Terry's Astronomy Thread.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 16, 2013

-Venus (magnitude –3.9) is getting lower in the dawn each morning. Look for it above the southeast horizon about 30 minutes before your local sunrise.

-Mars (magnitude +1.2, in Sagittarius) still glimmers very low in the west-southwest in the fading glow of sunset. Don't confuse it with Fomalhaut far to its left.

Astro Picture of the Day:
January 16, 2013

Source:
A gorgeous spiral galaxy some 100 million light-years distant, NGC 1309 lies on the banks of the constellation of the River (Eridanus). NGC 1309 spans about 30,000 light-years, making it about one third the size of our larger Milky Way galaxy. Bluish clusters of young stars and dust lanes are seen to trace out NGC 1309's spiral arms as they wind around an older yellowish star population at its core. Not just another pretty face-on spiral galaxy, observations of NGC 1309's recent supernova and Cepheid variable stars contribute to the calibration of the expansion of the Universe. Still, after you get over this beautiful galaxy's grand design, check out the array of more distant background galaxies also recorded in the above, sharp, reprocessed, Hubble Space Telescope view.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 17, 2013

-Bright Capella high overhead and bright Rigel in Orion's foot, both magnitude 0, have almost the same right ascension — so they transit your north-south meridian at the almost same time. Capella passes closest to the zenith around 9 or 10 p.m. this week, depending on how far east or west you live in your time zone. (It goes exactly through the zenith if you're at latitude 46° north: Portland, Oregon; Montreal; central France.) So, whenever Capella is closest to the zenith, Rigel always marks true south over your landscape.

News Posted Today:
January 16, 2013
Galactic Bubbles Spark Debate


Astro Picture of the Day:
January 17, 2013

Source:
The aftermath of a cosmic cataclysm, supernova remnant Cassiopeia A (Cas A) is a comfortable 11,000 light-years away. Light from the Cas A supernova, the death explosion of a massive star, first reached Earth just 330 years ago. Still expanding, the explosion's debris cloud spans about 15 light-years near the center of this composite image. The scene combines color data of the starry field and fainter filaments of material at optical energies with image data from the orbiting NuSTAR X-ray telescope. Mapped to false colors, the X-ray data in blue hues trace the fragmented outer ring of the expanding shock wave, glowing at energies up to 10,000 times the energy of the optical photons.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 18, 2013

-First-quarter Moon. The Moon is exactly half lit at 6:45 p.m. EST. In early evening, look above the Moon by about about a fist-width at arm's length for the brightest two or three stars of Aries. These are aligned more or less vertically.

Astro Picture of the Day:
January 18, 2013

Source:
Stickney Crater, the largest crater on the martian moon Phobos, is named for Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the Red Planet's moons in 1877. Over 9 kilometers across, Stickney is nearly half the diameter of Phobos itself, so large that the impact that blasted out the crater likely came close to shattering the tiny moon. This stunning, enhanced-color image of Stickney and surroundings was recorded by the HiRISE camera onboard the Mars Reconnaissance Orbiter as it passed within some six thousand kilometers of Phobos in March of 2008. Even though the surface gravity of asteroid-like Phobos is less than 1/1000th Earth's gravity, streaks suggest loose material slid down inside the crater walls over time. Light bluish regions near the crater's rim could indicate a relatively freshly exposed surface. The origin of the curious grooves along the surface is mysterious but may be related to the crater-forming impact.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 19, 2013

-In twilight, bright Jupiter comes into view well to the lower left of the Moon. By 8 p.m. things have turned around and Jupiter is shining to the Moon's left or upper left. Closer to the Moon's lower left is the big, dim head of Cetus with its one 2nd-magnitude star, orange Alpha Ceti (Menkar).

-Venus (magnitude –3.9) is just above the southeast horizon about 30 minutes before your local sunrise. It's lower each morning. How much longer can you keep it in view?

Astro Picture of the Day:
January 19, 2013

Source:
A gaze across a cosmic skyscape, this telescopic mosaic reveals the continuous beauty of things that are. The evocative scene spans some 6 degrees or 12 Full Moons in planet Earth's sky. At the left, folds of red, glowing gas are a small part of an immense, 300 light-year wide arc. Known as Barnard's loop, the structure is too faint to be seen with the eye, shaped by long gone supernova explosions and the winds from massive stars, and still traced by the light of hydrogen atoms. Barnard's loop lies about 1,500 light-years away roughly centered on the Great Orion Nebula, a stellar nursery along the edge of Orion's molecular clouds. But beyond lie other fertile star fields in the plane of our Milky Way Galaxy. At the right, the long-exposure composite finds NGC 2170, a dusty complex of nebulae near a neighboring molecular cloud some 2,400 light-years distant.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 20, 2013

-The naked-eye eclipsing variable star Algol is at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours tonight centered on 12:48 a.m. EST (9:48 p.m. PST.) It takes several additional hours to fade and to rebrighten.

-The waxing gibbous Moon highlights an interesting section of the winter sky. (The Moon symbols are positioned for the middle of North America. They are drawn three times the Moon's actual apparent size.)

News Posted Today:
January 18, 2013
Mapping the Milky Way


Astro Picture of the Day:
January 20, 2013

Source:
Gazing out from within the Milky Way, our own galaxy's true structure is difficult to discern. But an ambitious survey effort with the Spitzer Space Telescope now offers convincing evidence that we live in a large galaxy distinguished by two main spiral arms (the Scutum-Centaurus and Perseus arms) emerging from the ends of a large central bar. In fact, from a vantage point that viewed our galaxy face-on, astronomers in distant galaxies would likely see the Milky Way as a two-armed barred spiral similar to this artist's illustration. Previous investigations have identified a smaller central barred structure and four spiral arms. Astronomers still place the Sun about a third of the way in from the Milky Way's outer edge, in a minor arm called the Orion Spur.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 21, 2013

-Close conjunction of the Moon and Jupiter. Look for a bright "star" unusually near the waxing gibbous Moon this evening, as shown above. The Moon passes less than 1° from it for most of the U.S. and Canada. This is an opportunity where you can try to find Jupiter before the sun sets. It is the faint dot beside the moon at sunset! Think photo opportunity; use a long lens, or zoom to the max. In much of South America the Moon actually occults (covers) Jupiter; To find out where you can see the occultation, go here: http://www.lunar-occultations.com/io...122jupiter.htm

-Although they look close together, the Moon is only 1.3 light-seconds distant from Earth, while Jupiter is 1,700 times farther away at a distance of 37 light-minutes.

Astro Picture of the Day:
January 21, 2013

Source:
What is it? It was found at the bottom of the sea aboard an ancient Greek ship. Its seeming complexity has prompted decades of study, although some of its functions remained unknown. X-ray images of the device have confirmed the nature of the Antikythera mechanism, and discovered several surprising functions. The Antikythera mechanism has been discovered to be a mechanical computer of an accuracy thought impossible in 80 BC, when the ship that carried it sank. Such sophisticated technology was not thought to be developed by humanity for another 1,000 years. Its wheels and gears create a portable orrery of the sky that predicted star and planet locations as well as lunar and solar eclipses. The Antikythera mechanism, shown above, is 33 centimeters high and therefore similar in size to a large book.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 22, 2013

-By now the Moon has moved eastward from Jupiter along its orbit to shine well to Jupiter's left after dinnertime, as shown above.

-Look below the Moon for Orion, and far below Orion for brilliant Sirius.

Astro Picture of the Day:
January 22, 2013

Source:
The North America nebula on the sky can do what the North America continent on Earth cannot - form stars. Specifically, in analogy to the Earth-confined continent, the bright part that appears as Central America and Mexico is actually a hot bed of gas, dust, and newly formed stars known as the Cygnus Wall. The above image shows the star forming wall lit and eroded by bright young stars, and partly hidden by the dark dust they have created. The part of the North America nebula (NGC 7000) shown spans about 15 light years and lies about 1,500 light years away toward the constellation of the Swan (Cygnus).

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 23, 2013

-Week by week, watch the Big Dipper rearing higher up in the northeast as we leave more of winter behind us.

-Two of Jupiter's moons emerge out of eclipse by Jupiter's shadow tonight: Europa at 7:05 p.m. EST, and Io at 12:16 a.m. EST. With a telescope, watch both swell into view off Jupiter's eastern limb. Meanwhile, Jupiter's Great Red Spot rotates across the planet's centerline around 11:27 p.m. EST.

-Algol is at its minimum brightness for a couple hours centered on 9:37 p.m. EST.

Astro Picture of the Day:
January 23, 2013

Source:
Large spiral galaxy NGC 4945 is seen edge-on near the center of this cosmic galaxy portrait. In fact, NGC 4945 is almost the size of our own Milky Way Galaxy. Its own dusty disk, young blue star clusters, and pink star forming regions standout in the sharp, colorful telescopic image. About 13 million light-years distant toward the expansive southern constellation Centaurus, NGC 4945 is only about six times farther away than Andromeda, the nearest large spiral galaxy to the Milky Way. Though the galaxy's central region is largely hidden from view for optical telescopes, X-ray and infrared observations indicate significant high energy emission and star formation in the core of NGC 4945. Its obscured but active nucleus qualifies the gorgeous island universe as a Seyfert galaxy and likely home to a central supermassive black hole.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 24, 2013

-The bright Moon shines about midway between Betelgeuse in Orion's shoulder to its right, and Pollux in Gemini to the Moon's left. The star above Pollux is Castor. Below the Moon is Procyon in Canis Minor.

-Mars (magnitude +1.2) still glimmers very low in the west-southwest in the fading glow of sunset. Don't confuse it with Fomalhaut far to its left. (On January 24th Mars is at perihelion, its closest to the Sun in its orbit.)

-Venus (magnitude –3.9) is just above the southeast horizon about 30 minutes before your local sunrise. It's lower each morning. How much longer can you keep it in view?

Astro Picture of the Day:
January 24, 2013

Source:
Clouds on a summer night frame this sea and skyscape, recorded earlier this month near Buenos Aires, Argentina. But planet Earth's clouds are not the only clouds on the scene. Starry clouds and nebulae along the southern hemisphere's summer Milky Way arc above the horizon, including the dark Coal Sack near the Southern Cross and the tantalizing pinkish glow of the Carina Nebula. Both the Large (top center) and Small Magellanic Clouds are also in view, small galaxies in their own right and satellites of the Milky Way up to 200,000 light-years distant. Alpha star of the Carina constellation and second brightest star in Earth's night, Canopus shines above about 300 light-years away. Still glinting in sunlight at an altitude of 400 kilometers, the orbiting International Space Station traces a long streak through the single, 5 minute, star-tracking exposure.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 25, 2013

-This evening the Moon shines not quite midway between Procyon to its lower right and Pollux to its upper left.

-Around 10 p.m. this week (depending on how far east or west you live in your time zone), brilliant Sirius is at its highest due south.

-Sirius is the brightest star in the night sky — and are you far enough south to see the second brightest, Canopus? In one of the many interesting coincidences that devoted skywatchers know about, Canopus lies almost due south of Sirius: by 36°. That's far enough south that it never appears above your horizon unless you're below latitude 37° N (southern Virginia, southern Missouri, central California). And there, you'll need a flat south horizon. Canopus transits the sky's north-south meridian just 21 minutes before Sirius does.

-When to look? Canopus is at its highest point when Beta Canis Majoris — Mirzim, the star a few finger-widths to the right of Sirius — is at its highest point crossing the meridian. Look straight down from Mirzim then.

News Posted Today:
January 24, 2013
Pulsar Twitches Leave Astronomers Perplexed


Astro Picture of the Day:
January 25, 2013

Source:
On January 25 (UT) 2004, the Opportunity rover fell to Mars, making today the 9th anniversary of its landing. After more than 3,200 sols (Mars solar days) the golf cart-sized robot from Earth is still actively exploring the Red Planet, though its original mission plan was for three months. Having driven some 35 kilometers (22 miles) from its landing site, Opportunity's panoramic camera recorded the segments of this scene, in November and December of last year. The digitally stitched panorama spans more than 210 degrees across the Matijevic Hill area along the western rim of Endeavour Crater. Features dubbed Copper Cliff, a dark outcrop, appear at the left, and Whitewater Lake, a bright outcrop, at the far right. The image is presented here in a natural color approximation of what the scene would look like to human eyes.

[YoshL]

Re: Terry's Astronomy Thread.

mfw these pictures get shown in astronomy

and you (or the site, idk) do a better job of explaining

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 26, 2013

-Full Moon (exact at 11:38 p.m. EST). The Moon is in dim Cancer, with Procyon shining off to its right or upper right during evening, and Pollux and Castor above it.

-Algol in Perseus is at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 6:26 p.m. EST. Watch it gradually rebrighten though the evening.

Astro Picture of the Day:
January 26, 2013

Source:
Moonlight illuminates a snowy scene in this night land and skyscape made on January 17 from Lower Miller Creek, Alaska, USA. Overexposed near the mountainous western horizon is the first quarter Moon itself, surrounded by an icy halo and flanked left and right by moondogs. Sometimes called mock moons, a more scientific name for the luminous apparations is paraselenae (plural). Analogous to a sundog or parhelion, a paraselene is produced by moonlight refracted through thin, hexagonal, plate-shaped ice crystals in high cirrus clouds. As determined by the crystal geometry, paraselenae are seen at an angle of 22 degrees or more from the Moon. Compared to the bright lunar disk, paraselenae are faint and easier to spot when the Moon is low.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 27, 2013

-The Moon shines high in the east by 9 p.m. Lower left of it, by roughly a fist-width at arm's length, sparkles Regulus in Leo, as shown below. The Sickle of Leo extends upper left from Regulus. The emergence of Leo in the evening sky is always an early sign that spring is eventually coming.

-Venus (magnitude –3.9) is just above the southeast horizon 20 minutes before your local sunrise. It's getting lower each morning. Bring binoculars.

Astro Picture of the Day:
January 27, 2013

Source:
Comet McNaught of 2007 has been, so far, the most photogenic comet of our time. After making quite a show in the northern hemisphere in early 2007 January, the comet moved south and developed a long and unusual dust tail that dazzled southern hemisphere observers. In this image, Comet McNaught was captured above Santiago, Chile. The bright comet dominates on the left while part of its magnificent tail spreads across the entire frame. From this vantage point in the Andes Mountains, one looks up toward Comet McNaught and a magnificent sky, across at a crescent moon, and down on clouds, atmospheric haze, and the city lights. The current year 2013 holds promise to be even better for comets than 2007. In early March, Comet PANSTARRS is on track to become visible to the unaided eye, while at the end of the year Comet ISON shows possibilities that include casting a tail that spreads across the sky, breaking up, and even becoming one of the brightest comets in recorded history.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 28, 2013

-Once the waning gibbous Moon is well up in the east in mid- to late evening, look upper left of it for Regulus with the Sickle of Leo extending beyond, as shown here. Look about twice as far to the Moon's right for Alphard, the fire-colored heart of Hydra.

-Jupiter (magnitude –2.5, in Taurus) is the first "star" to come out high in the southeast after sundown. It dominates the high south after dinnertime, with orange Aldebaran lower left or left of it, and the Pleiades to its upper right or right.

-For many weeks, Jupiter has been drawing closer to forming a straight line with Aldebaran and Pleiades. It'll never get there. Jupiter reaches its stationary point on January 30th, when it ceases its retrograde (westward) motion against the stars and starts moving back eastward.

-In a telescope, Jupiter has been slowly shrinking as Earth pulls ahead of it in our faster orbit around the Sun. It appears about 44 arcseconds wide. The 5th-magnitude star 0.1° south of it this week is Omega-2 Tauri.

Astro Picture of the Day:
January 28, 2013

Source:
Clouds of glowing gas mingle with dust lanes in the Trifid Nebula, a star forming region toward the constellation of the Archer (Sagittarius). In the center, the three prominent dust lanes that give the Trifid its name all come together. Mountains of opaque dust appear on the right, while other dark filaments of dust are visible threaded throughout the nebula. A single massive star visible near the center causes much of the Trifid's glow. The Trifid, also known as M20, is only about 300,000 years old, making it among the youngest emission nebulae known. The nebula lies about 9,000 light years away and the part pictured here spans about 10 light years. The above image is a composite with luminance taken from an image by the 8.2-m ground-based Subaru Telescope, detail provided by the 2.4-m orbiting Hubble Space Telescope, color data provided by Martin Pugh and image assembly and processing provided by Robert Gendler.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
January 29, 2013

-Around 9 or 10 p.m. this week (depending on how far east or west you live in your time zone), brilliant Sirius is at its highest due south.

-Mars (magnitude +1.2) still glimmers very low in the west-southwest in the fading glow of sunset. Don't confuse it with Fomalhaut well to its left.

Astro Picture of the Day:
January 29, 2013

Source:
What would it be like to drive on the Moon? You don't have to guess - humans have actually done it. Pictured above, Apollo 16 astronauts John Young and Charles Duke recorded video during one such drive in 1972, with a digital version now available on the web. No matter which direction it headed, the Lunar Rover traveled a path literally covered with rocks and craters. The first half of the above video shows the rover zipping about a moonscape near 10 kilometers per hour, while the second half shows a dash-cam like view. The Lunar Rover was deployed on the later Apollo missions as a way for astronauts to reach and explore terrain further from the Lunar Module basecamp than was possible by walking in cumbersome spacesuits. Possible future lunar missions that might deploy robotic rovers capable of beaming back similar videos include those by China, Russia, India, and Google X-Prize contestants.