculars may help with the fainter two planets, especially through summer haze.

Astro Pic of the Day Archive August 1, 2013 - December 31, 2013

December 31, 2013

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The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the red emission nebula in the center of the above photograph. The horse-head feature is dark because it is really an opaque dust cloud that lies in front of the bright red emission nebula. Like clouds in Earth's atmosphere, this cosmic cloud has assumed a recognizable shape by chance. After many thousands of years, the internal motions of the cloud will alter its appearance. The emission nebula's red color is caused by electrons recombining with protons to form hydrogen atoms. Also visible at the bottom left of the picture is a greenish reflection nebulae that preferentially reflects the blue light from nearby stars.

December 30, 2013

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Gorgeous spiral galaxy M33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies about 3 million light-years distant. Its inner 30,000 light-years are shown in this telescopic galaxy portrait that enhances the reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33's giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. To enhance this image, broadband data was used to produce a color view of the galaxy and combined with narrowband data recorded through a hydrogen-alpha filter, transmitting the light of the strongest hydrogen emission line.

December 29, 2013

http://vimeo.com/21294655

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Sometimes, after your eyes adapt to the dark, a spectacular sky appears. Such was the case in 2011 March when one of the largest auroral displays in recent years appeared over northern locations like the border between Norway and Russia. Pictured in the above time-lapse movie, auroras flow over snow covered landscapes, trees, clouds, mountains and lakes found near Kirkenes, Norway. Many times the auroras are green, as high energy particles strike the Earth's atmosphere, causing the air to glow as electrons resettle into their oxygen hosts. Other colors are occasionally noticeable as atmospheric nitrogen also becomes affected. In later sequences the Moon and rising stars are also visible. With the Sun currently hovering near its time of maximum activity, there may be many opportunities to see similarly spectacular auroras personally, even from areas much closer to the equator.

December 28, 2013

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A remarkably intense auroral band flooded the northern night with shimmering colors on December 7. The stunning sequence captured here was made with a camera fixed to a tripod under cold, clear skies near Ester, just outside of Fairbanks, Alaska. Left to right, spanning a period of about 30 minutes, the panels follow changes in the dancing curtains of northern lights extending to altitudes of over 100 kilometers in a band arcing directly overhead. The panels span 150 degrees vertically, covering about 500 kilometers of aurora laying across the sky from edge to edge. The auroral activity was triggered by a moderate level geomagnetic storm, as a high speed solar wind stream buffeted planet Earth's magnetosphere.

December 27, 2013

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Cosmic clouds seem to form fantastic shapes in the central regions of emission nebula IC 1805. Of course, the clouds are sculpted by stellar winds and radiation from massive hot stars in the nebula's newborn star cluster, Melotte 15. About 1.5 million years young, the cluster stars are near the center of this colorful skyscape, along with dark dust clouds in silhouette. Dominated by emission from atomic hydrogen, the telescopic view spans about 30 light-years. But wider field images reveal that IC 1805's simpler, overall outline suggests its popular name - The Heart Nebula. IC 1805 is located along the northern Milky Way, about 7,500 light years distant toward the constellation Cassiopeia.

December 26, 2013

Source: My Camera
One of the most prominent nebulae in the night sky is M42, the Orion Nebula. Easily visible in plain sight outside of a city, it is the fuzzy middle “star” in Orion’s Sword. It is also the most famous reflection nebula in the sky. Note that, as with most deep-sky objects, the nebula appears gray because our eyes don't perceive colour in dim light. Cameras however, are able to detect the luminous colours found in the region. This particular composite photo is a 55 image stack of the M42 region in order to really bring out as much detail as possible in the nebula. But without an astrotrac or equatorial mount, this is about as sharp an image as I can expect in the attempt to avoid star trails. The photo was taken on a chilly -24C night on December 24, which is ideal for astrophotography because colder nights generally have better seeing conditions, taking away from distortion that the atmosphere may impose on the images.

December 25, 2013

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The graceful arc of the Milky Way begins and ends at two mountain peaks in this solemn night sky panorama. The view was created from a 24 frame mosaic, with exposures tracking Earth and sky separately. In the final composition, northern California's Mount Lassen was positioned at the left and Mount Shasta at the far right, just below the star and dust clouds of the galactic center. Lassen and Shasta are volcanoes in the Cascade Mountain Range of North America, an arc of the volcanic Pacific Ring of Fire. In the dim, snow-capped peaks, planet Earth seems to echo the subtle glow of the Milky Way's own faint, unresolved starlight.

December 24, 2013

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Blown by fast winds from a hot, massive star, this cosmic bubble is huge. Cataloged as Sharpless 2-308 it lies some 5,200 light-years away toward the constellation of the Big Dog (Canis Major) and covers slightly more of the sky than a Full Moon. That corresponds to a diameter of 60 light-years at its estimated distance. The massive star that created the bubble, a Wolf-Rayet star, is the bright one near the center of the nebula. Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. Fast winds from this Wolf-Rayet star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution. The windblown nebula has an age of about 70,000 years. Relatively faint emission captured in the expansive image is dominated by the glow of ionized oxygen atoms mapped to violet hues.

December 23, 2013

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From a radiant point in the constellation of the Twins, the annual Geminid meteor shower rained down on planet Earth over the past few weeks. Recorded near the shower's peak over the night of December 13 and 14, the above skyscape captures Gemini's shooting stars in a four-hour composite from the dark skies of the Las Campanas Observatory in Chile. In the foreground the 2.5-meter du Pont Telescope is visible as well as the 1-meter SWOPE telescope. The skies beyond the meteors are highlighted by Jupiter, seen as the bright spot near the image center, the central band of our Milky Way Galaxy, seen vertically on the image left, and the pinkish Orion Nebula on the far left. Dust swept up from the orbit of active asteroid 3200 Phaethon, Gemini's meteors enter the atmosphere traveling at about 22 kilometers per second.

December 22, 2013

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If you went outside at exactly the same time every day and took a picture that included the Sun, how would the Sun's position change? With great planning and effort, such a series of images can be taken. The figure-8 path the Sun follows over the course of a year is called an analemma. Yesterday, the Winter Solstice day in Earth's northern hemisphere, the Sun appeared at the bottom of the analemma. Analemmas created from different latitudes would appear at least slightly different, as well as analemmas created at a different time each day. With even greater planning and effort, the series can include a total eclipse of the Sun as one of the images. Pictured is such a total solar eclipse analemma or Tutulemma - a term coined by the photographers based on the Turkish word for eclipse. The above composite image sequence was recorded from Turkey starting in 2005. The base image for the sequence is from the total phase of a solar eclipse as viewed from Side, Turkey on 2006 March 29. Venus was also visible during totality, toward the lower right.

December 21, 2013

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Today, the solstice is at 17:11 Universal Time, the Sun reaching the southernmost declination in its yearly journey through planet Earth's sky. The December solstice marks the astronomical beginning of winter in the northern hemisphere and summer in the south. To celebrate, explore this creative visualization of the Sun from visible to extreme ultraviolet wavelengths, using image data from the orbiting Solar Dynamics Observatory (SDO). Against a base image made at a visible wavelengths, the wedge-shaped segments show the solar disk at increasingly shorter ultraviolet and extreme ultraviolet wavelengths. Shown in false-color and rotating in a clockwise direction, the filters decrease in wavelength from 170 nanometers (in pink) through 9.4 nanometers (green). At shorter wavelengths, the altitude and temperature of the regions revealed in the solar atmosphere tend to increase. Bright at visible wavelengths, the solar photosphere looks darker in the ultraviolet, but sunspots glow and bright plasma traces looping magnetic fields. Watch the filters sweep around the solar disk in this animation of SDO's multiwavelength view of the Sun. http://svs.gsfc.nasa.gov/vis/a010000/a011300/a011385/

December 20, 2013

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Saturn's large moon Titan would be unique in our solar system, the only world with stable liquid lakes and seas on its surface ... except for planet Earth of course. Centered on the north pole, this colorized map shows Titan's bodies of methane and ethane in blue and black, still liquid at frigid surface temperatures of -180 degrees C (-292 degrees F). The map is based on data from the Cassini spacecraft's radar, taken during flybys between 2004 and 2013. Roughly heart-shaped, the lake above and right of the pole is Ligeia Mare, the second largest known body of liquid on Titan and larger than Lake Superior on Earth. Just below the north pole is Punga Mare. The sprawling sea below and right of Punga is the (hopefully sleeping) Kraken Mare, Titan's largest known sea. Above and left of the pole, the moon's surface is dotted with smaller lakes that range up to 50 kilometers across.

December 19, 2013

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The Moon is normally seen in subtle shades of grey or yellow. But small, measurable color differences have been greatly exaggerated to make this telescopic, multicolored, moonscape captured during the Moon's full phase. The different colors are recognized to correspond to real differences in the chemical makeup of the lunar surface. Blue hues reveal titanium rich areas while orange and purple colors show regions relatively poor in titanium and iron. The familiar Sea of Tranquility, or Mare Tranquillitatis, is the blue area in the upper right corner of the frame. White lines radiate across the orange-hued southern lunar highlands from 85 kilometer wide ray crater Tycho at bottom left. Above it, darker rays from crater Copernicus extend into the Sea of Rains (Mare Imbrium) at the upper left. Calibrated by rock samples from the Apollo missions, similar multicolor images from spacecraft have been used to explore the Moon's global surface composition.

December 18, 2013

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What's happening behind those houses? Pictured above are not aurora but nearby light pillars, a local phenomenon that can appear as a distant one. In most places on Earth, a lucky viewer can see a Sun-pillar, a column of light appearing to extend up from the Sun caused by flat fluttering ice-crystals reflecting sunlight from the upper atmosphere. Usually these ice crystals evaporate before reaching the ground. During freezing temperatures, however, flat fluttering ice crystals may form near the ground in a form of light snow, sometimes known as a crystal fog. These ice crystals may then reflect ground lights in columns not unlike a Sun-pillar. While going out to buy cat food, a quick thinking photographer, Thomas Kast, captured the above light pillars extending up from bright parking lot lights in Oulu, Finland.

December 17, 2013

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On some nights it rains meteors. Peaking two nights ago, asteroid dust streaked through the dark skies of Earth, showering down during the annual Geminids meteor shower. Astrophotographer Juan Carlos Casado captured the space weather event, as pictured above, in a series of exposures spanning about 2.3 hours using a wide angle lens. The snowcapped Teide volcano of the Canary Islands of Spain towers in the foreground, while the picturesque constellation of Orion highlights the background. The star appearing just near the top of the volcano is Rigel. Although the asteroid dust particles are traveling parallel to each other, the resulting meteor streaks appear to radiate from a single point on the sky, in this case in the constellation of Gemini, off the top of the image. Like train tracks appearing to converge in the distance, the meteor radiant effect is due to perspective. The astrophotographer has estimated that there are about 50 Geminids visible in the above composite image - how many do you see?

December 16, 2013

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A new desk-sized rover has begun exploring the Moon. Launched two weeks ago by the Chinese National Space Administration, the Chang'e 3 spacecraft landed on the Moon yesterday and deployed the robotic rover. Yutu, named for a folklore lunar Jade Rabbit, has a scheduled three-month mission to explore several kilometers inside the Sinus Iridum (Latin for "Bay of Rainbows") impact crater. Yutu's cameras and spectrometers will investigate surface features and composition while ground penetrating radar will investigate deep soil structure. Chang'e 3 achieved the first soft Moon landing since the Soviet Union's Luna 24 in 1976, and Yutu is the first lunar rover deployed since the USSR's Lunokhod 2 in 1973. Pictured above, Yutu was imaged from its lander yesterday soon after rolling onto the Moon.

December 15, 2013

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Although the phase of this moon might appear familiar, the moon itself might not. In fact, this gibbous phase shows part of Jupiter's moon Europa. The robot spacecraft Galileo captured this image mosaic during its mission orbiting Jupiter from 1995 - 2003. Visible are plains of bright ice, cracks that run to the horizon, and dark patches that likely contain both ice and dirt. Raised terrain is particularly apparent near the terminator, where it casts shadows. Europa is nearly the same size as Earth's Moon, but much smoother, showing few highlands or large impact craters. Evidence and images from the Galileo spacecraft, indicated that liquid oceans might exist below the icy surface. To test speculation that these seas hold life, ESA has started preliminary development of the Jupiter Icy Moons Explorer (JUICE), a spacecraft proposed for launch around 2022 that would further explore Jupiter and in particular Europa. Recent observations by the Hubble Space Telescope have uncovered new evidence that Europa, like Saturn's moon Enceladus, has ice venting from its surface.

December 14, 2013

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Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape. Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 10 light-year diameter bubble offers evidence of violent processes at work. Above and right of the Bubble's center is a hot, O star, several hundred thousand times more luminous and around 45 times more massive than the Sun. A fierce stellar wind and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud. The intriguing Bubble Nebula lies a mere 11,000 light-years away toward the boastful constellation Cassiopeia. This natural looking view of the cosmic bubble is composed from narrowband image data, also used to create a 3D model. http://astroanarchy.blogspot.fi/2013...le-nebula.html

December 13, 2013

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The annual Geminid meteor shower is raining down on planet Earth this week. And despite the waxing gibbous moonlight, the reliable Geminids should be enjoyable tonight (night of December 13/14) near the shower's peak. Recorded near last year's peak in the early hours of December 14, 2012, this skyscape captures many of Gemini's lovely shooting stars. The careful composite of exposures was made during a three hour period overlooking the Dashanbao Wetlands in central China. Dark skies above are shared with bright Jupiter (right), Orion, (right of center) and the faint band of the Milky Way. The shower's radiant in the constellation Gemini, the apparent source of all the meteor streaks, lies just above the top of the frame. Dust swept up from the orbit of active asteroid 3200 Phaethon, Gemini's meteors enter the atmosphere traveling at about 22 kilometers per second.

December 12, 2013

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Alnitak, Alnilam, and Mintaka, are the bright bluish stars from east to west (lower right to upper left) along the diagonal in this gorgeous cosmic vista. Otherwise known as the Belt of Orion, these three blue supergiant stars are hotter and much more massive than the Sun. They lie about 1,500 light-years away, born of Orion's well-studied interstellar clouds. In fact, clouds of gas and dust adrift in this region have intriguing and some surprisingly familiar shapes, including the dark Horsehead Nebula and Flame Nebula near Alnitak at the lower right. The famous Orion Nebula itself is off the right edge of this colorful star field. The well-framed, wide-field telescopic image spans about 4 degrees on the sky.

December 11, 2013

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How cold can it get on Earth? In the interior of the Antarctica, a record low temperature of -93.2 °C (-135.8 °F) has been recorded. This is about 25 °C (45 °F) colder than the coldest lows noted for any place humans live permanently. The record temperature occurred in 2010 August - winter in Antarctica - and was found by scientists sifting through decades of climate data taken by Earth-orbiting satellites. The coldest spots were found near peaks because higher air is generally colder, although specifically in depressions near these peaks because relatively dense cold air settled there and was further cooled by the frozen ground. Summer is a much better time to visit Antarctica, as some regions will warm up as high as 15 °C (59 °F).

December 10, 2013

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What will survive this battle of the galaxies? Known as Seyfert's Sextet, this intriguing group of galaxies lies in the head portion of the split constellation of the Snake (Serpens). The sextet actually contains only four interacting galaxies, though. Near the center of this Hubble Space Telescope picture, the small face-on spiral galaxy lies in the distant background and appears only by chance aligned with the main group. Also, the prominent condensation on the upper left is likely not a separate galaxy at all, but a tidal tail of stars flung out by the galaxies' gravitational interactions. About 190 million light-years away, the interacting galaxies are tightly packed into a region around 100,000 light-years across, comparable to the size of our own Milky Way galaxy, making this one of the densest known galaxy groups. Bound by gravity, the close-knit group may coalesce into a single large galaxy over the next few billion years.

December 9, 2013

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Lovejoy continues to be an impressive camera comet. Pictured above, Comet C/2013 R1 (Lovejoy) was imaged above the windmill in Saint-Michel-l'Observatoire in southern France with a six-second exposure. In the foreground is a field of lavender. Comet Lovejoy should remain available for photo opportunities for northern observers during much of December and during much of the night, although it will be fading as the month progresses and highest in the sky before sunrise. In person, the comet will be best viewed with binoculars. A giant dirty snowball, Comet Lovejoy last visited the inner Solar System about 7,000 years ago, around the time that humans developed the wheel.

December 8, 2013

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If you could stand on Mars - what might you see? Scroll right to find out. The robotic Spirit rover that rolled around Mars from 2004 to 2009 Mars climbed to the top of a hill in 2005 and took a series of images over three days that were then digitally combined into a 360 degree panorama. Spirit was instructed to take images having the same resolution as a human with 20-20 eyesight. The full panoramic result can be found by clicking on the above image and has a level of detail unparalleled in the history of Martian surface photography. The panorama was taken from the pinnacle of Husband Hill and has been dubbed the Everest panorama, in honor of the view from the tallest mountain on Earth. Visible in Gusev Crater are rocks, rusting sand, a Martian sundial, vast plains, nearby peaks, faraway peaks, and sand drifts. In the distance, fast moving dust devils can be seen as slight apparitions of red, green, or blue, the colors of filters used to build up this natural color vista.

The full resolution image, if you're willing to load a 22348 pixel long image: http://apod.nasa.gov/apod/image/1312...irit_22348.jpg

December 7, 2013

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Brightest stellar beacons of the constellation Centaurus, Alpha and Beta Centauri are easy to spot from the southern hemisphere. For now, so is new naked eye Nova Centauri 2013. In this night skyscape recorded near Las Campanas Observatory in the Chilean southern Atacama desert on December 5, the new star joins the old in the expansive constellation, seen at early morning hours through a greenish airglow. Caught by nova hunter John Seach from Australia on December 2 as it approached near naked eye brightness, Nova Cen 2013 has been spectroscopically identified as a classical nova, an interacting binary star system composed of a dense, hot white dwarf and cool, giant companion. Material from the companion star builds up as it falls onto the white dwarf's surface triggering a thermonuclear event. The cataclysmic blast results in a drastic increase in brightness and an expanding shell of debris. The stars are not destroyed, though. Classical novae are thought to recur when the flow of material onto the white dwarf eventually resumes and produces another outburst.

December 6, 2013

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For an Earth-orbiting gamma-ray telescope, Earth is actually the brightest source of gamma-rays, the most energetic form of light. Gamma-rays from Earth are produced when high energy particles, cosmic rays from space, crash into the atmosphere. While that interaction blocks harmful radiation from reaching the surface, those gamma-rays dominate in this remarkable Earth and sky view from the orbiting Fermi Gamma-ray Space Telescope's Large Area Telescope. The image was constructed using only observations made when the center of our Milky Way galaxy was near the zenith, directly above the Fermi satellite. The zenith is mapped to the center of the field. The Earth and points near the nadir, directly below the satellite, are mapped to the edges of the field resulting in an Earth and all-sky projection from Fermi's orbital perspective. The color scheme shows low intensities of gamma-rays as blue and high intensities as yellowish hues on a logarithmic scale. Our fair planet's brighter gamma-ray glow floods the edges of field, the high intensity yellow ring tracing Earth's limb. Gamma-ray sources in the sky along the relatively faint Milky Way stretch diagonally across the middle. Launched June 11, 2008 to explore the high-energy Universe, this week Fermi celebrated its 2,000th day in low Earth orbit.

December 5, 2013

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Very faint planetary nebula Abell 7 is some 1,800 light-years distant, just south of Orion in planet Earth's skies in the constellation Lepus, The Hare. Surrounded by Milky Way stars and near the line-of-sight to distant background galaxies, its generally simple spherical shape, about 8 light-years in diameter, is outlined in this deep telescopic image. Within its confines are beautiful, more complex details enhanced by the use of narrowband filters. Emission from hydrogen and nitrogen is shown in reddish hues with oxygen emission mapped to a bluish-green color, giving Abell 7 a more natural appearance that would otherwise be much too faint to be appreciated by eye. A planetary nebula represents a very brief final phase in stellar evolution that our own Sun will experience 5 billion years hence, as the nebula's central, once sun-like star shrugs off its outer layers. Abell 7 itself is estimated to be 20,000 years old. Its central star is seen here as a fading white dwarf some 10 billion years old.

December 4, 2013

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This new comet is quite photogenic. Comet Lovejoy, discovered only three months ago, was imaged through ruins of ancient Mörby Castle in Sweden last week sporting a green-glowing coma and tails trailing several degrees. The past few weeks have been an unusually active time for comet watchers as four comets were visible simultaneously with binoculars: ISON, Lovejoy, Encke, and LINEAR. C/2013 R1 (Lovejoy) comet is currently visible to the unaided eye from a dark location. As Monday's new Moon will provide little glare, the next few days provide a good time to see Comet Lovejoy as it reaches its peak brightness. In two and a half weeks, Comet Lovejoy will reach its closest approach to the Sun at a distance just inside the orbital distance of the Earth.

December 3, 2013

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The many spectacular colors of the Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star Rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light. The Earth's daytime sky appears blue for the same reason. The red and yellow regions shine primarily because of emission from the nebula's atomic and molecular gas. Light from nearby blue stars - more energetic than the bright star Antares - knocks electrons away from the gas, which then shines when the electrons recombine with the gas. The dark brown regions are caused by dust grains - born in young stellar atmospheres - which effectively block light emitted behind them. The Rho Ophiuchi star clouds, well in front of the globular cluster M4 visible above on lower left, are even more colorful than humans can see - the clouds emits light in every wavelength band from the radio to the gamma-ray.

December 2, 2013

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Comet Lovejoy was captured last week passing well in front of spiral galaxy M63. Discovered only three months ago and currently near its maximum brightness, Comet Lovejoy can be seen near the Big Dipper from dark northerly locations before dawn with the unaided eye. An unexpected rival to Comet ISON, C/2013 R1 (Lovejoy), pictured above, is currently sporting a large green coma and a beautifully textured ion tail. Comet Lovejoy is now headed back to the outer Solar System but should remain a good sight in binoculars for another few weeks. Conversely, spiral galaxy M63, lies far in the distance and is expected to remain stationary on the sky and hold its relative brightness for at least the next few million years.

December 1, 2013

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Why are these people shooting a powerful laser into the center of our Galaxy? Fortunately, this is not meant to be the first step in a Galactic war. Rather, astronomers at the Very Large Telescope (VLT) site in Chile are trying to measure the distortions of Earth's ever changing atmosphere. Constant imaging of high-altitude atoms excited by the laser -- which appear like an artificial star -- allow astronomers to instantly measure atmospheric blurring. This information is fed back to a VLT telescope mirror which is then slightly deformed to minimize this blurring. In this case, a VLT was observing our Galaxy's center, and so Earth's atmospheric blurring in that direction was needed. As for inter-galaxy warfare, when viewed from our Galaxy's center, no casualties are expected. In fact, the light from this powerful laser would combine with light from our Sun to together appear only as bright as a faint and distant star.

November 30, 2013

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After failing to appear for Sun staring spacecraft at perihelion, its harrowing closest approach to the Sun, sungrazing Comet ISON was presumed lost. But ISON surprised observers yesterday as material still traveling along the comet's trajectory became visible and even developed an extensive fan-shaped dust tail. Edited and processed to HD format, this video (vimeo, youtube) is composed of frames from the SOHO spacecraft's coronographs. It follows the comet in view of the wide (blue tint) and narrow (red tint) field cameras in the hours both before and after perihelion passage. In both fields, overwhelming sunlight is blocked by a central occulting disk. A white circle indicates the Sun's positon and scale. With questions to be answered and the tantalizing possibility that a small cometary nucleus has survived in whole or part, surprising comet ISON will be rising before dawn in planet Earth's skies in the coming days.

November 29, 2013

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Sungrazing Comet ISON reached perihelion, its closest approach to the Sun, yesterday, November 28, at 18:45 UT. The comet passed just over 1 million kilometers above the solar surface, a distance less than the diameter of the Sun. These two panels follow ISON before (right) and after its close approach, imaged by the LASCO instrument onboard the Sun staring SOHO spacecraft. Overwhelming sunlight is blocked by LASCO's central occulting disk with a white circle indicating the Sun's positon and scale. The bright comet is seen along its path at the bottom of the before panel, but something much fainter exits near the top of the after panel, potentially a dust tail reforming from the debris left from ISON's perihelion passage.

November 28, 2013

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South of the large star-forming region known as the Orion Nebula, lies bright blue reflection nebula NGC 1999. At the edge of the Orion molecular cloud complex some 1,500 light-years distant, NGC 1999's illumination is provided by the embedded variable star V380 Orionis. That nebula is marked with a dark sideways T-shape near center in this cosmic vista that spans about 10 light-years. The dark shape was once assumed to be an obscuring dust cloud seen in silhouette against the bright reflection nebula. But recent infrared images indicate the shape is likely a hole blown through the nebula itself by energetic young stars. In fact, this region abounds with energetic young stars producing jets and outflows with luminous shock waves. Cataloged as Herbig-Haro (HH) objects, named for astronomers George Herbig and Guillermo Haro, the shocks look like red gashes in this scene that includes HH1 and HH2 just below NGC 1999. The stellar jets push through the surrounding material at speeds of hundreds of kilometers per second.

November 27, 2013

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Will Comet ISON survive tomorrow's close encounter with the Sun? Approaching to within a solar diameter of the Sun's surface, the fate of one of the most unusual comets of modern times will finally be determined. The comet could shed a great amount of ice and dust into a developing tail - or break apart completely. Unfortunately, the closer Comet ISON gets to the Sun, the harder it has been for conventional telescopes to see the brightening comet in the glare of the morning Sun. Pictured in the above short time lapse video, Comet ISON was captured rising over the Canary Islands just above the morning Sun a few days ago. If the comet's nucleus survives, the coma and the tails it sheds might well be visible rising ahead of the Sun in the next few days or weeks. Alternatively, satellites watching the Sun might document one of the larger comet disintegrations yet recorded. Stay tuned!

November 26, 2013

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One might say this was a bell weather day for the Sierra Nevada mountains. In January, just as the Sun was setting above the district of Albayzín in Grenada, Spain, a huge cloud appeared as a bell capping the Veleta peak. Such a Cap cloud is formed by air forced upwards by a mountain peak, with the air then cooling, saturating with moisture, and finally having its molecular water condense into cloud droplets. Such a bell-shaped cloud structure is unusual as air typically moves horizontally, making most clouds nearly flat across at the bottom. Vertical waves can also give additional lenticular cloud layers, as also seen above. Given the fleeting extent of the great cloud coupled with momentarily excellent sunset coloring, one might considered this also a bellwether day for an accomplished photographer.

November 25, 2013

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How far away is spiral galaxy NGC 4921? Although presently estimated to be about 310 million light years distant, a more precise determination could be coupled with its known recession speed to help humanity better calibrate the expansion rate of the entire visible universe. Toward this goal, several images were taken by the Hubble Space Telescope in order to help identify key stellar distance markers known as Cepheid variable stars. Since NGC 4921 is a member of the Coma Cluster of Galaxies, refining its distance would also allow a better distance determination to one of the largest nearby clusters in the local universe. The magnificent spiral NGC 4921 has been informally dubbed anemic because of its low rate of star formation and low surface brightness. Visible in the above image are, from the center, a bright nucleus, a bright central bar, a prominent ring of dark dust, blue clusters of recently formed stars, several smaller companion galaxies, unrelated galaxies in the far distant universe, and unrelated stars in our Milky Way Galaxy.

November 24, 2013

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Comet Hale-Bopp, the Great Comet of 1997, was quite a sight. In the above photograph taken on 1997 April 6, Comet Hale-Bopp was imaged from the Indian Cove Campground in the Joshua Tree National Park in California, USA. A flashlight was used to momentarily illuminate foreground rocks in this six minute exposure. An impressive blue ion tail was visible above a sunlight-reflecting white dust tail. Comet Hale-Bopp remained visible to the unaided eye for over a year before returning to the outer Solar System and fading. As Comet ISON approaches the Sun this week, sky enthusiasts around the Earth are waiting to see if its tails will become even more spectacular than those displayed by Comet Hale-Bopp.

November 23, 2013

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Comets grow bright when they're close to the Sun, basking in the intense solar radiation. Of course, they're also usually impossible to see against the overwhelming scattered sunlight. But surprising Comet McNaught - whose January 12 closest approach to the Sun (perihelion passage) in 2007 was well inside the orbit of Mercury - gave an enjoyable performance in bright blue daytime skies. In fact, comet expert David Levy captured this remarkable inset (upper left) telescopic view of McNaught within an hour of perihelion, with the comet in broad daylight only about 7 degrees away from the Sun's position. Stefan Seip's wider daytime view of the comet and fluffy clouds was recorded approximately a day later. Seip used a polarizing filter and a telescope/camera set up near Stuttgart, Germany. No longer visible in broad daylight, Comet McNaught is now touring twilight southern skies.

November 22, 2013

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An astronomical trip from the California Nebula to the Pleiades star cluster would cover just over 12 degrees across planet Earth's night sky. That's equivalent to the angular extent of 25 Full Moons, as your telescope sweeps past the borders of the constellations Perseus and Taurus. This wide and deep mosaic image of the region explores the cosmic landscape's dusty nebulae and colors otherwise too faint for your eye to see. On the left, cataloged as NGC 1499, the California Nebula does have a familiar shape, though its coastline is actually over 60 light-years long and lies about 1,500 light-years away. The nebula's pronounced reddish glow is from hydrogen atoms ionized by luminous blue star Xi Persei seen just to its right. At the far right, the famous Pleiades star cluster is some 400 light-years distant and around 15 light-years across. Its spectacular blue color is due to the reflection of starlight by interstellar dust. In between are hot stars of the Perseus OB2 association and dusty, dark nebulae along the edge of the nearby, massive Perseus molecular cloud.

November 21, 2013

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Star trails arc above a moonlit beach and jetty in this serene sea and night skyscape. Captured on November 19, the single time exposure looks south down the Atlantic coast from Cape Cod, Massachusetts, USA. But the longest and brightest trail is a Minotaur 1 rocket, a stage separation and exhaust plume visible along the rocket's fiery path toward low Earth orbit. The multi-stage Minotaur was launched from the Mid-Atlantic Regional Spaceport at NASA's Wallops Flight Facility at 8:15 p.m Eastern Time in Virginia, about 400 miles away. On board were a remarkable 29 satellites destined for low Earth orbit, including a small cubesat built by high school students, and Firefly, a satellite that will study lightning to see if they generate gamma ray bursts.

November 20, 2013

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What are black hole jets made of? Many black holes in stellar systems are surely surrounded by disks of gas and plasma gravitationally pulled from a close binary star companion. Some of this material, after approaching the black hole, ends up being expelled from the star system in powerful jets emanating from the poles of the spinning black hole. Recent evidence indicates that these jets are composed not only electrons and protons, but also the nuclei of heavy elements such as iron and nickel. The discovery was made in system 4U1630-47 using CSIRO’s Compact Array of radio telescopes in eastern Australia, and the European Space Agency's Earth-orbiting XMM-Newton satellite. The 4U1630-47 star system is depicted above in an artist's illustration, with a large blue star on the right and jets emanating from a black hole in the center of the accretion disc on the left. Although the 4U1630-47 star system is thought to contain only a small black hole - a few times the mass of our Sun - the implications of the results may be larger: that black holes of larger sizes might also be emitting jets of massive nuclei into the cosmos.

November 19, 2013

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Stars, like bees, swarm around the center of bright globular cluster M15. This ball of over 100,000 stars is a relic from the early years of our Galaxy, and continues to orbit the Milky Way's center. M15, one of about 170 globular clusters remaining, is noted for being easily visible with only binoculars, having at its center one of the densest concentrations of stars known, and containing a high abundance of variable stars and pulsars. Released only recently, this sharp image taken by the Earth-orbiting Hubble Space Telescope spans about 120 light years. It shows the dramatic increase in density of stars toward the cluster's center. M15 lies about 35,000 light years away toward the constellation of the Winged Horse (Pegasus).

November 18, 2013

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What's happening in the sky? On this cold winter night in Iceland, quite a lot. First, in the foreground, lies the largest glacier in Iceland: Vatnajokull. On the far left, bright green auroras appear to emanate from the glacier as if it was a volcano. Aurora light is reflected by the foreground lake Jökulsárlón. On the far right is a long and unusual lenticular cloud tinged with green light emitted from another aurora well behind it. Just above this lenticular cloud are unusual iridescent lenticular clouds displaying a broad spectral range of colors. Far beyond the lenticular is the setting Moon, while far beyond even the Moon are setting stars. The above image was captured in late March of 2012.

November 17, 2013

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Comet McNaught, the Great Comet of 2007, grew a spectacularly long and filamentary tail. The magnificent tail spread across the sky and was visible for several days to Southern Hemisphere observers just after sunset. The amazing tail showed its greatest extent on long-duration, wide-angle camera exposures. During some times, just the tail itself estimated to attain a peak brightness of magnitude -5 (minus five), was caught by the comet's discoverer in the above image just after sunset in January 2007 from Siding Spring Observatory in Australia. Comet McNaught, the brightest comet in decades, then faded as it moved further into southern skies and away from the Sun and Earth. Within the next two weeks of 2013, rapidly brightening Comet ISON might sprout a tail that rivals even Comet McNaught.

November 16, 2013

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Falling through planet Earth's predawn skies toward its close encounter with the Sun on November 28, Comet ISON is coming to life. The much anticipated comet has now been reported to have substantially increased in brightness, surging to naked-eye visibility for dark sites and sprouting a more complex tail. ISON's tail stretches over two degrees in this telephoto skyview from southern Kenya, captured on the morning of November 15. Shown in two panels, the enlarged negative version on the right makes details of the long tail easier to trace, including the tail's separated filaments toward the top of the frame. A sungrazer and first time visitor to the inner solar system, the possibility of ISON's survival to become a bright comet in planet Earth's December skies remains a question.

November 15, 2013

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In a flash, the visible spectrum of the Sun changed from absorption to emission on November 3rd, during the brief total phase of a solar eclipse. That fleeting moment is captured by telephoto lens and diffraction grating in this well-timed image from clearing skies over Gabon in equatorial Africa. With overwhelming light from the Sun's disk blocked by the Moon, the normally dominant absorption spectrum of the solar photosphere is hidden. What remains, spread by the diffraction grating into the spectrum of colors to the right of the eclipsed Sun, are individual eclipse images at each wavelength of light emitted by atoms along the thin arc of the solar chromosphere. The brightest images, or strongest chromospheric emission lines, are due to Hydrogen atoms that produce the red hydrogen alpha emission at the far right and blue hydrogen beta emission to the left. In between, the bright yellow emission image is caused by atoms of Helium, an element only first discovered in the flash spectrum of the Sun.

November 14, 2013

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Enigmatic spiral galaxy NGC 1097 shines in southern skies, about 45 million light-years away in the chemical constellation Fornax. Its blue spiral arms are mottled with pinkish star forming regions in this colorful galaxy portrait. They seem to have wrapped around a small companion galaxy below and left of center, about 40,000 light-years from the spiral's luminous core. That's not NGC 1097's most peculiar feature, though. The very deep exposure hints of faint, mysterious jets, most easily seen to extend well beyond the bluish arms toward the lower right. In fact, four faint jets are ultimately recognized in optical images of NGC 1097. The jets trace an X centered on the galaxy's nucleus, but probably don't originate there. Instead, they could be fossil star streams, trails left over from the capture and disruption of a much smaller galaxy in the large spiral's ancient past. A Seyfert galaxy, NGC 1097's nucleus also harbors a supermassive black hole.

November 13, 2013

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In the shadow of Saturn, unexpected wonders appear. The robotic Cassini spacecraft now orbiting Saturn drifted in giant planet's shadow earlier this year and looked back toward the eclipsed Sun. Cassini saw a unique and celebrated view. First, the night side of Saturn is seen to be partly lit by light reflected from its own majestic ring system. Next, Saturn's expansive ring system appears as majestic as always even from this odd angle. Ring particles, many glowing only as irregular crescents, slightly scatter sunlight toward Cassini in this natural color image. Several moons and ring features are also discernible. Appearing quite prominently is Saturn's E ring, the ring created by the unusual ice-fountains of the moon Enceladus and the outermost ring visible above. To the upper left, far in the distance, are the planets Mars and Venus. To the lower right, however, is perhaps the most wondrous spectacle of all: the almost invisible, nearly ignorable, pale blue dot of Earth. For the full resolution image, click here: http://apod.nasa.gov/apod/image/1311...tated_9000.jpg

November 12, 2013

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Found among the rich starfields of the Milky Way toward the constellation Cassiopeia, star cluster NGC 7789 lies about 8,000 light-years away. A late 18th century deep sky discovery of astronomer Caroline Lucretia Herschel, the cluster is also known as Caroline's Rose. Its suggestive appearance is created by the cluster's nestled complex of stars and voids. Now estimated to be 1.6 billion years young, the galactic or open cluster of stars also shows its age. All the stars in the cluster were likely born at the same time, but the brighter and more massive ones have more rapidly exhausted the hydrogen fuel in their cores. These have evolved from main sequence stars like the Sun into the many red giant stars shown with a yellowish cast in this lovely color composite. Using measured color and brightness, astronomers can model the mass and hence the age of the cluster stars just starting to "turn off" the main sequence and become red giants. Over 50 light-years across, Caroline's Rose spans about half a degree (the angular size of the moon) near the center of the wide-field telescopic image.

November 11, 2013

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Sometimes, a total eclipse of the Sun is an opportunity. Taking advantage of such, the above image shows the solar eclipse earlier this month as covered and uncovered by several different solar observatories. The innermost image shows the Sun in ultraviolet light as recorded over a few hours by the SWAP instrument aboard the PROBA2 mission in a sun-synchronous low Earth orbit. This image is surrounded by a ground-based eclipse image, reproduced in blue, taken from Gabon. Further out is a circularly blocked region used to artificially dim the central sun by the LASCO instrument aboard the Sun-orbiting SOHO spacecraft. The outermost image - showing the outflowing solar corona - was taken by LASCO ten minutes after the eclipse and shows an outflowing solar corona. Over the past few weeks, our Sun has been showing an unusually high amount of sunspots, CMEs, and flares - activity that was generally expected as the Sun is currently going through Solar Maximum - the busiest part of its 11 year solar cycle. The above resultant image is a picturesque montage of many solar layers at once that allows solar astronomers to better match up active areas on or near the Sun's surface with outflowing jets in the Sun's corona.

November 10, 2013

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Sometimes the sky itself is the best show in town. In January 2007, people from Perth, Australia gathered on a local beach to watch a sky light up with delights near and far. Nearby, fireworks exploded as part of Australia Day celebrations. On the far right, lightning from a thunderstorm flashed in the distance. Near the image center, though, seen through clouds, was the most unusual sight of all: Comet McNaught. The photogenic comet was so bright that it even remained visible though the din of Earthly flashes. Comet McNaught has now returned to the outer Solar System and is now only visible with a large telescope. The above image is actually a three photograph panorama digitally processed to reduce red reflections from the exploding firework.

November 9, 2013

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While anxiously waiting for Comet ISON to brighten further as it falls toward the Sun, northern skygazers can also find three other bright comets in the east before dawn. In fact, Comet Lovejoy C/2013 R1 is currently the morning sky's brightest. Only discovered in September and not a sungrazing comet, this Comet Lovejoy is nearing the edge of naked-eye visibility and might be spotted from very dark sky sites. Sporting a greenish coma and tail in this telescopic view taken on November 7, Comet Lovejoy is about 0.5 AU from our fair planet and 1.2 AU from the Sun. The comet is having a photogenic Messier moment, sweeping past well known star cluster M44, the Beehive in Cancer. Yellowish bright star Delta Cancri is near the bottom of the frame.

November 8, 2013

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The Sun's disk was totally eclipsed for a brief 20 seconds as the Moon's dark umbral shadow raced across Pokwero in northwestern Uganda on November 3rd. So this sharp telescopic view of totality in clear skies from the central African locale was much sought after by eclipse watchers. In the inspiring celestial scene the Moon just covers the overwhelmingly bright photosphere, the lower, normally visible layer of the Sun's atmosphere. Extending beyond the photosphere, the reddish hydrogen alpha glow of the solar chromosphere outlines the lunar silhouette, fading into the Sun's tenuous, hot, outer atmosphere or corona. Planet-sized prominences reaching beyond the limb of the active Sun adorn the edges of the silhouette, including a cloud of glowing plasma separated from the chromosphere near the 1 o'clock position.

November 7, 2013

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Was there ever another comet like ISON? Although no two comets are exactly alike, one that appears to have had notable similarities was Comet Kirch, the Great Comet of 1680. Like approaching Comet ISON, Comet Kirch was a bright sungrazer, making a very close approach to the surface of the Sun. Neither comet, coincidently, is a member of the most common group of sungrazers - the Kreutz group - populated by remnants of a comet that disintegrated near the Sun hundreds of years ago. The long tail of Comet Kirch is depicted in the above painting by Lieve Versheier. As pictured, some members of the foreground crowd of Rotterdam in the Netherlands are holding cross-staffs, an angle measuring device that predated the sextant. No one knows how Comet ISON will develop, but like Comet Kirch, it is expected to be brightest when very near the Sun, in ISON's case during last few days of November.

November 6, 2013

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It is still not known why the Sun's light is missing some colors. Here are all the visible colors of the Sun, produced by passing the Sun's light through a prism-like device. The spectrum was created at the McMath-Pierce Solar Observatory and shows, first off, that although our white-appearing Sun emits light of nearly every color, it does indeed appear brightest in yellow-green light. The dark patches in the above spectrum arise from gas at or above the Sun's surface absorbing sunlight emitted below. Since different types of gas absorb different colors of light, it is possible to determine what gasses compose the Sun. Helium, for example, was first discovered in 1870 on a solar spectrum and only later found here on Earth. Today, the majority of spectral absorption lines have been identified - but not all.

November 5, 2013

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Even though Kepler-78b is only slightly larger than the Earth, it should not exist. Its size is extraordinary only in the sense that it is the most similar in size to the Earth of any exoplanet yet directly discovered. Its orbit, however, is extraordinary in the sense that it circles a Sun-like star 40 times closer than planet Mercury. At such a scathing distance, even rock is liquid. Models of planet formation predict that no planet can form in such a close orbit, and models of planet evolution predict that Kepler-78b's orbit should decay -- dooming the planet to eventually merge with its parent star. Illustrated above in comparison with the Earth, Kepler-78b was discovered by eclipse with the Earth-orbiting Kepler spacecraft and further monitored for subtle wobbles by the HARPS- North, a spectrograph attached to the 3.6-meter Telescopio Nazionale Galileo in the Canary Islands.

November 4, 2013

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A sunrise over New York City rarely looks like this. Yesterday, however, the Sun rose partly eclipsed by the Moon as seen from much of the eastern North American and northern South America. Simultaneously, much of Africa, already well into daytime, saw the eclipse from beginning to end. The eclipse was unusual in that it was a hybrid - parts of the Earth saw the Moon as too angularly small to cover the whole Sun, and so at maximum coverage left the Sun surrounded by a ring a fire, while other parts of the Earth saw the Moon as large enough to cover the entire Sun, and so at maximum coverage witnessed a total solar eclipse. Slight changes in the angular size of the Moon as seen from the Earth's surface are caused by the non-flatness of the Earth and the ellipticity of the Moon's orbit. Pictured above, the famous Empire State Building in New York City is seen to the left of the partially eclipsed Sun, adorned with scenic clouds. The next solar eclipse visible from New York City - a very slight eclipse - will occur during the sunset of 2014 October 23.

November 3, 2013

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A spectacular geocentric celestial event of 2005 was a rare hybrid eclipse of the Sun - a total or an annular eclipse could be seen depending on the observer's location. For Fred Espenak, aboard a gently swaying ship within the middle of the Moon's shadow track about 2,200 kilometers west of the Galapagos, the eclipse was total, the lunar silhouette exactly covering the bright solar disk for a few brief moments. His camera captured a picture of totality revealing the extensive solar corona and prominences rising above the Sun's edge. But for Stephan Heinsius, near the end of the shadow track at Penonome Airfield, Panama, the Moon's apparent size had shrunk enough to create an annular eclipse, showing a complete annulus of the Sun's bright disk as a dramatic ring of fire. Pictures from the two locations are compared above. How rare is such a hybrid eclipse? Calculations show that during the 21st century just 3.1% (7 out of 224) of solar eclipses are hybrid while hybrids comprise about 5% of all solar eclipses over the period 2000 BC to AD 3000. Today's hybrid solar eclipse is most widely visible beyond the central shadow track as a brief partial eclipse from northeastern Americas through Africa, and along the track in an annular phase for only the first 15 seconds.

My own photos of the eclipse as seen from the shores of Toronto are below. Departing at 5am, passing through over half the city, and battling wind chills of -9 for a couple hours to find the best position resulted in the following photographs.





November 2, 2013

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What spooky planet is this? Planet Earth of course, on the dark and stormy night of September 12 at Hverir, a geothermally active area along the volcanic landscape in northeastern Iceland. Geomagnetic storms produced the auroral display in the starry night sky while ghostly towers of steam and gas venting from fumaroles danced against the eerie greenish light. Tonight, there is still a chance for geomagnetic storms triggered by recent solar activity, so high-latitude skygazers should beware.

November 1, 2013

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Frightening forms and scary faces are a mark of the Halloween season. They also haunt this cosmic close-up of the eastern Veil Nebula. The Veil Nebula itself is a large supernova remnant, the expanding debris cloud from the death explosion of a massive star. While the Veil is roughly circular in shape covering nearly 3 degrees on the sky in the constellation Cygnus, this portion of the eastern Veil spans only 1/2 degree, about the apparent size of the Moon. That translates to 12 light-years at the Veil's reassuring estimated distance of 1,400 light-years from planet Earth. In the composite of image data recorded through narrow band filters, emission from hydrogen atoms in the remnant is shown in red with strong emission from oxygen atoms in blue-green hues. In the western part of the Veil lies another seasonal apparition, the Witch's Broom.

October 31, 2013

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The dark Horsehead Nebula and the glowing Orion Nebula are contrasting cosmic vistas. Adrift 1,500 light-years away in one of the night sky's most recognizable constellations, they appear in opposite corners of the above stunning mosaic. The familiar Horsehead nebula appears as a dark cloud, a small silhouette notched against the long red glow at the lower left. Alnitak is the easternmost star in Orion's belt and is seen as the brightest star to the left of the Horsehead. Below Alnitak is the Flame Nebula, with clouds of bright emission and dramatic dark dust lanes. The magnificent emission region, the Orion Nebula (aka M42), lies at the upper right. Immediately to its left is a prominent reflection nebula sometimes called the Running Man. Pervasive tendrils of glowing hydrogen gas are easily traced throughout the region.

October 30, 2013

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Arcing toward a fiery fate, this Sungrazer comet was recorded by the SOHO spacecraft's Large Angle Spectrometric COronagraph(LASCO) on December 23, 1996. LASCO uses an occulting disk, partially visible at the lower right, to block out the otherwise overwhelming solar disk allowing it to image the inner 8 million kilometers of the relatively faint corona. The comet is seen as its coma enters the bright equatorial solar wind region (oriented vertically). Positioned in space to continuously observe the Sun, SOHO has now been used to discover over 1,500 comets, including numerous sungrazers. Based on their orbits, the vast majority of sungrazers are believed to belong to the Kreutz family of sungrazing comets created by successive break ups from a single large parent comet that passed very near the Sun in the twelfth century. The Great Comet of 1965, Ikeya-Seki, was also a member of the Kreutz family, coming within about 650,000 kilometers of the Sun's surface. Passing so close to the Sun, Sungrazers are subjected to destructive tidal forces along with intense solar heat. This small comet, known as the Christmas Comet SOHO 6, did not survive. Later this year, Comet ISON, potentially the brightest sungrazer in recorded history but not a Kreutz sungrazer, is expected to survive.

October 29, 2013

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If you climbed this magnificent tree, it looks like you could reach out and touch the North Celestial Pole at the center of all the star trail arcs. The well-composed image was recorded over a period of nearly 2 hours as a series of 30 second long, consecutive exposures on the night of October 5. The exposures were made with a digital camera fixed to a tripod near Almaden de la Plata, province of Seville, in southern Spain, planet Earth. Of course, the graceful star trails reflect the Earth's daily rotation around its axis. By extension, the axis of rotation leads to the center of the concentric arcs in the night sky. Convenient for northern hemisphere night sky photographers and celestial navigators alike, the bright star Polaris is very close to the North Celestial Pole and so makes the short bright trail in the central gap between the leafy branches.

October 28, 2013

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For reasons unknown, NGC 6357 is forming some of the most massive stars ever discovered. One such massive star, near the center of NGC 6357, is framed above carving out its own interstellar castle with its energetic light from surrounding gas and dust. In the greater nebula, the intricate patterns are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity. The overall glow of the nebula results from the emission of light from ionized hydrogen gas. Near the more obvious Cat's Paw nebula, NGC 6357 houses the open star cluster Pismis 24, home to many of these tremendously bright and blue stars. The central part of NGC 6357 shown spans about 10 light years and lies about 8,000 light years away toward the constellation of the Scorpion.

October 27, 2013

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This image of Saturn could not have been taken from Earth. No Earth based picture could possibly view the night side of Saturn and the corresponding shadow cast across Saturn's rings. Since Earth is much closer to the Sun than Saturn, only the day side of the ringed planet is visible from the Earth. In fact, this image mosaic was taken earlier this month by the robotic Cassini spacecraft now orbiting Saturn. The beautiful rings of Saturn are seen in full expanse, while cloud details are visible including the polar hexagon surrounding the north pole, and an extended light-colored storm system.

October 26, 2013

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Diffuse starlight and dark nebulae along the southern Milky Way arc over the horizon and sprawl diagonally through this gorgeous nightscape. The breath-taking mosaic spans a wide 100 degrees, with the rugged terrain of the Patagonia, Argentina region in the foreground. Along with the insider's view of our own galaxy, the image features our outside perspective on two irregular satellite galaxies - the Large and Small Magellanic Clouds. The scene also captures the broad tail and bright coma of Comet McNaught, the Great Comet of 2007. Currently, many sky enthusiasts are following the development of Comet ISON, a comet which might become the Great Comet of 2013.

October 25, 2013

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The bulging center of our Milky Way Galaxy rests on a pillar of light in this luminous skyscape. Recorded on September 22nd in dark South African skies, rivers of dust seem to flow downward from the galactic center towards Antares, yellowish alpha star of the constellation Scorpius, near the top of the scene. The brightest celestial beacon present is not a star at all though, but planet Venus, still dominant in the western sky after sunset. Of course, the pillar of light stretching upward from the horizon is Zodiacal light. Sunlight scattered by dust along the plane of the ecliptic creates the zodiacal glow, prominent in the evening after twilight during the southern hemisphere spring.

October 24, 2013

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This intriguing trio of galaxies is sometimes called the Draco Group, located in the northern constellation of (you guessed it) Draco. From left to right are edge-on spiral NGC 5981, elliptical galaxy NGC 5982, and face-on spiral NGC 5985 - all within this single telescopic field of view spanning a little more than half the width of the full moon. While the group is far too small to be a galaxy cluster and has not been catalogued as a compact group, these galaxies all do lie roughly 100 million light-years from planet Earth. On close examination with spectrographs, the bright core of the striking face-on spiral NGC 5985 shows prominent emission in specific wavelengths of light, prompting astronomers to classify it as a Seyfert, a type of active galaxy. Not as well known as other tight groupings of galaxies, the contrast in visual appearance makes this triplet an attractive subject for astrophotographers. This impressively deep exposure hints at faint, sharp-edged shells surrounding elliptical NGC 5982, evidence of past galactic mergers. It also reveals many even more distant background galaxies.

October 23, 2013

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Sixteen years ago, Comet Hale-Bopp rounded the Sun and offered a dazzling spectacle in planet Earth's night. This stunning view, recorded shortly after the comet's 1997 perihelion passage, features the memorable tails of Hale-Bopp - a whitish dust tail and blue ion tail. Here, the ion tail extends well over ten degrees across the northern sky, fading near the double star clusters in Perseus, while the head of the comet lies near Almach, a bright star in the constellation Andromeda. Do you remember Hale-Bopp? The photographer's sons do, pictured in the foreground at ages 12 and 15. In all, Hale-Bopp was reported as visible to the naked eye from roughly late May 1996 through September 1997. Currently, sky enthusiasts await Comet ISON's continued brightening in the coming weeks, unsure how interesting its first journey to the inner Solar System will be.

October 22, 2013

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Bright-rimmed, flowing shapes gather near the center of this rich starfield toward the boarders of the nautical southern constellations Pupis and Vela. Composed of interstellar gas and dust, the grouping of light-year sized cometary globules is about 1300 light-years distant. Energetic ultraviolet light from nearby hot stars has molded the globules and ionized their bright rims. The globules also stream away from the Vela supernova remnant which may have influenced their swept-back shapes. Within them, cores of cold gas and dust are likely collapsing to form low mass stars, whose formation will ultimately cause the globules to disperse. In fact, cometary globule CG30 (upper right in the group) sports a small reddish glow near its head, a telltale sign of energetic jets from a star in the early stages of formation.

October 21, 2013

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This sharp cosmic portrait features NGC 891. The spiral galaxy spans about 100 thousand light-years and is seen almost exactly edge-on from our perspective. In fact, about 30 million light-years distant in the constellation Andromeda, NGC 891 looks a lot like our Milky Way. At first glance, it has a flat, thin, galactic disk and a central bulge cut along the middle by regions of dark obscuring dust. The combined image data also reveal the galaxy's young blue star clusters and telltale pinkish star forming regions. And remarkably apparent in NGC 891's edge-on presentation are filaments of dust that extend hundreds of light-years above and below the center line. The dust has likely been blown out of the disk by supernova explosions or intense star formation activity. Faint neighboring galaxies can also be seen near this galaxy's disk.

October 20, 2013

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To the eye, this cosmic composition nicely balances the Bubble Nebula at the lower left with open star cluster M52 above it and to the right. The pair would be lopsided on other scales, though. Embedded in a complex of interstellar dust and gas and blown by the winds from a single, massive O-type star, the Bubble Nebula, also known as NGC 7635, is a mere 10 light-years wide. On the other hand, M52 is a rich open cluster of around a thousand stars. The cluster is about 25 light-years across. Seen toward the northern boundary of Cassiopeia, distance estimates for the Bubble Nebula and associated cloud complex are around 11,000 light-years, while star cluster M52 lies nearly 5,000 light-years away. The wide telescopic field of view spans about two degrees on the sky or four times the apparent size of the Full Moon.

October 19, 2013

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Active galaxy NGC 1275 is the central, dominant member of the large and relatively nearby Perseus Cluster of Galaxies. Wild-looking at visible wavelengths, the active galaxy is also a prodigious source of x-rays and radio emission. NGC 1275 accretes matter as entire galaxies fall into it, ultimately feeding a supermassive black hole at the galaxy's core. This color composite image, recreated from archival Hubble Space Telescope data, highlights the resulting galactic debris and filaments of glowing gas, some up to 20,000 light-years long. The filaments persist in NGC 1275, even though the turmoil of galactic collisions should destroy them. What keeps the filaments together? Observations indicate that the structures, pushed out from the galaxy's center by the black hole's activity, are held together by magnetic fields. Also known as Perseus A, NGC 1275 spans over 100,000 light years and lies about 230 million light years away.

October 18, 2013

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The bright core and outer reaches of giant elliptical galaxy M60 (NGC 4649) loom large at the upper left of this sharp close-up from the Hubble Space Telescope. Some 54 million light-years away and 120,000 light-years across, M60 is one of the largest galaxies in the nearby Virgo Cluster. In cosmic contrast, the small, round smudge at picture center is now recognized as an ultra-compact dwarf galaxy. Cataloged as M60-UCD1, it may well be the densest galaxy in the nearby universe. Concentrating half of its total mass of 200 million suns into a radius of only 80 light-years, stars in the inner regions of M60-UCD1 are on average 25 times closer together than in planet Earth's neighborhood of the Milky Way. Exploring the nature of M60-UCD1, astronomers are trying to determine if ultra-compact dwarf galaxies are the central remnants of larger galaxies that have been tidally stripped by gravitatonal encounters, or evolved as massive globular star clusters. Recently discovered, a bright X-ray source seen at its center could be due to a supermassive black hole. If so, that would favor a remnant galaxy origin for M60-UCD1. A link to the report that claims this is the densest galaxy is found here.

October 17, 2013

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Close to the Great Bear (Ursa Major) and surrounded by the stars of the Hunting Dogs (Canes Venatici), this celestial wonder was discovered in 1781 by the metric French astronomer Pierre Mechain. Later, it was added to the catalog of his friend and colleague Charles Messier as M106. Modern deep telescopic views reveal it to be an island universe: a spiral galaxy around 30 thousand light-years across located only about 21 million light-years beyond the stars of the Milky Way. Along with prominent dust lanes and a bright central core, this colorful composite image highlights youthful blue star clusters and reddish stellar nurseries that trace the galaxy's spiral arms. The high resolution galaxy portrait is a mosaic of data from Hubble's sharp ACS camera combined with groundbased color image data. M106 (aka NGC 4258) is a nearby example of the Seyfert class of active galaxies, seen across the spectrum from radio to X-rays. Energetic active galaxies are powered by matter falling into a massive central black hole.

October 16, 2013

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This photo is the winner of the Royal Museums Greenwich astronomy photographer of the year: earth and space category. This is a spectacular view of the Milky Way arching over the coast of the North Island of New Zealand. The brightest light in the image is from the Cape Palliser Lighthouse. The central patch of light in the sky marks the bulge of stars at the heart of our Galaxy, 26,000 light years away. To the left, the two Magellanic Clouds, small satellite galaxies much further away, appear as faint smudges in the sky. The following is a quote from the author, Mark Gee:

‘I recently spent a night out at Cape Palliser on the North Island of New Zealand, photographing the night sky. I woke after a few hours’ sleep at 5 a.m. to see the Milky Way low in the sky above the Cape. The only problem was that my camera gear was at the top of the lighthouse, seen to the right of this image, so I had to climb the 250-plus steps to retrieve it before I could take this photo...

‘By the time I got back the sky was beginning to get lighter with sunrise only two hours away. It looked surreal but amazing as the twilight started to creep into the night sky. I took a wide panorama made up of 20 individual images to get this shot. Stitching the images together was a challenge but the result was worth it!’

Canon 5D Mark III camera; 24mm f/2.8 lens; ISO 3200; 30-second exposure

October 15, 2013

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How do you find Comet ISON? Wake up before dawn, face east, and follow the "double star." Rising about three hours before the sun, red Mars and blue-white Regulus have converged to form a bright pair separated by only 1o. Martin Gembec photographed the duo from the Czech Republic before daybreak on Oct. 14th. Comet ISON is just above Mars in this photograph. On Nov. 28th, Comet ISON could become spectacularly bright when it flies through the atmosphere of the sun. At the moment, though, it is still far away (near Mars) and faint. Visibility requires a telescope.

October 14, 2013

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A pair of sunspot groups in the sun's southern hemisphere poses a threat for Earth-directed eruptions. They're photogenic, too. Alex Dzierba took this picture of the sunspots rising over Koko crater in Honolulu, Hawaii, on Oct. 13th. He used a Coronado Personal Solar Telescope with a Ca/K filter. Ca/k or "Calcium K" filters are sensitive to light from ionized calcium in the sun's atmosphere. This kind of light reveals the bright magnetic froth around sunspots - and these sunspots are very frothy indeed. Sunrises in the week ahead could be punctuated by eruptions. NOAA forecasters estimate a 40% chance of M-class flares and a 10% chance of X-flares on Oct. 14th.

October 13, 2013

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The triple transit Jupiter experienced October 12th was seen throughout most of Europe and parts of North America. This movie from Kocaeli, TURKEY was taken by Ahmet Kale between 7:20am - 8:00am. He writes, "It was very cloudy that night, but I waited patiently until the morning to find an opportunity to take this special moment. I was lucky, clouds gone just before the event started and I managed to capture this events first 30 minutes. The Sun was at about 10 degree high, So I just use 742 nm IR filter." Equipment he used consisted of a C11 EdgeHD on CGEM DX telescope, ZWO ASI 120MM camera, Astronomik ProPlanet IR742 Filter, and 34 x 1 minute captures at 150fps.

The key to this capture was the filter. The ProPlanet IR 742 only allows infrared light with wavelengths of more than 742 nm to pass. In this wavelength range the effects of seeing are significantly lower than in the visible spectrum of the human eye. This allows much sharper images than are usually obtained from your device and location. Another advantage is that the sky background of advanced dawn is dark and so the filter even allows photography of the planets and the moon at daylight. This series of photos was taken well after sunrise due to clouds, and would not have been possible without this piece of equipment.

October 12, 2013

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Yesterday, A rare case of three moons — Io, Europa, and Callisto — casting their tiny black shadows onto Jupiter at once happened late last night, from 4:32 to 5:37 Universal Time October 12th (12:32 to 1:37 a.m. Saturday morning Eastern Daylight Time). Jupiter was high and best placed for telescope users in Europe and Africa, and low in the eastern sky for eastern North America. This is the same as having 3 lunar eclipses happening at the same time on the planet. This photo in particular is from Günther Strauch of Borken, Germany.

October 11, 2013

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If you have a solar telescope, depending on where you live, you have access to a day long show in that of the sun. This year is a particularly interesting year in the advent of solar maximum, albeit the weakest solar maximum in 100 years. However, there is speculation that this solar max will be double peaked, where the first peak has already passed us and we're presently in a lull. It's just a matter of time under this theory that the sun picks up again, and early speculation appears to be such that it may be picking right back up again. Here is a look at the AR1864 and AR1865 from 10:54 to 11:54UT by an amateur astronomer. Seeing was generally poor, but equipment used was an SM90 and DMK51 mono camera.

October 10, 2013

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An interplanetary shock wave, possibly the leading edge of a CME, hit Earth's magnetic field on October 8th at approximately 2015 UT. The impact sparked a G1-class geomagnetic storm and bright auroras around the Arctic Circle. Harald Albrigtsen sends this picture from Tromsø, Norway. Solar wind speeds remain elevated (~450 km/s) as Earth exits the wake of the CME. As a result, NOAA forecasters estimate a 40% chance of polar geomagnetic storms on Oct. 10th. The photo itself is a 10 second exposure at ISO 1600 acording to the photgorapher. During geomagnetic storms, the northern lights are easily luminous enough to reflect in still water.

October 9, 2013

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During the night time hours of October 8, a minor Coronal Mass Ejection (CME) impacted the magnetic field of the Earth. The impact sparked a G1-class geomagnetic storm where the northern lights could be seen as far south as Ohio. If you are a northern latitude watcher, you were given the best show however. This photo, by B.Art Braafhart of Salla, Finnish-Lapland, had front row seats to a particular intense section of the storm that pierced not only through an otherwise overcast night, but also illuminated the lake in eerie tones of green. Braafhart estimates that the storm he witnessed peaked at a Kp index of 6.33 as opposed to 5. The overcast sky contributes significantly to the eerie effect of this image. Tonight, there is a 65% chance that strong geomagnetic activity continues.

October 8, 2013

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Earth is not the only planet in the solar system to be struck by the sun's radiation. Planets as far as Saturn have been known to form auroras. This sequence of three images taken by Hubble Space telescope of Saturn was taken over two day intervals. The auroras are caused by charged particles entering the atmosphere of Saturn, much like how it happens on Earth. Auroras have also been discovered on Jupiter.

October 7, 2013

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The light spectra of the zodiacal light is the same as that of the sun. A part of the light absorbed by dust is re-emittted as infrared radiation. The zodiacal light is visible to the right of this picture, as a bright, triangular shaped entity. This photo was taken just after sunset in Nambia, June 2009 in the Southern Hemisphere. While the zodiacal light is often only found in the darkest of skies, it is often referred to as the "false dawn" due to its vast luminous expanse. The zodiacal light is the brightest typically around the time of the autumnal and vernal equinoxes. Credit & Copyright: Rudi Dobesberger (Sternfreunde Steyr).

October 6, 2013

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The Gegenschein is an elliptical glow in the night sky in the antisolar point. Not to be confused with the Zodiacal Light which is a reflection of sunlight from dust directly reflecting Earth, the Gegenschein is a much fainter reflection of light reflecting back from the Zodiacal Light towards Earth. The image was captured by Yuri Beletsky in October 2007 using a digital camera with a wide-angle 10 mm and installed on a portable equatorial mount lens. The sky in this picture is about as good as it gets in regards to transparency, which helped captured the fine structure of the Gegenschein. The image was taken at the Cerro Paranal Observatory, located in the Atacama Desert in northern Chile, at an altitude of 2635 m.

October 5, 2013

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Is it possible to image the International Space Station and transport ships that supply fuel to it from Earth? The answer is yes! The below is a passage from Philip Smith who took this image in Manorville, New York.

I imaged the ISS and Cygnus spacecraft at max 85 deg.on 9-29-13 Time 6:16am EST
I used my Meade 10 with a 2X barlow and an Orange Filter and Skynyx 2.0 M chip size 640x480 on CCD @ 66 FPS
With Emmanuel Rietsch Tracking System
Capture start time = Sunday, 29 September 2013 06:13:50 / UTC -4 Hours
Capture duration = 222.45 Sec

Captured frames = 14676

Capture frame speed = 66 Fps

Camera = Lumenera SKYnyx2-0M
pixel size = 7.40 x 7.40 µm²

Image format = MONO - 12 Bit
Capture format = Tif
Image type = Light frame
RoI size = 640x480
Frame rate = 66.6 Fps
Exposure = 1.01 ms
Gain = 12.8
Gamma = 1.00
Contrast = 1.00
Brightness = 1.0

Two private American companies are now responsible for hauling cargo to the International Space Station.
Orbital Sciences Cygnus spacecraft attached to the orbiting laboratory today by 7:01 a.m. EST a first for the cargo ship. The rendezvous was nearly flawless, according to officials with NASA and the private company.
You can also see my video.

http://www.youtube.com/watch?v=4oyMZkbtMVk

BR
Philip Smith

October 4, 2013

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On October 2nd, a CME hit Earth's magnetic field, sparking a G2-class geomagnetic storm. Sky watchers on both ends of the Earth saw auroras; many of the lights were rare shades of red. Minoru Yoneto photographed this example from Queenstown, New Zealand. "This is how the sky looked 11 hours after the CME impact," says Yoneto, who used a Canon EOS 6D digital camera to record the reds. Auroras are usually green, and sometimes purple, but seldom do sky watchers see this much red. Red auroras occur some 300 to 500 km above Earth's surface and are not yet fully understood. Some researchers believe the red lights are linked to a large influx of electrons. When low-energy electrons recombine with oxygen ions in the upper atmosphere, red photons are emitted. At present, space weather forecasters cannot predict when this will occur. During the storm, even more red auroras were observed over the United States in places like Kansas, Ohio, and Oklahoma.

October 3, 2013

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You don't have to live in a high latitude to experience a great show from the auroras, but it sure helps. The CME that hit Earth's magnetic field today left the sun on Sept. 30th, propelled by an erupting magnetic filament. The CME was impressive, but the underlying explosion was even more so. One movie from NASA's Solar Dynamics Observatory shows the self-destructing filament in the context of the whole sun. This movie is shown below. The above photo was taken by Monika Petersen on October 2, 2013 at Williams Lake, BC, Canada. With a G2 class magnetic storm, the northern lights would have been visible not only to the north, but also to the east, west, and directly above that location.


October 2, 2013

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Lake Tekapo on South Island in New Zealand is arguably one of best night sky locations in the Southern Hemisphere. The significance of its pristine night sky without light pollution is recognised world-wide and is being designateds as an International Dark Sky Reserve as part of a UNESCO-supported initiative to preserve the quality of the night sky and its cultural, scientific, or natural values. This photo was taken by Alex Cherney, a hobbyist astronomer who nicely frames earthly clouds below with celestial clouds above.

October 1, 2013

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The explosion is over but the consequences continue. About eleven thousand years ago a star in the constellation of Vela could be seen to explode, creating a strange point of light briefly visible to humans living near the beginning of recorded history. The outer layers of the star crashed into the interstellar medium, driving a shock wave that is still visible today. A roughly spherical, expanding shock wave is visible in X-rays. The above image captures some of that filamentary and gigantic shock in visible light. As gas flies away from the detonated star, it decays and reacts with the interstellar medium, producing light in many different colors and energy bands. Remaining at the center of the Vela Supernova Remnant is a pulsar, a star as dense as nuclear matter that rotates completely around more than ten times in a single second.

September 30, 2013

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What is it? Some surely natural phenomenon has appeared in a video that, so far, has defied clear identification. The above time-lapse video was made to record Perseid meteors above Hopewell Rocks in New Brunswick, Canada late this summer. The video, which ran from 9:30 pm August 11 to 3:00 am the next morning, records several meteor and satellite streaks beyond a picturesque background. Each image records a 30 second exposure. At about 25 seconds into the video, however, an unusual patchy green glow appears to cover the sky. Possible explanations include airglow, aurora, lighting from an artificial or natural source, or something completely different.

September 29, 2013

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The dust sculptures of the Eagle Nebula are evaporating. As powerful starlight whittles away these cool cosmic mountains, the statuesque pillars that remain might be imagined as mythical beasts. Pictured above is one of several striking dust pillars of the Eagle Nebula that might be described as a gigantic alien fairy. This fairy, however, is ten light years tall and spews radiation much hotter than common fire. The greater Eagle Nebula, M16, is actually a giant evaporating shell of gas and dust inside of which is a growing cavity filled with a spectacular stellar nursery currently forming an open cluster of stars. The above image in scientifically re-assigned colors was released in 2005 as part of the fifteenth anniversary celebration of the launch of the Hubble Space Telescope.

September 28, 2013

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From a geostationary orbit 36,000 kilometers above the equator, Russian meteorological satellite Elektro-L takes high-resolution images our fair planet every 30 minutes. But only twice a year, during an Equinox, can it capture an image like this one, showing an entire hemisphere bathed in sunlight. At an Equinox, the Earth's axis of rotation is not tilted toward or away from the Sun, so the solar illumination can extend to both the planet's poles. Of course, this Elektro-L picture was recorded on September 22nd, at the northern hemisphere's autumnal equinox. For a moment on that date, the Sun was behind the geostationary satellite and a telltale glint of reflected sunlight is seen crossing the equator, at the location on the planet with satellite and sun directly overhead. This gif is shown below.

September 27, 2013

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How far can you see? The Andromeda Galaxy 2.5 million light years away is the most distant object easily seen by the unaided eye. Other apparent denizens of the night sky, stars, clusters, and nebulae, typically range from a few hundred to a few thousand light-years away and lie well within our own Milky Way Galaxy. Also known as M31, the Andromeda Galaxy is the faint smudge near top center of this Earth and skyscape, taken from eastern Italy, near Monte Conero on the Adriatic sea coast. From a few centimeters to a few million light-years, the picture demonstrates a stunning range of vision. Though galaxy and seaside rocks could be seen with the eye on that clear summer night, no camera captured this view in a single exposure. Because the stars trailed above the horizon while the picture was made, separate exposures tracking the stars were combined with one of rocks and cliffs made with the camera steadied to create the tantalizing scene.

September 26, 2013

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Separated by about 14 degrees (28 Full Moons) in planet Earth's sky, spiral galaxies M31 ,left, and M33 are both large members of the Local Group, along with our own Milky Way galaxy. This wide-angle, telescopic mosaic captures colorful details of spiral structure in both, while the massive neighboring galaxies seem to be balanced either side of bright Mirach, beta star in the constellation Andromeda. But M31, the Andromeda Galaxy, is really 2.5 million light-years distant and M33, the Triangulum Galaxy, is also about 3 million light years away. Mirach, just 200 light-years from the Sun, lies well within the Milky Way, along with the dim clouds of dust drifting through the frame only a few hundred light-years above the galactic plane. Although they look far apart, M31 and M33 are locked in a mutual gravitational embrace. Radio astronomers have found indications of a bridge of neutral hydrogen gas that could connect the two, evidence of a closer encounter in the past. Based on measurements, gravitational simulations currently predict that the Milky Way, M31, and M33 will all undergo mutual close encounters and potentially mergers, billions of years in the future.

September 25, 2013

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Here in the Milky Way galaxy we have astronomical front row seats as M81 and M82 face-off, a mere 12 million light-years away. Locked in a gravitational struggle for the past billion years or so, the two bright galaxies are captured in this deep telescopic snapshot, constructed from 25 hours of image data. Their most recent close encounter likely resulted in the enhanced spiral arms of M81 (left) and violent star forming regions in M82 so energetic the galaxy glows in X-rays. After repeated passes, in a few billion years only one galaxy will remain. From our perspective, this cosmic moment is seen through a foreground veil of the Milky Way's stars and clouds of dust. Faintly reflecting the foreground starlight, the pervasive dust clouds are relatively unexplored galactic cirrus, or integrated flux nebulae, only a few hundred light-years above the plane of the Milky Way.

September 24, 2013

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The stars are not alone. In the disk of our Milky Way Galaxy about 10 percent of visible matter is in the form of gas, called the interstellar medium (ISM). The ISM is not uniform, and shows patchiness even near our Sun. It can be quite difficult to detect the local ISM because it is so tenuous and emits so little light. This mostly hydrogen gas, however, absorbs some very specific colors that can be detected in the light of the nearest stars. A working map of the local ISM within 20 light-years, based on ongoing observations and recent particle detections from the Earth-orbiting Interstellar Boundary Exporer satellite (IBEX), is shown above. These observations indicate that our Sun is moving through a Local Interstellar Cloud as this cloud flows outwards from the Scorpius-Centaurus Association star forming region. Our Sun may exit the Local Cloud, also called the Local Fluff, during the next 10,000 years. Much remains unknown about the local ISM, including details of its distribution, its origin, and how it affects the Sun and the Earth. Unexpectedly, recent IBEX spacecraft measurements indicate that the direction from which neutral interstellar particles flow through our Solar System is changing.

September 23, 2013

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South of Antares, in the tail of the nebula-rich constellation Scorpius, lies emission nebula IC 4628. Nearby hot, massive stars, millions of years young, radiate the nebula with invisible ultraviolet light, stripping electrons from atoms. The electrons eventually recombine with the atoms to produce the visible nebular glow, dominated by the red emission of hydrogen. At an estimated distance of 6,000 light-years, the region shown is about 250 light-years across, spanning an area equivalent to four full moons on the sky. The nebula is also cataloged as Gum 56 for Australian astronomer Colin Stanley Gum, but seafood-loving astronomers might know this cosmic cloud as The Prawn Nebula.

September 22, 2013

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Today, the Sun crosses the celestial equator heading south at 20:44 Universal Time. An equinox (equal night), this astronomical event marks the first day of autumn in the northern hemisphere and spring in the south. With the Sun on the celestial equator, Earth dwellers will experience nearly 12 hours of daylight and 12 hours of darkness. To celebrate, consider this remarkable record of the Sun's yearly journey through planet Earth's sky, made with planned multiple exposures captured on a single piece of 35 millimeter film. Exposures were made at the same time of day (9:00am local time), capturing the Sun's position on dates from January 7 through December 20, 2003. The multiple suns trace an intersecting curve known as an analemma. A foreground base exposure of the Temple of Apollo in ancient Corinth, Greece, appropriate for an analemma, was digitally merged with the film image. Equinox dates correspond to the middle points (not the intersection point) of the analemma. The curve is oriented at the corresponding direction and altitude for the temple, so the Sun's position for the September equinox is at the upper midpoint near picture center. Summer and winter solstices are at analemma top and bottom.

September 21, 2013

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The sky looks dark in this scene from the Mid-Atlantic Regional Spaceport (MARS) at NASA Wallops Flight Facility, Virginia. Captured on Wednesday, September 18, an Orbital Sciences Corporation Antares rocket is leaving launch pad-0A with the Cygnus cargo spacecraft aboard. Though it looks like night, the photograph was taken at 10:58am EDT, under bright, clear morning skies, with a digital camera modified to record infrared images. The Sun itself is above and left of the picture frame, creating strong glare and internal reflections in the camera lens at near-infrared wavelengths. In the false-color presentation, the vegetation and watery reflections also take on an otherworldly pallor. Reaching orbit, the Cygnus spacecraft is now on its way to a Sunday rendezvous with the International Space Station. The spacecraft will deliver about 1,300 pounds (589 kilograms) of cargo to the Expedition 37 crew.

September 20, 2013

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Colorful stars trail through this late summer, night skyscape from Cape Cod, Massachusetts. The picture was composed by stacking 12 consecutive 1 minute long digital camera exposures to follow the trails, a reflection of our fair planet's daily rotation. It also records faint clouds of the Milky Way in the clear sky, stretching above a local drive-in movie theater. In fact, watching movies from cars at the drive-in was once a more common night time activity. But while the stars still shine, drive-in theaters have faded from the American landscape over the decades since the 1950s. Still, this recent scene includes a short exposure made as the projector beamed a space age image to the movie screen, and drive-in skygazers watched a view of the Earth below the International Space Station, under the stars above.

September 19, 2013

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In this engaging scene from planet Earth, the Moon shines through cloudy skies following sunset on the evening of September 8. Despite the fading light, the camera's long exposure still recorded a colorful, detailed view of a shoreline and western horizon looking toward the island San Gabriel from Colonia del Sacramento, Uruguay. Lights from Buenos Aires, Argentina are along the horizon on the left, across the broad Rio de la Plata estuary. The long exposure strongly overexposed the Moon and sky around it, though. So the photographer quickly snapped a shorter one to merge with the first image in the area around the bright lunar disk. As the the second image was made with a telephoto setting, the digital merger captures both Earth and sky, exaggerating the young Moon's slender crescent shape in relation to the two nearby bright stars. The more distant is bluish Spica, alpha star of the constellation Virgo. Closest to the Moon is Earth's evening star, planet Venus, emerging from a lunar occultation.

September 18, 2013

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Have you ever seen the Pleiades star cluster? Even if you have, you probably have never seen it as dusty as this. Perhaps the most famous star cluster on the sky, the bright stars of the Pleiades can be seen without binoculars from even the depths of a light-polluted city. With a long exposure from a dark location, though, the dust cloud surrounding the Pleiades star cluster becomes very evident. The above exposure took about 30 hours and covers a sky area several times the size of the full moon. Also known as the Seven Sisters and M45, the Pleiades lies about 400 light years away toward the constellation of the Bull (Taurus). A common legend with a modern twist is that one of the brighter stars faded since the cluster was named, leaving only six stars visible to the unaided eye. The actual number of Pleiades stars visible, however, may be more or less than seven, depending on the darkness of the surrounding sky and the clarity of the observer's eyesight.

September 17, 2013

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It is one of the most massive objects in the visible universe. In this view from the Hubble Space Telescope's Advanced Camera for Surveys, Abell 1689 is seen to warp space as predicted by Einstein's theory of gravity - deflecting light from individual galaxies which lie behind the cluster to produce multiple, curved images. The power of this enormous gravitational lens depends on its mass, but the visible matter, in the form of the cluster's yellowish galaxies, only accounts for about one percent of the mass needed to make the observed bluish arcing images of background galaxies. In fact, most of the gravitational mass required to warp space enough to explain this cosmic scale lensing is in the form of still mysterious dark matter. As the dominant source of Abell 1689's gravity, the dark matter's unseen presence is mapped out by the lensed arcs and distorted background galaxy images. Surprisingly, close inspection of the above image has revealed the presence of over 100,000 globular star clusters in the galaxy cluster.

September 16, 2013

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No one, presently, sees the Moon rotate like this. That's because the Earth's moon is tidally locked to the Earth, showing us only one side. Given modern digital technology, however, combined with many detailed images returned by the Lunar Reconnaissance Orbiter (LRO), a high resolution virtual Moon rotation movie has now been composed. The above time-lapse video starts with the standard Earth view of the Moon. Quickly, though, Mare Orientale, a large crater with a dark center that is difficult to see from the Earth, rotates into view just below the equator. From an entire lunar month condensed into 24 seconds, the video clearly shows that the Earth side of the Moon contains an abundance of dark lunar maria, while the lunar far side is dominated by bright lunar highlands. Two new missions are scheduled to begin exploring the Moon within the year, the first of which is NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE). LADEE, which launched just over a week ago, is scheduled to begin orbiting the Moon in October and will explore the thin and unusual atmosphere of the Moon. In a few months, the Chinese Chang'e 3 is scheduled to launch, a mission that includes a soft lander that will dispatch a robotic rover.

September 15, 2013

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Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and M2-9 pictured above, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes. The expended gas frequently forms an impressive display called a planetary nebula that fades gradually over thousand of years. M2-9, a butterfly planetary nebula 2100 light-years away shown in representative colors, has wings that tell a strange but incomplete tale. In the center, two stars orbit inside a gaseous disk 10 times the orbit of Pluto. The expelled envelope of the dying star breaks out from the disk creating the bipolar appearance. Much remains unknown about the physical processes that cause planetary nebulae.

September 14, 2013

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With parachute deployed and retro-rockets blazing, this spacecraft landed on planet Earth on September 11 (UT) in a remote area near the town of Zhezkazgan, Kazakhstan. Seen in silhouette against the rockets' glare, the spacecraft is a Soyuz TMA-08M. Its crew, Expedition 36 Commander Pavel Vinogradov and Flight Engineer Alexander Misurkin of the Russian Federal Space Agency (Roscosmos), and Flight Engineer Chris Cassidy of NASA were returning after five and half months aboard the International Space Station. The Soyuz retro-rockets fire very quickly and for an extremely short duration near touchdown. Capturing the moment, the well-timed photograph was taken from a helicopter flying over the landing site.

September 13, 2013

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On September 8, brilliant planet Venus appearing as the evening star stood near a slender, crescent Moon at sunset. The close celestial pairing or conjunction was a scene enjoyed by skygazers around the world. But from some locations in South America, the Moon actually passed in front of Venus in a lunar occultation. Captured near Las Cañas, Uruguay, this two frame mosaic telescopic view shows the Moon and Venus before and after the occultation. The silvery evening star appears at right just before it winked out behind the dark lunar limb, still in bright twilight skies. About an hour later Venus emerged (left) along the three day old Moon's sunlit edge.

September 12, 2013

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Cosmic dust clouds sprawl across a rich field of stars in this sweeping telescopic vista near the northern boundary of Corona Australis, the Southern Crown. Less than 500 light-years away the dust clouds effectively block light from more distant background stars in the Milky Way. The entire frame spans about 2 degrees or over 15 light-years at the clouds' estimated distance. Near center is a group of lovely reflection nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. A characteristic blue color is produced as light from hot stars is reflected by the cosmic dust. The dust also obscures from view stars in the region still in the process of formation. Smaller yellowish nebula NGC 6729 surrounds young variable star R Coronae Australis. Below it are arcs and loops identified as Herbig Haro objects associated with energetic newborn stars. Magnificent globular star cluster NGC 6723 is at the right. Though NGC 6723 appears to be part of the group, its ancient stars actually lie nearly 30,000 light-years away, far beyond the young stars of the Corona Australis dust clouds.

September 11, 2013

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On September 6, a starry night and the Milky Way witnessed the launch of a Minotaur V rocket from NASA's Wallops Flight Facility on Wallops Island, Virginia. So did a large part of the eastern United States, as the spectacular night launch was easily visible even from light polluted urban areas. This 35 second exposure captures part of the rocket's initial launch streak and 2nd stage ignition flare along with a brilliant reflection of the fiery sky in calm waters. The stunning view faces south and west from a vantage point overlooking Sinepuxent Bay in Maryland about 20 miles north of the launch pad. Heading east over the Atlantic, the multi-stage rocket placed LADEE, the Lunar Atmosphere and Dust Environment Explorer, into a highly elliptical Earth orbit to begin its journey to the Moon.

September 10, 2013

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It is one of the most important stars in the sky. This is partly because, by coincidence, it is surrounded by a dazzling reflection nebula. Pulsating RS Puppis, the brightest star in the image center, is some ten times more massive than our Sun and on average 15,000 times more luminous. In fact, RS Pup is a Cepheid type variable star, a class of stars whose brightness is used to estimate distances to nearby galaxies as one of the first steps in establishing the cosmic distance scale. As RS Pup pulsates over a period of about 40 days, its regular changes in brightness are also seen along the nebula delayed in time, effectively a light echo. Using measurements of the time delay and angular size of the nebula, the known speed of light allows astronomers to geometrically determine the distance to RS Pup to be 6,500 light-years, with a remarkably small error of plus or minus 90 light-years. An impressive achievement for stellar astronomy, the echo-measured distance also more accurately establishes the true brightness of RS Pup, and by extension other Cepheid stars, improving the knowledge of distances to galaxies beyond the Milky Way. The above image was taken by the Hubble Space Telescope and digitally processed by a volunteer.

September 9, 2013

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It was late in the northern martian spring when the HiRISE camera onboard the Mars Reconnaissance Orbiter spied this local denizen. Tracking south and east (down and right) across the flat, dust-covered Amazonis Planitia the core of the whirling dust devil is about 30 meters in diameter. Lofting dust into the thin martian atmosphere, its plume reaches more than 800 meters above the surface. Not following the path of the dust devil, the plume is blown toward the east by a westerly breeze. Common in this region, dust devils occur as the surface is heated by the Sun, generating warm, rising air currents that begin to rotate. Tangential wind speeds of up to 110 kilometers per hour are reported for dust devils in other HiRISE images.

September 8, 2013

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The Rim Fire overlapping Yosemite National Park has now burned more than a quarter of a million acres (390 sq. miles), and according to the US Forest Service it may continue to grow, thanks to low humidity and other conditions. Smoke from the wildfire is affecting an even greater area. On Sept. 1st, the students of Earth to Sky Calculus sent a camera to the edge of space for a wide-angle shot of the smokey plumes. This photo, which was taken from the payload of a helium balloon 110,000 feet above Earth's surface, captures more than 10,000 sq. miles of terrain. About half is covered with filaments of smoke from the Rim Fire. There is far more smoke in the image than cumulus clouds. In recent weeks, shifting wind patterns have drawn the plumes back and forth across the mountain towns of the eastern Sierra Nevada, prompting frequent air quality warnings in some places. This photo shows that helium balloons can be effective tools for monitoring the location of the smoke. The black bars and popped red balloon jutting into the top of the photo are part of another ongoing experiment. The students have been dispersing small amounts of powder and ash into the stratosphere to measure the "hang time" of tiny particles. The particles ascend inside a small balloon, which pops at altitude to scatter its contents at the edge of space. As NASA studies of an exploding asteroid over Russia have confirmed, fine ash deposited in the stratosphere does not immediately fall to the ground. It circles the globe for months or more, usually landing harmlessly in remote ocean areas.

September 7, 2013

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This forest of snow and ice penitentes reflects moonlight shinning across the Chajnantor plateau. The region lies in the Chilean Andes at an altitude of 5,000 meters, not far from one of planet Earth's major astronomical observatories, the Atacama Large Millimeter/submillimeter Array. Up to several meters high, the flattened, sharp-edged shapes, and orientation of the penitentes tend to minimize their shadows at local noon. In the dry, cold, thin atmosphere, sublimation driven by sunlight is important for their formation. A direct transition from a solid to a gaseous state, sublimation shapes other solar system terrains too, like icy surfaces of comets and the polar caps of Mars. Above the dreamlike landscape stretches the southern night sky. Their own forms rooted in myth, look for the constellations Pegasus, Andromeda, and Perseus near the panorama's left edge. Bright and colorful stars of Orion the Hunter are near center, with the Large Magellanic Cloud and the South Celestial Pole on the far right.

September 6, 2013

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Hot gas is hard to swallow. At least that seems to be true for the supermassive black hole at the center of our Milky Way Galaxy. Known as source Sagittarius A*, the Milky Way's black hole is centered in this infrared (red and yellow hues) and X-ray (blue) composite. Based on data from an extensive campaign of observations by the orbiting Chandra X-ray telescope, the diffuse emission surrounding the black hole is seen in the close-up inset, the inset field spanning about 1/2 light-year across the galactic center some 26,000 light-years away. Astronomers have found that the X-ray emission originates in hot gas drawn from the winds of massive young stars in the region. The Chandra data indicate that only about 1% or less of the gas within the black hole's gravitational influence ever reaches the event horizon, losing enough heat and angular momentum to fall into the black hole, while the rest of the gas escapes in an outflow. The result explains why the Milky Way's black hole is so quiet, much fainter than might be expected in energetic X-rays. It likely holds for most supermassive black holes in galaxies in the nearby Universe. The Chandra X-Ray Observatory has a supplemental explanation found here: http://chandra.harvard.edu/blog/node/452

September 5, 2013

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The Crab Nebula is cataloged as M1, the first on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, an expanding cloud of debris from the explosion of a massive star. The violent birth of the Crab was witnessed by astronomers in the year 1054. Roughly 10 light-years across today, the nebula is still expanding at a rate of over 1,000 kilometers per second. Want to see the Crab Nebula expand? Compare an image of M1 taken in 1999 at the European Southern Observatory, with this one, taken in 2012 at the Mt. Lemmon Sky Center. Background stars were used to register the two images. The Crab Nebula lies about 6,500 light-years away in the constellation Taurus. The 1999 image is found below. Look closely at the stars to either side of the Crab Nebula on both pictures.

http://www.eso.org/public/images/eso9948f/

September 4, 2013

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Will this caterpillar-shaped interstellar cloud one day evolve into a butterfly-shaped nebula? No one is sure. What is sure is that IRAS 20324+4057, on the inside, is contracting to form a new star. On the outside, however, energetic winds are blowing and energetic light is eroding away much of the gas and dust that might have been used to form the star. Therefore, no one is sure what mass the resulting star will have, and, therefore, no one knows the fate of this star. Were the winds and light to whittle the protostar down near the mass of the Sun, the outer atmosphere of this new star may one day expand into a planetary nebula, possibly even one that looks like a butterfly. Alternatively, if the stellar cocoon retains enough mass, a massive star will form that will one day explode in a supernova. The eroding protostellar nebula IRAS 20324+4057 spans about one light year and lies about 4,500 light years away toward the constellation of the Swan (Cygnus). The above image of IRAS 20324+4057 was taken with the Hubble Space Telescope in 2006 but released last week. The battle between gravity and light will likely take over 100,000 years to play out, but clever observations and deductions may yet yield telling clues well before that.

September 3, 2013

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Here lie familiar shapes in unfamiliar locations. On the left is an emission nebula cataloged as NGC 7000, famous partly because it resembles our fair planet's continent of North America. The emission region to the right of the North America Nebula is IC 5070, also known for its suggestive outlines as the Pelican Nebula. Separated by a dark cloud of obscuring dust, the two bright nebulae are about 1,500 light-years away. At that distance, the 4 degree wide field of view spans 100 light-years. This spectacular cosmic portrait combines narrow band images to highlight bright ionization fronts with fine details of dark, dusty forms in silhouette. Emission from atomic hydrogen, sulfur, and oxygen is captured in the narrow band data. These nebulae can be seen with binoculars from a dark location. Look northeast of bright star Deneb in the constellation of Cygnus the Swan.

September 2, 2013

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What's that below the Milky Way? First, across the top of the above image, lies the faint band that is our planet's sideways view of the central disk of our home Milky Way Galaxy. The Milky Way band can be seen most clear nights from just about anywhere on Earth with a dark sky. What lies beneath is, by comparison, is a much less common sight. It is the striking peak of Castildetierra, a rock formation located in Bardenas Reales, a natural badlands in northeast Spain. Standing 50 meters tall, the rock spire includes clay and sandstone left over from thousands of years of erosion by wind and water. The astrophotographer waited months for the sky to appear just right - and then took the 14 exposures that compose the above image in a single night.

September 1, 2013

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On June 4, 2010 Regulus, alpha star of the constellation Leo, and wandering planet Mars were at about the same apparent brightness, separated on the sky by 1.5 degrees. An ingenious and creative 10 second exposure from a swinging camera recorded these gyrating trails of the celestial pairing. Can you tell which trail belongs to the star and which to the planet? Hint: atmospheric turbulence causes the image of the star to scintillate or vary in brightness and color more readily than the planet. The scintillation is more pronounced because the star is effectively a point source of light seen as a narrow bundle of light rays. Rapidly changing refraction due to turbulence along the line of sight affects different colors of light by different amounts and generally produces a twinkling effect for stars. But Mars is much closer than the distant stars and an extended source of light. Though tiny, its disk is seen as a bundle of light rays that is substantially broader compared to a star's and so, on average, less affected by small scale turbulence. The result is the varied, rainbow like trail for Regulus (left) and the steadier, consistently reddish trail for Mars.

August 31, 2013

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Dwarf galaxy NGC 5195 is best known as the smaller companion of spiral M51, the Whirlpool galaxy. Seen together they seem to trace the curve and dot of a cosmic question mark, recorded in Lord Rosse's 19th century drawings as one of the original spiral nebulae. Dwarfed by enormous M51 (aka NGC 5194), NGC 5195 spans about 20,000 light-years. A close encounter with M51 has likely triggered star formation and enhanced that galaxy's prominent spiral arms. Processed from image data available in the Hubble Legacy Archive, this majestic close-up of NGC 5195 makes it clear that the dwarf galaxy now lies behind M51. A tidal bridge of dark dust clouds and young blue star clusters stretches from the outskirts of M51 on the right, appearing in silhouette against the dwarf galaxy's yellowish glow. The famous pair of interacting galaxies lie some 30 million light-years away, toward the handle of the Big Dipper, and the constellation of the Hunting Dogs.

August 30, 2013

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These three bright nebulae are often featured in telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the large nebula left of center, and colorful M20 on the right. The third, NGC 6559, is above M8, separated from the larger nebula by a dark dust lane. All three are stellar nurseries about five thousand light-years or so distant. The expansive M8, over a hundred light-years across, is also known as the Lagoon Nebula. M20's popular moniker is the Trifid. Glowing hydrogen gas creates the dominant red color of the emission nebulae, with contrasting blue hues, most striking in the Trifid, due to dust reflected starlight. The colorful skyscape recorded with telescope and digital camera also includes one of Messier's open star clusters, M21, just above the Trifid.

August 29, 2013

Source: My Camera
Since Nova Delphinii erupted on August 14th, it has been photographed by both professional and amateur astronomers. Peaking on August 16th at magnitude 4.5, I became one of the photographers when I captured the Nova in the outskirts of Toronto, although I couldn't physically see it with the amount of lgiht pollution around. Fortunately, cameras have better eyes than I do, and on August 17th I was able to confirm the Nova was around magnitude 4.5 by comparing it to relative stars. This picture is both shown with annotations and without annotations in the first two pictures. Last night on August 28, 2013 from the much darker town of Wasaga Beach, I sought out to capture a much fainter Nova at magnitude 6.3. Using the same amount of stacked images as the previous expedition, the effect of light pollution and the dimming Nova are both clear in the two comparitive pictures. All background stars are notably brighter in the wasaga Beach photos. The best way to note the change in brightness of the Nova is to look at the 'triangle' of roughly equal stars above, and just below to the left and right of the Nova. In the August 17 picture, the Nova is considerably brighter. In the picture from last night, they appear roughly the same. The light curve below shows the gradual dimming of the Nova since the peak.

August 28, 2013

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What type of cloud is that? This retreating cumulonimbus cloud, more commonly called a thundercloud, is somewhat unusual as it contains the unusual bumpiness of a mammatus cloud on the near end, while simultaneously producing falling rain on the far end. Taken in mid-June in southern Alberta, Canada, the cloud is moving to the east, into the distance, as the sun sets in the west, behind the camera. In the above image, graphic sunset colors cross the sky to give the already photogenic cloud striking orange and pink hues. A darkening blue sky covers the background. Further in the distance, a rising, waxing, gibbous moon is visible on the far right.

August 27, 2013

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To the human eye, a nearby flash of lightning looks blindingly white. But have you ever wondered what colors might emerge if the flash were spread out chromatically, like a rainbow? During a recent thunderstorm in Tarn, France, David Antao decided to find out. "I am an enthusiastic astro-spectroscopist," he says, "so I couldn't resist shooting some spectra." All of the colors of a rainbow are present in the lightning strike, but some colors are stronger than others. Red, green and blue emission lines zig-zag across the spectrum tracing the shape of the original bolt. These colors are mainly due to the recombination of electrons with nitrogen molecules broken apart and ionized by the searing heat of the lightning discharge. Lines from oxygen, hydrogen, and nitrogen oxides are present, too. "By analysing this spectra, it is possible to determine the temprature of the lightning," notes Antao. "I am trying to do this now."

August 26, 2013

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It is one of the brightest planetary nebulae on the sky - what should it be named? First discovered in 1878, nebula NGC 7027 can be seen toward the constellation of the Swan (Cygnus) with a standard backyard telescope. Partly because it appears there as only an indistinct spot, it is rarely referred to with a moniker. When imaged with the Earth-orbiting Hubble Space Telescope, however, great details are revealed. Studying Hubble images of NGC 7027 have led to the understanding that it is a planetary nebula that began expanding about 600 years ago, and that the cloud of gas and dust is unusually massive as it appears to contain about three times the mass of our Sun. Pictured above in assigned colors, the resolved, layered, and dust-laced features of NGC 7027 might remind sky enthusiasts of a familiar icon that could be the basis for an informal name. Please feel free to make suggestions - some suggestions are being recorded, for example, in an online APOD discussion forum found here; http://asterisk.apod.com/viewtopic.php?f=9&t=31990

August 25, 2013

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What will become of these galaxies? Spiral galaxies NGC 5426 and NGC 5427 are passing dangerously close to each other, but each is likely to survive this collision. Typically when galaxies collide, a large galaxy eats a much smaller galaxy. In this case, however, the two galaxies are quite similar, each being a sprawling spiral with expansive arms and a compact core. As the galaxies advance over the next tens of millions of years, their component stars are unlikely to collide, although new stars will form in the bunching of gas caused by gravitational tides. Close inspection of the above image taken by the 8-meter Gemini-South Telescope in Chile shows a bridge of material momentarily connecting the two giants. Known collectively as Arp 271, the interacting pair spans about 130,000 light years and lies about 90 million light-years away toward the constellation of Virgo. Recent predictions hold that our Milky Way Galaxy will undergo a similar collision with the neighboring Andromeda Galaxy in a few billion years.

August 24, 2013

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This friendly photo collage is constructed from more than 1,400 images shared by denizens of planet Earth as part of the Cassini Mission's July 19th Wave at Saturn event. The base picture of Earth corresponds to the view from the Saturn-orbiting Cassini spacecraft on that date as its own cameras recorded images including planet Earth as a pale blue dot in the background. Of course, Saturn was 9.65 Astronomical Units away at the time, so it took light from all the waving Earth dwellers just over 80 minutes to travel there. Want to smile? Download and zoom in to the full-resolution (28MB jpg file) collage image available here.

August 23, 2013

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When a new star appeared in the constellation Delphinus late last week, astronomers found its spectrum hinted at the apparition's true nature. Now known as Nova Delphini, its visible light spectrum near maximum brightness is centered in this image of the nearby star field captured with prism and telescope on the night of August 16/17 at the Sternwarte Bülach, Switzerland. Strong absorption lines due to hydrogen atoms are seen as the darkest bands in the nova's spectrum, but the strong absorption lines are bordered along their redward edge by bright bands of emission. That pattern is the spectral signature of material blasted from a catalysmic binary system known as a classical nova. Other stars in field are fainter, identified by their Hipparcus catalog numbers, brightness in magnitudes, and spectral types. By chance, the faint emission line from planetary nebula NGC 6905 was also included, indicated at the lower right.

August 22, 2013

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The prominent ridge of emission featured in this dramatic skyscape is cataloged as IC 5067. Part of a larger emission nebula with a distinctive shape, popularly called The Pelican Nebula, the ridge spans about 10 light-years following the curve of the cosmic pelican's head and neck. This false color view also translates the pervasive glow of narrow emission lines from atoms in the nebula to a color palette made popular in Hubble Space Telescope images of star forming regions. Fantastic, dark shapes inhabiting the 1/2 degree wide field are clouds of cool gas and dust sculpted by the winds and radiation from hot, massive stars. Close-ups of some of the sculpted clouds show clear signs of newly forming stars. The Pelican Nebula, itself cataloged as IC 5070, is about 2,000 light-years away. To find it, look northeast of bright star Deneb in the high flying constellation Cygnus.

August 21, 2013

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Comet dust rained down on planet Earth earlier this month, streaking through dark skies in the annual Perseid meteor shower. While enjoying the anticipated space weather above Zhangbei Prairie, Hebei Province, China, astronomer Xiang Zhan recorded a series of 10 second long exposures spanning four hours on the night of August 12/13 using a wide angle lens. Combining frames which captured 68 meteor flashes, he produced the above composite view of the Perseids of summer. Although the sand-sized comet particles are traveling parallel to each other, the resulting shower meteors clearly seem to radiate from a single point on the sky in the eponymous constellation Perseus. The radiant effect is due to perspective, as the parallel tracks appear to converge at a distance. The next notable meteor shower may be the Orionids in late October.

August 20, 2013

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An unusual type of solar eclipse occurred last year. Usually it is the Earth's Moon that eclipses the Sun. Last June, most unusually, the planet Venus took a turn. Like a solar eclipse by the Moon, the phase of Venus became a continually thinner crescent as Venus became increasingly better aligned with the Sun. Eventually the alignment became perfect and the phase of Venus dropped to zero. The dark spot of Venus crossed our parent star. The situation could technically be labeled a Venusian annular eclipse with an extraordinarily large ring of fire. Pictured above during the occultation, the Sun was imaged in three colors of ultraviolet light by the Earth-orbiting Solar Dynamics Observatory, with the dark region toward the right corresponding to a coronal hole. Hours later, as Venus continued in its orbit, a slight crescent phase appeared again. The next Venusian solar eclipse will occur in 2117.

August 19, 2013

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Why would the sky still glow after sunset? Besides stars and the band of our Milky Way galaxy, the sky might glow because it contains either noctilucent clouds or aurora. Rare individually, both are visible in the above time lapse movie taken over Caithness, Scotland, UK taken during a single night earlier this month. First noted in 1885, many noctilucent clouds are known to correlate with atmospheric meteor trails, although details and the origins of others remain a topic of research. These meandering bright filaments of sunlight-reflecting ice crystals are the highest clouds in the Earth's atmosphere. The above video captures not only a variety of noctilucent clouds, but also how their structure varies over minutes. Lower clouds typically appear dark or fast moving. About halfway through the video the clouds are joined by aurora. At times, low clouds, noctilucent clouds, and aurora are all visible simultaneously, each doing their own separate dance, and once - see if you can find it - even with the Big Dipper rotating across the background.

August 18, 2013

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Skylab was an orbiting laboratory launched by a Saturn V rocket in May 1973. Skylab, pictured above, was visited three times by NASA astronauts who sometimes stayed as long as two and a half months. Many scientific tests were performed on Skylab, including astronomical observations in ultraviolet and X-ray light. Some of these observations yielded valuable information about Comet Kohoutek, our Sun and about the mysterious X-ray background - radiation that comes from all over the sky. Skylab fell back to earth on 1979 July 11.

August 17, 2013

Source: My Camera
The Delphinus Nova last night was visible in binoculars in even the brightest of cities in Canada, including Toronto. This composite image is a 51 picture stack of the Delphinus Nova, taken around 10;47pm EST. I was unable to spot the nova without optical aids, but it was visible through my camera lens. The bright moon had washed out a lot of the fainter objects in this area of the sky, but a satellite decided to nicely frame itself while I was taking pictures. The Nova's magnitude can be found using this link from AAVSO: http://www.aavso.org/lcg/plot?auid=0...=&mean=&vmean=

August 16, 2013

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Using a small telescope to scan the skies on August 14, Japanese amateur astronomer Koichi Itagaki discovered a "new" star within the boundaries of the constellation Delphinus. Indicated in this skyview captured on August 15 from Stagecoach, Colorado, it is now appropriately designated Nova Delphini 2013. Sagitta, the Arrow, points the way to the newcomer's location high in the evening sky, not far from bright star Altair and the asterism known to northern hemisphere skygazers as the Summer Triangle. The nova is reported to be easy to spot with binoculars, near the limit of naked-eye visibility under dark skies. In fact, previous deep sky charts do show a much fainter known star (about 17th magnitude) at the position of Nova Delphini, indicating this star's apparent brightness suddenly increased over 25,000 times. How does a star undergo such a cataclysmic change? The spectrum of Nova Delphini indicates it is a classical nova, an interacting binary star system in which one star is a dense, hot white dwarf. Material from a cool, giant companion star falls onto the surface of the white dwarf, building up until it triggers a thermonuclear event. The drastic increase in brightness and an expanding shell of debris is the result - but the stars are not destroyed! Classical novae are believed to recur when the flow of material onto the white dwarf resumes and produces another outburst.

August 15, 2013

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In an astronomical version of the search for the source of the Nile, astronomers now have strong evidence for the origin of the Magellanic Stream. This composite image shows the long ribbon of gas, discovered at radio wavelengths in the 1970s, in pinkish hues against an optical all-sky view across the plane of our Milky Way galaxy. Both Large and Small Magellanic Clouds, dwarf satellite galaxies of the the Milky Way, are seen near the head of the stream at the right. Data from Hubble's Cosmic Origins Spectrograph were used to explore abundances of elements along sitelines to quasars that intersect the stream. The results indicate that most of the stream's material comes from the Small Magellanic Cloud. The Magellanic Stream is likely the result of gravitational tidal interactions between the two dwarf galaxies some 2 billion years ago, the Small Magellanic Cloud losing more material in the encounter because of its lower mass.

August 14, 2013

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It took three worlds to create this simple image. The first world was the Earth, which was quite prominent. The dividing line running horizontally below the middle separates sea from sky. On this part of the Earth, it was almost nighttime. The second world was the Moon, which was almost invisible. The Moon had its unilluminated half masked by the red sunset glow of Earth's sky. A thin sliver of the new Moon was visible, a crescent that traces the bright curving line. The third world was the Sun, which does not appear directly. All of the light recorded in the image originated from the Sun. The above half-second exposure was taken last week from Anping, Taiwan. A few minutes after this image was taken the Earth had spun just a little bit further - forcing the Moon to follow the Sun into the sea - and the horizon to become dark.

August 13, 2013

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Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Perseus. That is why the meteor shower that peaked over the past few days is known as the Perseids - the meteors all appear to come from a radiant toward Perseus. Three dimensionally, however, sand-sized debris expelled from Comet Swift-Tuttle follows a well-defined orbit about our Sun, and the part of the orbit that approaches Earth is superposed in front of the Perseus. Therefore, when Earth crosses this orbit, the radiant point of falling debris appears in Perseus. Pictured above, a composite of 13 early images from this year's Pereids meteor shower shows many bright meteors that streaked through the sky the night of August 11 near Oakland, Ontario, Canada.

August 12, 2013

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Are asteroids dangerous? Some are, but the likelihood of a dangerous asteroid striking the Earth during any given year is low. Because some past mass extinction events have been linked to asteroid impacts, however, humanity has made it a priority to find and catalog those asteroids that may one day affect life on Earth. Pictured above are the orbits of the over 1,000 known Potentially Hazardous Asteroids (PHAs). These documented tumbling boulders of rock and ice are over 140 meters across and will pass within 7.5 million kilometers of Earth - about 20 times the distance to the Moon. Although none of them will strike the Earth in the next 100 years - not all PHAs have been discovered, and past 100 years, many orbits become hard to predict. Were an asteroid of this size to impact the Earth, it could raise dangerous tsunamis, for example. Of course rocks and ice bits of much smaller size strike the Earth every day, usually pose no danger, and sometimes creating memorable fireball and meteor displays.

August 11, 2013

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If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 32 million light-years away toward the constellation Pisces, M74 presents a gorgeous face-on view. Classified as an Sc galaxy, the grand design of M74's graceful spiral arms are traced by bright blue star clusters and dark cosmic dust lanes. Constructed from image data recorded in 2003 and 2005, this sharp composite is from the Hubble Space Telescope's Advanced Camera for Surveys. Spanning about 30,000 light-years across the face of M74, it includes exposures recording emission from hydrogen atoms, highlighting the reddish glow of the galaxy's large star-forming regions. Recently, many astronomers are tracking a bright supernova that has been seen in M74.

August 10, 2013

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The two bright meteors flashing through this night skyscape from August 7 are part of the ongoing Perseid meteor shower. In the direction indicated by both colorful streaks, the shower's radiant in the eponymous constellation Perseus is at the upper right. North star Polaris, near the center of all the short, arcing star trails is at the upper left. But also named for its pose against the sky, the monastery built on the daunting sandstone cliffs in the foreground is part of Meteora. A World Heritage site, Meteora is a historic complex of lofty monasteries located near Kalabaka in central Greece.
Previous Pictures of the Day:

August 9, 2013

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Medieval Albrechtsberg castle is nestled in trees near the northern bank of the river Pielach and the town of Melk, Austria. In clearing night skies on August 12, 2012 it stood under constellations of the northern summer, including Aquarius, Aquila, and faint, compact Delphinus (above and right of center) in this west-looking skyview. The scene also captures a bright meteor above the castle walls. Part of the annual perseid meteor shower, its trail points back toward the heroic constellation Perseus high above the horizon in the early morning hours. Entering the atmosphere at about 60 kilometers per second, perseid meteors are swept up dust grains from the tail of comet Swift-Tuttle. Of course, this year's perseid meteors will flash through night skies this weekend.

August 8, 2013

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Similar in size and grand design to our own Milky Way, spiral galaxy NGC 3370 lies about 100 million light-years away toward the constellation Leo. Recorded here in exquisite detail by the Hubble Space Telescope's Advanced Camera for Surveys, the big, beautiful face-on spiral does steal the show, but the sharp image also reveals an impressive array of background galaxies in the field, strewn across the more distant Universe. Looking within NGC 3370, the image data has proved sharp enough to study individual pulsating stars known as Cepheids that can be used to accurately determine this galaxy's distance. NGC 3370 was chosen for this study because in 1994 the spiral galaxy was also home to a well studied stellar explosion - a type Ia supernova. Combining the known distance to this standard candle supernova, based on the Cepheid measurements, with observations of supernovae at even greater distances, can reveal the size and expansion rate of the Universe itself.

August 7, 2013

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What's going on behind that volcano? Quite a bit. First of all, the volcano itself, named Kirkjufell, is quite old and located in western Iceland near the town of Grundarfjörður. In front of the steeply-sloped structure lies a fjord that had just begun to freeze when the above image was taken - in mid-December of 2012. Although quite faint to the unaided eye, the beautiful colors of background aurorae became quite apparent on the 25-second exposure. What makes this image is of particular note, though, is that it also captures streaks from the Geminids meteor shower - meteors that might not have been evident were the aurora much brighter. Far in the distance, on the left, is the band of our Milky Way Galaxy, while stars from our local part of the Milky Way appear spread across the background. This weekend the Perseids meteor shower will peak and may well provide sky enthusiasts with their own memorable visual experiences.

August 6, 2013

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Strange shapes and textures can be found in neighborhood of the Cone Nebula. The unusual shapes originate from fine interstellar dust reacting in complex ways with the energetic light and hot gas being expelled by the young stars. The brightest star on the right of the above picture is S Mon, while the region just below it has been nicknamed the Fox Fur Nebula for its color and structure. The blue glow directly surrounding S Mon results from reflection, where neighboring dust reflects light from the bright star. The red glow that encompasses the whole region results not only from dust reflection but also emission from hydrogen gas ionized by starlight. S Mon is part of a young open cluster of stars named NGC 2264, located about 2500 light years away toward the constellation of the Unicorn (Monoceros). Even though it points right at S Mon, details of the origin of the mysterious geometric Cone Nebula, visible on the far left, remain a mystery.

August 5, 2013

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What it would look like to leave planet Earth? Such an event was recorded visually in great detail by the MESSENGER spacecraft as it swung back past the Earth, eight years ago, on its way in toward the planet Mercury. Earth can be seen rotating in this time-lapse video, as it recedes into the distance. The sunlit half of Earth is so bright that background stars are not visible. The robotic MESSENGER spacecraft is now in orbit around Mercury and has recently concluded the first complete map of the surface. On occasion, MESSENGER has continued to peer back at its home world. MESSENGER is one of the few things created on the Earth that has left and will never return - at the end of its mission MESSENGER will be crashed into Mercury's surface.

August 4, 2013

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Like the downtown area of your favorite city and any self-respecting web site, Io's surface is constantly under construction. This moon of Jupiter holds the distinction of being the Solar System's most volcanically active body - its bizarre looking surface continuously formed and reformed by lava flows. Generated using 1996 data from NASA's Galileo spacecraft, this high resolution composite image is centered on the side of Io that always faces away from Jupiter. It has been enhanced to emphasize Io's surface brightness and color variations, revealing features as small as 1.5 miles across. The notable absence of impact craters suggests that the entire surface is covered with new volcanic deposits much more rapidly than craters are created. What drives this volcanic powerhouse? A likely energy source is the changing gravitational tides caused by Jupiter and the other Galilean moons as Io orbits the massive gas giant planet. Heating Io's interior, the pumping tides would generate the sulfurous volcanic activity.

August 3, 2013

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A careful look at this colorful cosmic snapshot reveals a surprising number of galaxies both near and far toward the constellation Ursa Major. The most striking is NGC 3718, the warped spiral galaxy near picture center. NGC 3718's spiral arms look twisted and extended, mottled with young blue star clusters. Drawn out dust lanes obscure its yellowish central regions. A mere 150 thousand light-years to the right is another large spiral galaxy, NGC 3729. The two are likely interacting gravitationally, accounting for the peculiar appearance of NGC 3718. While this galaxy pair lies about 52 million light-years away, the remarkable Hickson Group 56 can also be seen clustered above NGC 3718, near the top of the frame. Hickson Group 56 consists of five interacting galaxies and lies over 400 million light-years away. This picture was chosen as the overall winner in the 2013 David Malin Astrophotography Competition.

August 2, 2013

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This intriguing monument can be found in Taiwan between the cities of Hualian and Taitong. Split into two sides, it straddles a special circle of latitude on planet Earth, near 23.5 degrees north, known as the Tropic of Cancer. Points along the Tropic of Cancer are the northernmost locations where the Sun can pass directly overhead, an event that occurs once a year during the northern hemisphere's summer solstice. The latitude that defines the Tropic of Cancer corresponds to the tilt of planet Earth's rotation axis with respect to its orbital plane. The name refers to the zodiacal constellation Cancer the Crab. Historically the Sun's position was within Cancer during the northern summer solstice, but because of the precession of Earth's axis, that solstice Sun is currently within the boundaries of Taurus. In this starry night scene the otherwise all white structure is colored by city lights, with its orange side just south of the Tropic of Cancer and the white side just north. Of course, there is a southern hemisphere counterpart of the Tropic of Cancer called the Tropic of Capricorn.

August 1, 2013

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The Great Spiral Galaxy in Andromeda (aka M31), a mere 2.5 million light-years distant, is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small, faint, fuzzy patch, but because its surface brightness is so low, casual skygazers can't appreciate the galaxy's impressive extent in planet Earth's sky. This entertaining composite image compares the angular size of the nearby galaxy to a brighter, more familiar celestial sight. In it, a deep exposure of Andromeda, tracing beautiful blue star clusters in spiral arms far beyond the bright yellow core, is combined with a typical view of a nearly full Moon. Shown at the same angular scale, the Moon covers about 1/2 degree on the sky, while the galaxy is clearly several times that size. The deep Andromeda exposure also includes two bright satellite galaxies, M32 and M110 (bottom).

[ic0slay3r]

Re: Terry's Astronomy Thread.

Those chairs looks uncomfortable :s Also is there really a need for that many buttons? I have a feeling that at least 70% of them are not even touched once the shuttle is in the air, unless there is some kind of malfunction somewhere.

[Bluearrowll]

Re: Terry's Astronomy Thread.

While I am unsure what 99% of those buttons do, I imagine to an extent they're symmetrical so that both people sitting at the front can hit the same ones if they needed to.

What's in the sky tonight?
April 19, 2012

-Bright Vega is now visible low in the northeast as early as 9:30 or 10 p.m. (depending on where you live). Bright Arcturus dominates the high sky due east. Look a third of the way from Arcturus to Vega for dim Corona Borealis, the Northern Crown, with its one modestly bright star, Alphecca. Look two-thirds of the way from Arcturus to Vega for the dimmer Keystone of Hercules.

-Keep an eye out for the weak but unpredictable meteor shower which will peak saturday night-sunday morning. Read here for more.

Astro Picture of the Day:
April 19, 2012

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Climbing into cloudy skies, the Space Shuttle Orbiter Discovery (OV-103) took off from Kennedy Space Center Tuesday at 7 am local time. This time, its final departure from KSC, it rode atop a modified Boeing 747 Shuttle Carrier Aircraft. Following a farewell flyover of the Space Coast, Goddard Space Flight Center, and Washington DC, Discovery headed for Dulles International Airport in Virginia, destined to reside at the Smithsonian's National Air and Space Museum Udvar-Hazy Center. Discovery retires as NASA's most traveled shuttle orbiter, covering more than 148 million miles in 39 missions that included the delivery of the Hubble Space Telescope to orbit. Operational from 1984 through 2011, Discovery spent a total of one year in space.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 20, 2012

-Capella, Venus, and Aldebaran form an almost perfectly straight line in the western sky this evening and Saturday evening, in that order from upper right to lower left.

-The best time to examine Venus in a telescope is late afternoon or around sundown. It's now a thick crescent 33 arcseconds tall and 33% sunlit, waning and enlarging week by week as it swings closer to Earth. Venus will transit the face of the Sun on June 5–6 (the afternoon of the 5th for North America). A transit is an eclipse that does not completely cover the object because to us, it appears to small. This is the only Venusian transit you will get to experience.

Astro Picture of the Day:
April 20, 2012

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Except for the rings of Saturn, the Ring Nebula (M57) is probably the most famous celestial band. Its classic appearance is understood to be due to perspective - our view from planet Earth looks down the center of a roughly barrel-shaped cloud of glowing gas. But expansive looping structures are seen to extend far beyond the Ring Nebula's familiar central regions in this intriguing composite of ground based and Hubble Space Telescope images with narrowband image data from Subaru. Of course, in this well-studied example of a planetary nebula, the glowing material does not come from planets. Instead, the gaseous shroud represents outer layers expelled from the dying, once sun-like star at the nebula's center. Intense ultraviolet light from the hot central star ionizes atoms in the gas. Ionized oxygen atoms produce the characteristic greenish glow and ionized hydrogen the prominent red emission. The central ring of the Ring Nebula is about one light-year across and 2,000 light-years away. To accompany tonight's shooting stars it shines in the northen constellation Lyra.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 21, 2012

-The weak but unpredictable Lyrid meteor shower should reach maximum activity in the hours before dawn Sunday morning. There will be no Moon. You might see a dozen Lyrids per hour under ideal dark-sky conditions before the beginning of dawn. Find more information about today's meteor shower here.

-New Moon (exact at 3:18 a.m. EDT on the 21st).

Astro Picture of the Day:
April 21, 2012

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These enclosures house 1.8 meter Auxiliary Telescopes (ATs) at Paranal Observatory in the Atacama Desert region of Chile. The ATs are designed to be used for interferometry, a technique for achieving extremely high resolution observations, in concert with the observatory's 8 meter Very Large Telescope units. A total of four ATs are operational, each fitted with a transporter that moves the telescope along a track allowing different arrays with the large unit telescopes. To work as an interferometer, the light from each telescope is then brought to a common focal point by a system of mirrors in underground tunnels. Above these three ATs, the Large and Small Magellanic Clouds are the far far away satellite galaxies of our own Milky Way. In the clear and otherwise dark southern skies, planet Earth's greenish atmospheric airglow stretches faintly along the horizon.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 22, 2012

-Jupiter shines below a very thin crescent Moon very low in the west-northwest in twilight, shown below. Think photo opportunity.

Astro Picture of the Day:
April 22, 2012

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When does Mars act like a liquid? Although liquids freeze and evaporate quickly into the thin atmosphere of Mars, persistent winds may make large sand dunes appear to flow and even drip like a liquid. Visible on the above image right are two flat top mesas in southern Mars when the season was changing from Spring to Summer. A light dome topped hill is also visible on the far left of the image. As winds blow from right to left, flowing sand on and around the hills leaves picturesque streaks. The dark arc-shaped droplets of fine sand are called barchans, and are the interplanetary cousins of similar Earth-based sand forms. Barchans can move intact a downwind and can even appear to pass through each other. When seasons change, winds on Mars can kick up dust and are monitored to see if they escalate into another of Mars' famous planet-scale sand storms.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 23, 2012

-Look for the Pleiades to the right of the thin crescent Moon as twilight deepens, as shown here.

-With Saturn past opposition, say goodbye to the Seeliger effect, the opposition brightening of Saturn's rings. Here is a comparison image to demonstrate the effect.

Astro Picture of the Day:
April 23, 2012

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The unusual blobs found in the Carina nebula, some of which are seen floating on the upper right, might best be described as evaporating. Energetic light and winds from nearby stars are breaking apart the dark dust grains that make the iconic forms opaque. Ironically the blobs, otherwise known as dark molecular clouds, frequently create in their midst the very stars that later destroy them. The floating space mountains pictured above by the orbiting Hubble Space Telescope span a few light months. The Great Nebula in Carina itself spans about 30 light years, lies about 7,500 light years away, and can be seen with a small telescope toward the constellation of Keel (Carina).

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 24, 2012

-Venus is upper right of the crescent Moon this evening.

-Look high to Venus's upper right at dusk for Capella, to its lower left for Aldebaran, and farther to its lower right for the Pleiades. Far beneath Venus, Jupiter is sinking into the sunset.

Astro Picture of the Day:
April 24, 2012

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What's causing those odd rings in supernova 1987A? Twenty five years ago, in 1987, the brightest supernova in recent history was seen in the Large Magellanic Cloud. At the center of the above picture is an object central to the remains of the violent stellar explosion. Surrounding the center are curious outer rings appearing as a flattened figure 8. Although large telescopes including the Hubble Space Telescope monitor the curious rings every few years, their origin remains a mystery. Pictured above is a Hubble image of the SN1987A remnant taken last year. Speculation into the cause of the rings includes beamed jets emanating from an otherwise hidden neutron star left over from the supernova, and the interaction of the wind from the progenitor star with gas released before the explosion.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 25, 2012

-The Moon shines amid (counting clockwise) Pollux and Castor above it, Auriga with Capella to its right, Venus to its lower right, Aldebaran more or less below it, Orion to its lower left, and Procyon farther to its upper left.

-After dusk, three 10th-magnitude asteroids await your probing scope in and around Leo. You will be looking for 5 Astraea, 6 Hebe, and 8 Flora.

Astro Picture of the Day:
April 25, 2012

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Did you see it? One of the more common questions during a meteor shower occurs because the time it takes for a meteor to flash is typically less than the time it takes for a head to turn. Possibly, though, the glory of seeing bright meteors shoot across and knowing that they were once small pebbles on another world might make it all worthwhile, even if your observing partner(s) could not share in every particular experience. Peaking over the past few days, a dark moonless sky allowed the Lyrids meteor shower to exhibit as many as 30 visible meteors per hour from some locations. A bright Lyrid meteor streaks above picturesque Crater Lake in Oregon, USA, in the above composite of nine exposures taken last week. Snow covers the foreground, while the majestic central band of our home galaxy arches well behind the serene lake. Other meteor showers this year include the Perseids in mid-August and the Leonids in mid-November, both expected to also dodge the glare of a bright Moon in 2012.

[Reincarnate]

Re: Terry's Astronomy Thread.

It always blows my mind that the universe is basically a massive dust storm, and that we came from that.