APOD@coRank: Upcoming stories

Stickney Crater

APOD — Sat, 07 Nov 2009 11:18:02 GMT

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 has 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.

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Ring Nebula Deep Field

APOD — Sat, 07 Nov 2009 11:18:02 GMT

A familiar sight to sky enthusiasts with even a small telescope, the Ring Nebula (M57) is some 2,000 light-years away in the musical constellation Lyra . The central ring is about one light-year across, but this remarkably deep exposure - a collaborative effort combining data from three different telescopes - explores the looping filaments of glowing gas extending much farther from the nebula's central star . 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 a dying, sun-like star. This remarkable composite image includes narrowband image data recording the Ring's atomic hydrogen emission (shown as violet) in visible light and molecular hydrogen emission (shown as red) at near infrared wavelengths. The much more distant spiral galaxy IC 1296 is also visible at the upper right.

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Halloween's Moon

APOD — Sat, 07 Nov 2009 11:18:02 GMT

Illuminating the landscape all through the night of November 2nd, this week's bright Full Moon was known in the northern hemisphere as a Hunter's Moon . But this dramatic view of the shining lunar orb, from Sobreda, Portugal, was captured just a few nights earlier, on Halloween . In the spirit of the season , the image plays a little trick. The picture is actually two digital photos - one short and one long exposure. They were combined to bring out the details of the bright lunar surface and the fainter features in the dark, surrounding clouds, in a single image. Of course, you may recognize some of the spookier shapes in the clouds as having visited your neighborhood last week, along with Halloween's Moon .

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Blue Sun Bristling

APOD — Sat, 07 Nov 2009 11:18:02 GMT

Our Sun may look like all soft and fluffy, but it's not. Our Sun is an extremely large ball of bubbling hot gas , mostly hydrogen gas. The above picture of our Sun was taken last month in a specific red color of light emitted by hydrogen gas called Hydrogen-alpha and then color inverted to appear blue. In this light, details of the Sun's chromosphere are particularly visible, highlighting numerous thin tubes of magnetically-confined hot gas known as spicules rising from the Sun like bristles from a shag carpet. Our Sun glows because it is hot, but it is not on fire . Fire is the rapid acquisition of oxygen, and there is very little oxygen on the Sun. The energy source of our Sun is the nuclear fusion of hydrogen into helium deep within its core. No sunspots or large active regions were visible on the Sun this day, although some solar prominences are visible around the edges.

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Seven Sisters Versus California

APOD — Sat, 07 Nov 2009 11:18:02 GMT

On the upper right, dressed in blue, is the Pleiades . Also known as the Seven Sisters and M45 , the Pleiades is one of the brightest and most easily visible open clusters on the sky. The Pleiades contains over 3,000 stars, is about 400 light years away, and only 13 light years across. Surrounding the stars is a spectacular blue reflection nebula made of fine dust . A common legend is that one of the brighter stars faded since the cluster was named. On the lower left, shining in red, is the California Nebula . Named for its shape, the California Nebula is much dimmer and hence harder to see than the Pleiades . Also known as NGC 1499 , this mass of red glowing hydrogen gas is about 1,500 light years away. Although about 250 full moons could fit between them , the above wide angle, deep field image composite has captured them both .

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Ares 1-X Rocket Lifts Off

APOD — Sat, 07 Nov 2009 11:18:02 GMT

Last week, NASA test fired a new rocket. The Ares 1 -X was the first non- shuttle rocket launched from Kennedy Space Center since the Saturn launched humans to Earth orbit and the Moon in the 1960s and 1970s. NASA is testing Ares as a prelude to replacing the aging space shuttle fleet. The tremendous thrust of the Ares 1-X can bring the massive rocket from a standing start to a vertical speed of over 100 kilometers per hour in under eight seconds. The test rocket launched last week was longer than a football field and covered with over 700 sensors to record data that will enable engineers to refine details of future Ares rockets. Pictured above, the Ares 1-X blasts into space while the top part of the rocket becomes engulfed in a shock collar of water droplets likely created by the sudden drop of air pressure.

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The Average Color of the Universe

APOD — Sat, 07 Nov 2009 11:18:02 GMT

What color is the universe? More precisely, if the entire sky was smeared out, what color would the final mix be? This whimsical question came up when trying to determine what stars are commonplace in nearby galaxies. The answer, depicted above , is a conditionally perceived shade of beige . To determine this, astronomers computationally averaged the light emitted by one of the largest sample of galaxies yet analyzed: the 200,000 galaxies of the 2dF survey . The resulting cosmic spectrum has some emission in all parts of the electromagnetic spectrum , but a single perceived composite color. This color has become much less blue over the past 10 billion years, indicating that redder stars are becoming more prevalent. In a contest to better name the color, notable entries included skyvory, univeige, and the winner: cosmic latte .

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VdB 152: Reflection Nebula in Cepheus

APOD — Sat, 07 Nov 2009 11:18:02 GMT

Described as a "dusty curtain" or "ghostly apparition", mysterious reflection nebula VdB 152 really is very faint. Far from your neighborhood on this Halloween Night , the cosmic phantom is nearly 1,400 light-years away. Also cataloged as Ced 201, it lies along the northern Milky Way in the royal constellation Cepheus. Near the edge of a large molecular cloud, pockets of interstellar dust in the region block light from background stars or scatter light from the embedded bright star giving parts of the nebula a characteristic blue color . Ultraviolet light from the star is also thought to cause a dim reddish luminescence in the nebular dust. Though stars do form in molecular clouds , this star seems to have only accidentally wandered into the area, as its measured velocity through space is very different from the cloud's velocity. This deep telescopic image of the region spans about 7 light-years.

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The Bubble and M52

APOD — Sat, 07 Nov 2009 11:18:02 GMT

To the eye, this cosmic composition nicely balances the Bubble Nebula at the upper right with open star cluster M52. 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 (aka 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.

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Zodiacal Light Over Laguna Verde

APOD — Sat, 07 Nov 2009 11:18:02 GMT

An unusual triangle of light is visible this time of year just before dawn, in the northern hemisphere. Once considered a false dawn , this triangle of light is actually Zodiacal Light , light reflected from interplanetary dust particles . The bright reflecting triangle is clearly visible on the right of the above image taken from Laguna Verde near Valpara

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