Terry's Astronomy Thread.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 1, 2014

What's in the sky tonight?
July 1, 2014

-Big sunspot AR2104, which emerged over the weekend, has developed a 'beta-gamma-delta' magnetic field that harbors energy for X-class solar flares. So far, however, the sunspot has been relatively quiet, producing no more than a few minor C-flares. Sergio Castillo photographed the brooding giant on June 30th from his backyard observatory in Inglewood, CA. Castillo used a solar telescope capped with a "Calcium-K" filter tuned to 3933 Å, a wavelength that reveals the bright magnetic froth around active sunspots. "The magnetic froth is amazingly visible around AR2104," says Castillo. "I truly hope this active region brings fireworks just in time for the 4th of July."

He might get his wish. NOAA forecasters estimate a growing 40% chance of M-class flares and a 5% chance of X-flares during the next 24 hours. The odds of geoeffective eruptions will increase even more in the days ahead as the sunspot turns toward Earth.

-Ceres and Vesta at their closest. The two leading asteroids, currently magnitudes 8.4 and 7.1, are closing right in on each other as seen on the sky. They're not far above Mars and Spica after dark. They are within 1/3° of each other for the next week and will appear closest together, just 1/6° apart, on the evenings of July 4th and 5th.

Astro Picture of the Day:
July 1, 2014

Source:
Some stars explode in slow motion. Rare, massive Wolf-Rayet stars are so tumultuous and hot that they slowly disintegrate right before our telescopes. Glowing gas globs each typically over 30 times more massive than the Earth are being expelled by violent stellar winds. Wolf-Rayet star WR 124, visible near the above image center spanning six light years across, is thus creating the surrounding nebula known as M1-67. Details of why this star has been slowly blowing itself apart over the past 20,000 years remains a topic of research. WR 124 lies 15,000 light-years away towards the constellation of Sagitta. The fate of any given Wolf-Rayet star likely depends on how massive it is, but many are thought to end their lives with spectacular explosions such as supernovas or gamma-ray bursts.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 2, 2014

What's in the sky tonight?
July 2, 2014

-For people in the northern hemisphere, July is the best time of the year to see noctilucent clouds (NLCs). The month got off to a good start on July 1st when the sunrise over Radebeul, Germany turned electric-blue. "This morning was extremely electric blue over Saxony," says photograher Heiko Ulbricht. "What a great display of noctilucent clouds! I spent much of the night watching the World Cup with friends. At about 2 o'clock in the morning, we drove to a field in Radebeul near the Astronomical Observatory. When the sun came up we were rewarded--a great morning! "

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, when the upper atmosphere is coldest, allowing the ice crystals of NLCs to form.

The natural habitat of noctilucent clouds is the Arctic Circle. In recent years, however, they have spread to lower latitudes with sightings as far south as Utah and Colorado. This will likely happen in 2014 as well. Observing tips: Look west 30 to 60 minutes after sunset when the Sun has dipped 6o to 16o below the horizon. If you see luminous blue-white tendrils spreading across the sky, you may have spotted a noctilucent cloud.

Astro Picture of the Day:
July 2, 2014

Source:
Spiral galaxy NGC 4651 is a mere 62 million light-years distant, toward the well-groomed northern constellation Coma Berenices. About the size of our Milky Way, this island universe is seen to have a faint umbrella-shaped structure that seems to extend (left) some 100 thousand light-years beyond the bright galactic disk. The giant cosmic umbrella is now known to be composed of tidal star streams - extensive trails of stars gravitationally stripped from a smaller satellite galaxy. The small galaxy was eventually torn apart in repeated encounters as it swept back and forth on eccentric orbits through NGC 4651. In fact, the picture insert zooms in on the smaller galaxy's remnant core, identified in an extensive exploration of the system, using data from the large Subaru and Keck telescopes on Mauna Kea. Work begun by a remarkable collaboration of amateur and professional astronomers to image faint structures around bright galaxies suggests that even in nearby galaxies, tidal star streams are common markers of such galactic mergers. The result is explained by models of galaxy formation that also apply to our own Milky Way.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 3, 2014

What's in the sky tonight?
July 3, 2014

-NOAA forecasters estimate a 50% chance of M-class solar flares today. The likely source would be big sunspot AR2104, which has a 'beta-gamma-delta' magnetic field that harbors energy for strong eruptions.

-Yesterday morning at 2:56 AM PDT, NASA's Orbiting Carbon Observatory-2 (OCO-2) blasted into space from the Vandenberg AFB in California. After liftoff, the exhaust from the satellite's Delta II rocket glowed so brightly that Juan Perez was able to see it 500 miles away in Wittmann, Arizona.

Now orbiting Earth, OCO-2 is set to begin a two-plus year mission to locate the sources and sinks of atmospheric carbon dioxide, the leading human-produced greenhouse gas responsible for global warming. The launch was from the west coast so the spacecraft could enter a polar orbit of the Earth, a flight path that will see it cross over the Arctic and Antarctic regions during each revolution and get a complete picture of the Earth. It will fly about 438 miles above the planet's surface to take its readings. While ground stations have been monitoring carbon dioxide concentrations for years, OCO-2 will be the first spacecraft to conduct a global-scale reading over several seasons.

-The sunspot number, already high, ticked upward again today with the arrival of another large active region over the sun's eastern limb. Click to play a 24-hour movie from NASA's Solar Dynamics Observatory. The explosive potential of this new sunspot is unknown. It will come into sharper focus later today and tomorrow as the region turns more directly toward Earth, revealing whether or not AR2109 has the kind of unstable magnetic field that leads to strong flares. For now, solar activty remains low despite the increasing sunspot count.

Astro Picture of the Day:
July 3, 2014

Source:
The prominent ridge of emission featured in this vivid skyscape is known as the Cygnus Wall. Part of a larger emission nebula with a distinctive shape popularly called The North America Nebula, the ridge spans about 10 light-years along an outline that suggests the western coast of Mexico. Constructed from narrowband image data, the cosmic close-up maps emission from sulfur, hydrogen, and oxygen atoms to red, green, and blue colors. The result highlights the bright ionization front with fine details of dark, dusty forms in silhouette. Sculpted by energetic radiation from the region's young, hot, massive stars, the dark shapes inhabiting the view are clouds of cool gas and dust with stars likely forming within. The North America Nebula itself, NGC 7000, is about 1,500 light-years away. To find it, look northeast of bright star Deneb in the high flying constellation Cygnus.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 4, 2014

What's in the sky tonight?
July 4, 2014

-Out to watch fireworks? As you're waiting for twilight to end, spot the Moon in the west-southwest with Mars and Spica off to its left, as shown for July 4 here. High above them all shines brighter Arcturus. Saturn is farther left.

-Ceres and Vesta at their closest. The two leading asteroids, currently magnitudes 8.5 and 7.2, appear closest together this evening and tomorrow evening, just 10 arcminutes apart. 1 Ceres is the largest asteroid, and 4 Vesta sometimes becomes the brightest.

-Sky watchers in Europe are reporting an outburst of bright noctilucent clouds (NLCs). The display began at sunset on July 3rd, filling northern horizons with electric-blue ripples, swirls, and tendrils of light. Morten Ross sends this picture from Sandbukta, Norway.

"An incredibly bright and widespread display - from northern horizon to zenith!" says Ross. "This is only the third night of July and its already much better than last year." Similar reports have come from France, Germany, Poland, the Netherlands, Scotland, Ireland, England and Belgium.

Although most of the reports so far have come from Europe, the nights ahead could bring NLCs to North America as well.

Astro Picture of the Day:
July 4, 2014

Source:
In this alluring time exposure, star trails arc across the night sky above foggy Monterey Bay and the lights of Santa Cruz, California in the United States of America. Since the exposure began around 2:56am PDT on July 2 it also records the trail of a Delta II rocket lofting NASA's OCO-2 spacecraft into orbit. Seen from a vantage point 200 miles north of the Vandenberg Air Force Base launch site, the trail represents the first five minutes of the rocket's flight along a trajectory south and west over the Pacific to join the A-Train in polar orbit around planet Earth. The entire trail through main engine cut-off is captured, with a very faint puff at the end marking the nose fairing separation. Under the rocket's path, the two brightest trails are the alpha and beta stars of the constellation Grus, flying high in southern skies. The OCO-2 mission goal is a study of atmospheric carbon dioxide, watching from space as planet Earth breathes.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 5, 2014

What's in the sky tonight?
July 5, 2014

-First-quarter Moon. The half-lit Moon is quite close to Mars as seen from North America. The Moon occults (hides) Mars during daylight for Hawaii and at dusk or night in parts of Latin America.

-The two most massive objects in the asteroid belt, dwarf planet Ceres and minor planet Vesta, are converging for a close encounter in the night sky on July 4th and 5th. Last night in Italy, Gianluca Masi used a remotely operated telescope to photograph the monster asteroids only 13 arcminutes apart--less than half the width of a full Moon. The line splitting the two is a terrestrial satellite.

At closest approach on July 5th, the two asteroids will be only 10 arcminutes apart in the constellation Virgo. They are too dim to see with the unaided eye, but easy targets for binoculars and small telescopes. Observing tips are available from Sky and Telescope.

Got clouds? You can watch the close encounter online. Choose between Gianluca Masi's Virtual Telescope Project (which begins July 5th at 4:00 p.m. EDT) or Slooh's webcast (July 3rd at 8 p.m. Eastern Daylight Time).
Virtual Telescope Project: http://www.virtualtelescope.eu/2014/...n-5-july-2014/
Slooh: http://live.slooh.com/

Quite near the two asteroids on the sky, though utterly invisible, is NASA's Dawn spacecraft. Dawn recently finished visiting Vesta and is now en route to Ceres. The ion-propelled spacecraft will enter orbit around Ceres next March. Cameras on Dawn will resolve the pinprick of light you see this weekend into a full-fledged world of unknown wonders. Stay tuned for that!

Astro Picture of the Day:
July 5, 2014

Source:
The spiral arms of bright, active galaxy M106 sprawl through this remarkable multiwavelength portrait, composed of image data from radio to X-rays, across the electromagnetic spectrum. Also known as NGC 4258, M106 can be found toward the northern constellation Canes Venatici. The well-measured distance to M106 is 23.5 million light-years, making this cosmic scene about 60,000 light-years across. Typical in grand spiral galaxies, dark dust lanes, youthful star clusters, and star forming regions trace spiral arms that converge on a bright nucleus. But this composite highlights two anomalous arms in radio (purple) and X-ray (blue) that seem to arise in the central region of M106, evidence of energetic jets of material blasting into the galaxy's disk. The jets are likely powered by matter falling into a massive central black hole.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 6, 2014

What's in the sky tonight?
July 6, 2014

-The Moon this evening poses midway between Saturn at its left and the Mars-Spica pair at its right.

The Moon is very much in the foreground, just 1.3 light-seconds from Earth. Mars is currently 8½ light-minutes away, Saturn is 78 light-minutes away, and Spica is 250 light-years in the background.

-As wide as a World Cup football field, the biggest spacecraft ever built makes a impressive silhouette when it passes in front of the sun. Yesterday, Maximilian Teodorescu of Romania caught the winged shadow of the International Space Station in conjuncton with sunspots AR2104 and AR2107. "This is my first attempt to catch the station with a small-sensor camera at high magnification," he says. "I managed to catch the ISS in three frames."

His wife Eliza was right beside him with her own camera and solar filter, and she caught it too. "The moment was all the more spectacular because the ISS path was almost parallel to the very numerous string of sunspots," she notes. One conjunction after another unfolded as their cameras rolled.

With the sunspot number so high, now is a good time to catch ISS-sunspot conjunctions.

Astro Picture of the Day:
July 6, 2014

Source:
This coming Saturday, if it is clear, well placed New Yorkers can go outside at sunset and watch their city act like a modern version of Stonehenge. Manhattan's streets will flood dramatically with sunlight just as the Sun sets precisely at each street's western end. Usually, the tall buildings that line the gridded streets of New York City's tallest borough will hide the setting Sun. This effect makes Manhattan a type of modern Stonehenge, although only aligned to about 30 degrees east of north. Were Manhattan's road grid perfectly aligned to east and west, today's effect would occur on the Vernal and Autumnal Equinox, March 21 and September 21, the only two days that the Sun rises and sets due east and west. Pictured above in this horizontally stretched image, the Sun sets down 34th Street as viewed from Park Avenue. If Saturday's sunset is hidden by clouds do not despair -- the same thing happens twice each year: in late May and mid July. On none of these occasions, however, should you ever look directly at the Sun.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 7, 2014

What's in the sky tonight?
July 7, 2014

-Now the waxing gibbous Moon shines closely under Saturn in the evening (for North America), as shown at right. For southern South America, the Moon occults Saturn. Timetables: http://www.lunar-occultations.com/io...0708saturn.htm

-Another outbreak of noctilucent clouds is underway over Europe. Jim Henderson sends this picture from Torphins, 15 miles west of Aberdeen, Scotland. "This is the second time this summer we've seen extensive NLCs in Scotland," he says. "I took the picture using a Nikon D700 (f5.6) set at at ISO 500 for 3 seconds."

High-latitude sky watchers, take note of those settings. July is the best month of the year for noctilucent clouds, and your chance to take a similar picture could be just hours away.

Astro Picture of the Day:
July 7, 2014

Source:
Most galaxies contain one supermassive black hole -- why does this galaxy have three? The likely reason is that galaxy J1502+1115 is the product of the recent coalescence of three smaller galaxies. The two closest black holes are shown above resolved in radio waves by large coordinated array of antennas spread out over Europe, Asia, and Africa. These two supermassive black holes imaged are separated by about 500 light years and each has a likely mass about 100 million times the mass of our Sun. Currently, J1502+1115, at a redshift of 0.39, is one of only a few triple black hole system known and is being studied to learn more about galaxy and supermassive black hole interaction rates during the middle ages of our universe. Gravitational radiation emitted by such massive black hole systems may be detectable by future observatories.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 8, 2014

What's in the sky tonight?
July 8, 2014

-The Moon's latest daily shift eastward brings it left of Saturn and upper right of Antares at nightfall. Closer below the Moon are Beta and Delta Scorpii (as seen from North America).

-For the second day in a row, the odds of a powerful flare have increased. NOAA forecasters now estimate a 70% chance of M-flares and a 15% chance of X-flares on July 8th. The likely sources are sunspots AR2108 and AR2109; both have unstable "beta-gamma-delta" magnetic fields that harbor energy for eruptions.

-This morning in Russia, the sunrise was electric-blue. Bright bands of noctilucent clouds zig-zagged like lightning across the twilight sky, continuing a two-day display that has delighted observers across northern Europe. Michael Zavyalov sends this picture taken July 8th from the city of Yaroslavl.

"Another night with bright noctilucent clouds (NLCs) in Yaroslavl!" says Zavyalov. "We could even see their reflection in the water."

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.
In the northern hemisphere, July is the best month to see them. 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, when the upper atmosphere is coldest, allowing the ice crystals of NLCs to form.

The natural habitat of noctilucent clouds is the Arctic Circle. In recent years, however, they have spread to lower latitudes with sightings as far south as Utah and Colorado. This will likely happen in 2014 as well. Observing tips: Look west 30 to 60 minutes after sunset when the Sun has dipped 6o to 16o below the horizon. If you see blue-white tendrils zig-zagging across the sky, you may have spotted a noctilucent cloud.

Astro Picture of the Day:
July 8, 2014

Source:
Why would a cloud appear to be different colors? A relatively rare phenomenon known as iridescent clouds can show unusual colors vividly or a whole spectrum of colors simultaneously. These clouds are formed of small water droplets of nearly uniform size. When the Sun is in the right position and mostly hidden by thick clouds, these thinner clouds significantly diffract sunlight in a nearly coherent manner, with different colors being deflected by different amounts. Therefore, different colors will come to the observer from slightly different directions. Many clouds start with uniform regions that could show iridescence but quickly become too thick, too mixed, or too far from the Sun to exhibit striking colors. The above iridescent cloud was photographed in 2009 from the Himalayan Mountains in Nepal, behind the 6,600-meter peak named Thamserku.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 9, 2014

What's in the sky tonight?
July 9, 2014

-Yesterday, July 8th, Earth-orbiting satellites detected a strong M6-class solar flare. NASA's Solar Dynamics Observatory recorded the extreme ultraviolet flash.

X-ray and UV radiation from the flare sent waves of ionization coursing through Earth's upper atmosphere. This briefly disturbed the propagation of shortwave radio transmissions around the dayside of our planet, especially over Europe and North America. Conditions have since returned to normal.

The flare came as little surprise. A phalanx of large sunspots is crossing the solar disk, and forecasters have been predicting an explosion for more than a week. However, the source of the flare was unexpected. It came from a minor and seemingly harmless sunspot named AR2113. Appearances notwithstanding, AR2113 has a 'beta-gamma' magnetic field that harbors energy for M-class solar flares.

With this flare, AR2113 joins two other sunspots capable of potent activity: AR2108 and AR2109. NOAA forecasters estimate a 75% chance of M-flares and a 20% chance of X-flares on July 9th.

Astro Picture of the Day:
July 9, 2014

Source:
This planet is only 16 light years away -- could it harbor life? Recently discovered exoplanet Gliese 832c has been found in a close orbit around a star that is less bright than our Sun. An interesting coincidence, however, is that Gliese 832c receives just about the same average flux from its parent star as does the Earth. Since the planet was discovered only by a slight wobble in its parent star's motion, the above illustration is just an artistic guess of the planet's appearance -- much remains unknown about Gliese 832c's true mass, size, and atmosphere. If Gliese 832c has an atmosphere like Earth, it may be a super-Earth undergoing strong seasons but capable of supporting life. Alternatively, if Gliese 832c has a thick atmosphere like Venus, it may be a super-Venus and so unlikely to support life as we know it. The close 16-light year distance makes the Gliese 832 planetary system currently the nearest to Earth that could potentially support life. The proximity of the Gliese 832 system therefore lends itself to more detailed future examination and, in the most spectacularly optimistic scenario, actual communication -- were intelligent life found there.



Daily Suspicious0bserver's Weather Post:
July 10, 2014

What's in the sky tonight?
July 10, 2014

-Vega is the brightest star very high in the east these evenings. The brightest to its lower left is Deneb. Farther to Vega's lower right is Altair. These make up the big Summer Triangle.

-Solar activity is low, but the quiet is unlikely to persist. There are three sunspots with unstable magnetic fields capable of strong eruptions: AR2108, AR2109, AR2113. NOAA forecasters estimate a 75% chance of M-flares and 15% chance of X-flares on July 10th.

-After weeks of sightings over Europe, noctilucent clouds (NLCs) are spreading to North America. "A spectacular display emerged over the Edmonton area on July 8/9," reports Canadian photographer Mark Zalcik. "For awhile there were multiple zones of billow-type NLC, including the snake-like one in this photo."

Astro Picture of the Day:
July 10, 2014

Source:
This scene from the early morning hours of July 3 looks out across the River Thames from the Westminster Bridge. Part of a luminous timelapse video (vimeo), the frame captures a sight familiar in London, the nighttime glow of the London Eye. But a not-so-familiar sight is shining in the still dark sky above, widespread noctilucent clouds. From the edge of space, about 80 kilometers above Earth's surface, the icy clouds can still reflect sunlight even though the Sun itself is below the horizon as seen from the ground. Usually spotted at high latitudes in summer months the diaphanous apparitions are also known as polar mesospheric clouds. The seasonal clouds are understood to form as water vapor driven into the cold upper atmosphere condenses on the fine dust particles supplied by disintegrating meteors or volcanic ash. NASA's AIM mission provides daily projections of the noctilucent clouds as seen from space.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 11, 2014

What's in the sky tonight?
July 11, 2014

-Mars and Spica form a striking pair in the southwestern sky at dusk! They're now just under 2° apart. On Sunday evening they'll be at their minimum separation, 1.3°. Watch them change day by day.

-Full Moon tonight and Saturday night (exactly full at 7:25 a.m. Saturday morning Eastern Daylight Time.) This evening the Moon shines in northern Sagittarius. Tomorrow it's in western Capricornus.

Astro Picture of the Day:
July 11, 2014

Source:
In this composite cityscape, dawn's first colors backdrop the lights along Brisbane's skyline at the southeastern corner of Queensland, Australia, planet Earth. Using a solar filter, additional exposures made every 3.5 minutes follow the winter sunrise on July 8 as planet-sized sunspots cross the visible solar disk. The sunspots mark solar active regions with convoluted magnetic fields. Even as the maximum in the solar activity cycle begins to fade, the active regions produce intense solar flares and eruptions launching coronal mass ejections (CMEs), enormous clouds of energetic particles, into our fair solar system.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 12, 2014

What's in the sky tonight?
July 12, 2014

-Look far above the still-full Moon this evening, and a bit left, to spot Altair. Continue a similar distance in roughly the same direction, and there's brighter Vega.

-Earth could receive a glancing blow from a CME on July 13th. It comes from a magnetic filament that erupted from the sun's northern hemisphere on July 9th and hurled part of itself into space. Minor geomagnetic storms are possible when the CME arrives.

-Today's full Moon is a perigee "supermoon," as much as 14% closer and 30% brighter than other full moons of the year. John Stetson photographed the swollen orb setting over Sebago Lake, Maine, this morning just minutes after sunrise. "An inferior mirage appears in the foreground where the lake meets the shoreline," points out Stetson.

This was just the first of three supermooons in a row. Two more are coming on August 10th and September 9th.

-This week, the sun is peppered with big spots. In some places, you can see them even at midnight. "Here in Lofoten islands, north of the Arctic circle, the sun never sets," reports Therese van Nieuwenhoven, "so we can observe sunspots around the clock. "As we enjoyed the beautiful midnight Sun in the north above the sea, my husband was projecting the large sunspots on a white piece of paper," she explains.

Earlier in the week, several of these sunspots posed a threat for strong flares, but now the odds of an explosion are declining. Only one of the decaying active regions (AR2108) still has an unstable 'beta-gamma' magnetic field. NOAA forecasters estimate a waning 60% chance of M-flares on July 12th.

Astro Picture of the Day:
July 12, 2014

Source:
A new star, likely the brightest supernova in recorded human history, lit up planet Earth's sky in the year 1006 AD. The expanding debris cloud from the stellar explosion, found in the southerly constellation of Lupus, still puts on a cosmic light show across the electromagnetic spectrum. In fact, this composite view includes X-ray data in blue from the Chandra Observatory, optical data in yellowish hues, and radio image data in red. Now known as the SN 1006 supernova remnant, the debris cloud appears to be about 60 light-years across and is understood to represent the remains of a white dwarf star. Part of a binary star system, the compact white dwarf gradually captured material from its companion star. The buildup in mass finally triggered a thermonuclear explosion that destroyed the dwarf star. Because the distance to the supernova remnant is about 7,000 light-years, that explosion actually happened 7,000 years before the light reached Earth in 1006. Shockwaves in the remnant accelerate particles to extreme energies and are thought to be a source of the mysterious cosmic rays.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 13, 2014

What's in the sky tonight?
July 13, 2014

-This is the evening when Mars shines closest to Spica. Look southwest at nightfall. They're 1.3° apart. Fiery Mars is the brighter one.

-Last night another outbreak of noctilucent clouds appeared over Europe. Photographer Peter Rosén of Stockholm, Sweden, stitched together 24 exposures taken with a fisheye lens to produce a "Little Planet" projection. "The NLC display last night was just incredible and covered half of the sky with electric blue filaments," says Rosen. "Normaly the Moon would have stolen the show, but a night like this it looked quite lonely on the southern horizon."

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.

In the northern hemisphere, July is the best month to see them. 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, when the upper atmosphere is coldest, allowing the ice crystals of NLCs to form.

The natural habitat of noctilucent clouds is the Arctic Circle. In recent years, however, they have spread to lower latitudes with sightings as far south as Utah and Colorado. This will likely happen in 2014 as well.

Astro Picture of the Day:
July 13, 2014

Source:
NGC 2818 is a beautiful planetary nebula, the gaseous shroud of a dying sun-like star. It could well offer a glimpse of the future that awaits our own Sun after spending another 5 billion years or so steadily using up hydrogen at its core, and then finally helium, as fuel for nuclear fusion. Curiously, NGC 2818 seems to lie within an open star cluster, NGC 2818A, that is some 10,000 light-years distant toward the southern constellation Pyxis (the Compass). At the distance of the star cluster, the nebula would be about 4 light-years across. But accurate velocity measurements show that the nebula's own velocity is very different from the cluster's member stars. The result is strong evidence that NGC 2818 is only by chance found along the line of sight to the star cluster and so may not share the cluster's distance or age. The Hubble image is a composite of exposures through narrow-band filters, presenting emission from nitrogen, hydrogen, and oxygen atoms in the nebula as red, green, and blue hues.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 14, 2014

What's in the sky tonight?
July 14, 2014

-The tail of Scorpius is low in the south after dark — how low depends on how far north you are. Look for the two stars especially close together in the tail. These are Lambda and fainter Upsilon Scorpii, Shaula and Lesath, known as the Cat's Eyes. They're canted at an angle.

-They point west by nearly a fist-width toward Mu Scorpii, a much tighter pair known as the Little Cat's Eyes. Can you resolve Mu without using binoculars?

-All week, Mercury remains almost the same distance to the lower left of bright Venus low in the dawn. The best view may be about 45 minutes before sunrise, depending on how clear the air is.

-The odds of an Earth-directed solar flare are plummeting as sunspots AR2108 and AR2109 rotate over over the sun's western limb. The departure of these two active regions leaves the face of the sun almost blank. Solar activity should remain low for the next 24-48 hours.

Astro Picture of the Day:
July 14, 2014

Source:
Gusting solar winds and blasts of charged particles from the Sun resulted in several rewarding nights last December for those anticipating auroras. The above image captured dramatic auroras stretching across a sky near the town of Yellowknife in northern Canada. The auroras were so bright that they not only inspired awe, but were easily visible on an image exposure of only 1.3 seconds. A video taken concurrently shows the dancing sky lights evolving in real time as tourists, many there just to see auroras, respond with cheers. The conical dwellings on the image right are teepees, while far in the background, near the image center, is the constellation of Orion. Video: http://vimeo.com/85070976

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 15, 2014

What's in the sky tonight?
July 15, 2014

-Vega is the brightest star very high in the east. Far down to its lower right shines Altair, almost as bright. Look left of Altair by about a fist and a half at arm's length, and a little lower, for dim, compact Delphinus, the Dolphin. It's leaping in the lower edge of the Milky Way.

-Frequent fliers who look out the window of their planes often see the shadow of the aircraft dipping in and out of clouds below. The interplay of light and shadow with water droplets in the clouds can produce colorful rings of light called "glories." On July 13th, Tony DeFreece saw a glory that was not a colorful ring, but rather a heart. "I was flying over Oregon when I looked out and saw this heart-shaped figure," he says. "It was one of those moments when the Universe aligns and takes your breath away."

DeFreece suspects, probably correctly, that the shape of the clouds bent the usual circular glory into the heart-shaped apparition. Mystery solved? Not entirely. Glories are caused by sunlight reflected backwards from water droplets in clouds. Exactly how backscattering produces the colorful rings, however, is a mystery involving surface waves and multiple reflections within individual droplets. Each sighting is a lovely puzzle, so grab the window seat and keep an eye on the clouds below.

-NASA's New Horizons spacecraft is only a year away from Pluto. Researchers are buzzing with anticipation as humankind prepares to encounter a new world for the first time in decades.

Astro Picture of the Day:
July 15, 2014

Source:
Why is there a blue bridge of stars across the center of this galaxy cluster? First and foremost the cluster, designated SDSS J1531+3414, contains many large yellow elliptical galaxies. The cluster's center, as pictured above by the Hubble Space Telescope, is surrounded by many unusual, thin, and curving blue filaments that are actually galaxies far in the distance whose images have become magnified and elongated by the gravitational lens effect of the massive cluster. More unusual, however, is a squiggly blue filament near the two large elliptical galaxies at the cluster center. Close inspection of the filament indicates that it is most likely a bridge created by tidal effects between the two merging central elliptical galaxies rather than a background galaxy with an image distorted by gravitational lensing. The knots in the bridge are condensation regions that glow blue from the light of massive young stars. The central cluster region will likely undergo continued study as its uniqueness makes it an interesting laboratory of star formation.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Daily Suspicious0bserver's Weather Post:
July 16, 2014

What's in the sky tonight?
July 16, 2014
[left]-If you have a dark enough sky, the Milky Way now forms a magnificent arch high across the whole eastern sky after nightfall is complete. It runs all the way from below Cassiopeia in the north-northeast, up and across Cygnus and the Summer Triangle in the east, and down past the spout of the Sagittarius Teapot in the south.

-Ten days ago, the sun was peppered with large spots. Now it is nearly blank. This image taken on July 15th by NASA's Solar Dynamics Observatory shows a solar disk almost completely devoid of dark cores.

Long-time readers absorbing this image might be reminded of 2008-2009, years when the sun plunged into the deepest solar minimum in a century. The resemblance, however, is only superficial. Underneath the visible surface of the sun, the solar dynamo is still churning out knots of magnetism that will soon bob to the surface to make sunspots. Solar Max is not finished.

For today, though, it has been paused. Solar activity is low, and NOAA forecasters put the odds of an X-class flare at less than 1%.



Astro Picture of the Day:
July 16, 2014

Source:
What happened to half of Saturn? Nothing other than Earth's Moon getting in the way. As pictured above on the far right, Saturn is partly eclipsed by a dark edge of a Moon itself only partly illuminated by the Sun. This year the orbits of the Moon and Saturn have led to an unusually high number of alignments of the ringed giant behind Earth's largest satellite. Technically termed an occultation, the above image captured one such photogenic juxtaposition from Buenos Aires, Argentina that occurred early last week. Visible to the unaided eye but best viewed with binoculars, there are still four more eclipses of Saturn by our Moon left in 2014. The next one will be on August 4 and visible from Australia, while the one after will occur on August 31 and be visible from western Africa at night but simultaneously from much of eastern North America during the day.