Poll: Astronomy Picture of the Month for 2011 November

See new, spectacular, or mysterious sky images.

Please select TWO (2) choices for the Astronomy Picture of the Month for November 2011

Poll ended at Sat Dec 17, 2011 8:57 am

Hammer Versus Feather on the Moon
Edge-on NGC 3628
Star Forming Region S106
In the Arms of M83
Sunspot Castle
Waterfall, Moonbow, and Aurora from Iceland
Around the World in 90 Minutes
A Landslide on Asteroid Vesta
Across the Center of Centaurus A
Total votes: 163

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Poll: Astronomy Picture of the Month for 2011 November

Post by owlice » Mon Dec 12, 2011 8:57 am


Please vote for the two best APODs (image and text) for November, 2011. All titles are clickable and link to the original APOD page.

We ask for your help in choosing an APOM, as this helps Jerry and Robert create "year in APOD images" review lectures and a free PDF calendar at year's end, and provides feedback on which images and APODs were relatively well received.

We are very interested to know why you selected the APODs for which you voted; if you would like to tell us, please reply to this thread. Thank you!

Thank you!

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Click to play embedded YouTube video.
Image Credit: Apollo 15 Crew, NASA
If you drop a hammer and a feather together, which reaches the ground first? On the Earth, it's the hammer, but is the reason only because of air resistance? Scientists even before Galileo have pondered and tested this simple experiment and felt that without air resistance, all objects would fall the same way. Galileo tested this principle himself and noted that two heavy balls of different masses reached the ground simultaneously, although many historians are skeptical that he did this experiment from Italy's Leaning Tower of Pisa as folklore suggests. A good place free of air resistance to test this equivalence principle is Earth's Moon, and so in 1971, Apollo 15 astronaut David Scott dropped both a hammer and a feather together toward the surface of the Moon. Sure enough, just as scientists including Galileo and Einstein would have predicted, they reached the lunar surface at the same time. The demonstrated equivalence principle states that the acceleration an object feels due to gravity does not depend on its mass, density, composition, color, shape, or anything else. The equivalence principle is so important to modern physics that its depth and reach are still being debated and tested even today.

Sharp telescopic views of magnificent edge-on spiral galaxy NGC 3628 show a puffy galactic disk divided by dark dust lanes. The tantalizing scene puts many astronomers in mind of its popular moniker, The Hamburger Galaxy. About 100,000 light-years across and 35 million light-years away in the constellation Leo, NGC 3628 shares its neighborhood in the local Universe with two other large spirals, a grouping otherwise known as the Leo Triplet. Gravitational interactions with its cosmic neighbors are likely responsible for the extended flare and warp of this spiral's disk, populated by the galaxy's young blue star clusters and tell tale pinkish star forming regions. Also a result of past close encounters, a faint tidal tail of material is just visible extending upward and left in this deep galaxy portrait.

Massive star IRS 4 is beginning to spread its wings. Born only about 100,000 years ago, material streaming out from this newborn star has formed the nebula dubbed Sharpless 2-106 Nebula (S106), pictured above. A large disk of dust and gas orbiting Infrared Source 4 (IRS 4), visible in dark red near the image center, gives the nebula an hourglass or butterfly shape. S106 gas near IRS 4 acts as an emission nebula as it emits light after being ionized, while dust far from IRS 4 reflects light from the central star and so acts as a reflection nebula. Detailed inspection of images like the above image has revealed hundreds of low-mass brown dwarf stars lurking in the nebula's gas. S106 spans about 2 light-years and lies about 2000 light-years away toward the constellation of the Swan (Cygnus).

Big, bright, and beautiful, spiral galaxy M83 lies a mere twelve million light-years away, near the southeastern tip of the very long constellation Hydra. This cosmic close-up, a mosaic based on data from the Hubble Legacy Archive, traces dark dust and young, blue star clusters along prominent spiral arms that lend M83 its nickname, The Southern Pinwheel. Typically found near the edges of the thick dust lanes, a wealth of reddish star forming regions also suggest another popular moniker for M83, The Thousand-Ruby Galaxy. Dominated by light from older stars, the bright yellowish core of M83 lies at the upper right. The core is also bright at x-ray energies that reveal a high concentration of neutron stars and black holes left from an intense burst of star formation. In fact, M83 is a member of a group of galaxies that includes active galaxy Centaurus A. The close-up field of view spans over 25,000 light-years at the estimated distance of M83.

Each day can have a beautiful ending as the Sun sets below the western horizon. This week, the setting Sun added naked-eye sunspots to its finale, as enormous active regions rotated across the dimmed, reddened solar disc. Near the Sun's center in this closing telephoto view from November 7th are sunspots in Active Region 1339. Responsible for a powerful X-class flare on November 3rd, Active Region 1339 is larger than Jupiter. In the foreground, the ruined tower of a medieval castle stands in dramatic silhouette. Located in Igersheim, Germany and traditionally known as castle Neuhaus, it might be named Sunspot Castle for this well-composed scene.

The longer you look at this image, the more you see. Perhaps your eye is first drawn to the picturesque waterfall called Skogarfoss visible on the image right. Just as prevalent, however, in this Icelandic visual extravaganza, is the colorful arc of light on the left. This chromatic bow is not a rainbow, since the water drops did not originate in rainfall nor are they reflecting light from the Sun. Rather, the drops have drifted off from the waterfall and are now illuminated by the nearly full Moon. High above are the faint green streaks of aurora. The scene, captured one night last month, also shows a beautiful starscape far in the background, including the Big Dipper, part of the constellation of the Great Bear (Ursa Major).

Video Credit: Expedition 28 & 29 Crews, ISAL, NASA's JSC;
Compilation and Editing: Michael König; Music: Do Dekor (Jan Jelinek), faitiche
What is it like to circle the Earth? Every 90 minutes, astronauts aboard the International Space Station experience just that. Recently, crew members took a series of light-sensitive videos looking down at night that have been digitally fused to produce the above time-lapse video. Many wonders of the land and sky are visible in the eighteen sequences, including red aurora above green aurora, lights from many major cities, and stars in the background. Looming at the top of the frame is usually part of the space station itself, sometimes seen re-orienting solar panels. Please help create a useful companion guide for this moving video by identifying landmarks, cities, countries, weather phenomena, and even background constellations that appear.

Asteroid Vesta is home to some of the most impressive cliffs in the Solar System. Pictured above near the image center is a very deep cliff running about 20 kilometers from top to bottom. The image was taken by the robotic Dawn spacecraft that began orbiting the 500-kilometer space rock earlier this year. The topography of the scarp and its surroundings indicates that huge landslides may have occurred down this slope. The scarp's origin remains unknown, but parts of the cliff face itself must be quite old as several craters have appeared in it since it was created. Dawn has now finished up its high altitude mapping survey and will spiral down to a lower altitude orbit to better explore the asteroid's gravitational field. During 2012, Dawn is scheduled to blast away from Vesta and begin a long journey to the only asteroid belt object known to be larger: Ceres.

A fantastic jumble of young blue star clusters, gigantic glowing gas clouds, and imposing dark dust lanes surrounds the central region of the active galaxy Centaurus A. This image from the Hubble Space Telescope has been processed to present a natural color picture of this cosmic maelstrom. Infrared images from the Hubble have also shown that hidden at the center of this activity are what seem to be disks of matter spiraling into a black hole with a billion times the mass of the Sun. Centaurus A itself is apparently the result of a collision of two galaxies and the left over debris is steadily being consumed by the black hole. Astronomers believe that such black hole central engines generate the radio, X-ray, and gamma-ray energy radiated by Centaurus A and other active galaxies. But for an active galaxy Centaurus A is close, a mere 10 million light-years away, and is a relatively convenient laboratory for exploring these powerful sources of energy.

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