Poll: Astronomy Picture of the Week for 2011 December 11-17

See new, spectacular, or mysterious sky images.

Please vote for the TWO best APODs (image and text) of December 11-17

Poll ended at Fri Dec 23, 2011 7:27 am

An Unusual Vein of Deposited Rock on Mars
In the Vicinity of the Cone Nebula
A Lunar Eclipse Over an Indian Peace Pagoda
The Umbra of Earth
Red Moon Rising
Comet Lovejoy: Sungrazing Survivor
Total votes: 1098

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Poll: Astronomy Picture of the Week for 2011 December 11-17

Post by owlice » Mon Dec 19, 2011 7:27 am


Please vote for the TWO best Astronomy Pictures of the Day (image and text) of December 4-10, 2011.
(Repeated APODs are not included in the poll.)

All titles are clickable and link to the original APOD page.

We ask for your help in choosing an APOW as this helps Jerry and Robert create "year in APOD images" review lectures, create APOM and APOY polls that can be used to create a free PDF calendar at year's end, and provides feedback on which images and APODs were relatively well received. You can select two top images for the week.

We are very interested in why you selected the APODs you voted for, and enthusiastically welcome your telling us why by responding to this thread.

Thank you!

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What could create this unusual vein of rock on Mars? A leading hypothesis is that this thin rock layer dubbed "Homestake" was deposited by a running liquid -- like most mineral veins are here on Earth. And the running liquid of choice is water. Therefore, this mineral streak -- rich in calcium and sulfur -- is the latest in the growing body of evidence that part of Mars had a watery past. This, in turn, increases the speculation that Mars was once hospitable to life. Pictured above is a vista taken near the western rim of Endeavour Crater by the Opportunity rover currently exploring Mars. The inset image shows a close up of the recently discovered mineral vein.

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). The origin of the mysterious geometric Cone Nebula, visible on the far left, remains a mystery.

Our Moon turned red last week. The reason was that during December 10, a total lunar eclipse occurred. The above digitally superimposed image mosaic captured the Moon many times during the eclipse, from before the Moon entered Earth's shadow until after the Moon exited. The image sequence was recorded over a Shanti Stupa Peace Pagota near the center of New Delhi, India. The red tint of the eclipsed Moon was created by sunlight first passing through the Earth's atmosphere, which preferentially scatters blue light (making the sky blue) but passes and refracts red light, before reflecting back off the Moon. Differing amounts of clouds and volcanic dust in the Earth's atmosphere make each lunar eclipse appear differently. The next total lunar eclipse will occur only in 2014.

The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, it has a circular cross section most easily seen during a lunar eclipse. For example, last Saturday the Full Moon slid across the southern half of Earth's umbral shadow, entertaining moonwatchers around much of the planet. In the total phase of the eclipse, the Moon was completely within the umbra for 51 minutes. Recorded from Beijing, China, this composite eclipse image uses successive pictures from totality (center) and partial phases to trace out a large part of the umbra's curved edge. Background stars are visible in the darker eclipse phases. The result shows the relative size of the shadow's cross section at the distance of the Moon, as well as the Moon's path through Earth's umbra.

This surreal, wintry scene is a composite picture recorded on December 10 as the Moon rose behind the Zagros Mountains of Iran. A total lunar eclipse was already in progress. The image combines nearly 500 successive frames taken over 1.5 hours beginning in twilight as the eclipsed Moon steadily climbed above the rugged landscape. The reddened lunar disk and deep blue twilight make for a striking contrast, yet the contrasting colors have the same root cause. The eclipsed Moon is red because the Earth's umbral shadow is suffused with a faint red light. The ruddy illumination is from all the reddened sunsets and sunrises, as seen from a lunar perspective. But the sunsets and sunrises are reddened because the Earth's atmosphere scatters blue light more strongly than red, creating the twilight sky's dim, blue glow.

Like most other sungrazing comets, Comet Lovejoy (C/2011 W3) was not expected to survive its close encounter with the Sun. But it did. This image from a coronograph onboard the sun-staring SOHO spacecraft identifies the still inbound remnants of the tail, with the brilliant head or coma emerging from the solar glare on December 16. The Sun's position, behind an occulting disk to block the overwhelming glare, is indicated by the white circle. Separated from its tail, Comet Lovejoy's coma is so bright it saturates the camera's pixels creating the horizontal streaks. Based on their orbits, sungrazer comets are thought to belong to the Kreutz family of comets, created by successive break ups from a single large parent comet that passed very near the Sun in the twelfth century. Most have been discovered with SOHO's cameras, but unlike many sungrazers, this one was first spotted by Australian astronomer Terry Lovejoy from an earth-based observatory. Comet Lovejoy is estimated to have come within 120,000 kilometers of the Sun's surface and likely had a large cometary nucleus to have survived its intense perihelion passage. Remarkable videos of the encounter from the Solar Dynamics Observatory can be found here.

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A closed mouth gathers no foot.


Re: Poll: Astronomy Picture of the Week for 2011 December 11

Post by Feagles » Tue Dec 20, 2011 2:47 pm

The umbral picture is cleverly composed to help see the celestial mechanics involved in an off center pass.
The sungrazing comet helps me see both the remarkable advances and the limits of the current technology.


Re: Poll: Astronomy Picture of the Week for 2011 December 11

Post by Stepo » Tue Dec 20, 2011 3:47 pm

Re: Lunar...Peace Pagoda: I love India, I love beautiful architecture, I love Peace and I love the Moon. :ssmile:
Re: Comet Lovejoy: I chanced to share the link with some friends with whom I hope to stay in touch and they were favorably impressed. 8-)


Re: Poll: Astronomy Picture of the Week for 2011 December 11

Post by apod_viewer_116 » Tue Dec 20, 2011 4:12 pm

"umbral" appeals because it acts as a visualisation aid in understanding the size relationship between the moon and the earth, in a way that would not be possible simply by looking up at the sky. in this way it is both beautiful and a teacher, the two reasons i visit apod regularly.

"lovejoy" for similar reasons, although the beauty is less visual and more cerebral: that we're able to watch as a (comparatively) tiny bit of dirty ice hurtles 1,000 times closer to the sun than is the earth, experiencing (likely over) 1 million time the incident and radiation solar heating... is unprecedented... and beautiful.


Re: Poll: Astronomy Picture of the Week for 2011 December 11

Post by anderqn@aol.com » Tue Dec 20, 2011 5:35 pm

I chose UMBRA of EARTH - - it was fascinating and new for me to see it. Seemed quite original in its photographic method, too.

Also chose COMET enroute to and from our Sun - - text was excellent teaching material. Entire aspect of seeing this celestial event was much appreciated.