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!
_____________________________________________________________________
<- Previous month's poll
Click to play embedded YouTube video.
Image Credit: Apollo 15 Crew, NASAIf 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.
<- Previous month's poll
[size=200][color=#FF0000]_____________________________________________________________________[/color][/size]
Please vote for the [b]two[/b] 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!
[size=200][color=#FF0000]_____________________________________________________________________[/color][/size]
[size=110][url=http://asterisk.apod.com/viewtopic.php?f=29&t=25873][color=#4040FF][b]<- Previous month's poll[/b][/color][/url][/size]
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[c][url=http://apod.nasa.gov/apod/ap111101.html][size=150][b]Hammer Versus Feather on the Moon (2011 Nov 01)[/b][/size][/url][/c]
[float=left][youtube6]http://www.youtube.com/watch?v=4mTsrRZEMwA[/youtube6]
[size=85]Image Credit: Apollo 15 Crew, NASA[/size][/float]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 [url=http://www.youtube.com/watch?v=akWo3QpiL2I]air resistance?[/url] Scientists even before [url=http://www.pbs.org/wgbh/nova/physics/galileo-experiments.html]Galileo[/url] have [url=http://www.swapmeetdave.com/Humor/Cats/Curious.jpg]pondered[/url] and tested this simple experiment and felt that without air resistance, all objects would fall the same way. [url=http://galileo.rice.edu/gal/intro.html]Galileo[/url] 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 [url=http://en.wikipedia.org/wiki/Italy]Italy[/url]'s [url=http://en.wikipedia.org/wiki/Leaning_Tower_of_Pisa]Leaning Tower of Pisa[/url] as folklore suggests. A good place free of air resistance to test this equivalence principle is [url=http://apod.nasa.gov/apod/ap051113.html]Earth's Moon[/url], and so in 1971, [url=http://www.nasm.si.edu/collections/imagery/apollo/AS15/a15sum.htm]Apollo 15[/url] astronaut [url=http://en.wikipedia.org/wiki/David_Scott]David Scott[/url] dropped both a [url=http://www.hq.nasa.gov/alsj/a15/video15.html]hammer and a feather together[/url] toward the surface of the Moon. Sure enough, just as scientists including Galileo and [url=http://apod.nasa.gov/apod/ap000108.html]Einstein[/url] would have predicted, they reached the [url=http://www.hq.nasa.gov/alsj/]lunar surface[/url] at the same time. The demonstrated [url=http://en.wikipedia.org/wiki/Equivalence_principle]equivalence principle[/url] states that the acceleration an object feels due to gravity does not depend on its mass, density, composition, color, shape, or anything else. The [url=http://science.nasa.gov/science-news/science-at-nasa/2007/18may_equivalenceprinciple/]equivalence principle[/url] is so important to [url=http://asterisk.apod.com/viewforum.php?f=39]modern physics[/url] that its depth and reach are still being [url=http://adsabs.harvard.edu/abs/1968PhRv..169.1014N]debated[/url] and [url=http://www.sstd.rl.ac.uk/fundphys/step/]tested[/url] even today.
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[c][url=http://apod.nasa.gov/apod/ap111104.html][size=150][b]Edge-on NGC 3628 (2011 Nov 04)[/b][/size][/url][/c]
[float=left][img6="Image Credit & Copyright: Stephen Leshin"]http://apod.nasa.gov/apod/image/1111/NGC3628_LRGBleshin900c.jpg[/img6][hr][/hr][/float]Sharp telescopic views of magnificent edge-on spiral [url=http://messier.seds.org/xtra/ngc/n3628.html]galaxy NGC 3628[/url] show a puffy [url=http://apod.nasa.gov/apod/ap090613.html]galactic disk[/url] divided by dark dust lanes. The tantalizing scene puts many astronomers [url=http://apod.nasa.gov/apod/ap020807.html]in mind[/url] 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 [url=http://www.atlasoftheuniverse.com/galgrps/leoi.html]local Universe[/url] with two other large spirals, a grouping otherwise known as [url=http://apod.nasa.gov/apod/ap110803.html]the Leo Triplet[/url]. 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 [url=http://apod.nasa.gov/apod/ap990402.html]young blue[/url] star clusters and tell tale pinkish star forming regions. Also a result of past close encounters, a faint [url=http://burro.cwru.edu/JavaLab/GalCrashWeb/dynamic.html]tidal tail[/url] of material is just visible extending upward and left in [url=http://sleshin.startlogic.com/stargazergallery/main.php?g2_itemId=552]this deep galaxy portrait[/url].
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[c][url=http://apod.nasa.gov/apod/ap111107.html][size=150][b]Star Forming Region S106 (2011 Nov 07)[/b][/size][/url][/c]
[float=left][img6="Image Credit: GRANTECAN and IAC"]http://apod.nasa.gov/apod/image/1111/s106_canarias_900.jpg[/img6][hr][/hr][/float]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 [url=http://apod.nasa.gov/apod/ap030706.html]dust[/url] and gas orbiting Infrared Source 4 (IRS 4), visible in dark red near the image center, gives the nebula an [url=http://apod.nasa.gov/apod/ap000604.html]hourglass[/url] or [url=http://apod.nasa.gov/apod/ap090910.html]butterfly[/url] shape. [url=http://www.mpia-hd.mpg.de/IRCAM/OPRIME/Gallery/ASTRO/S106.html]S106[/url] gas near IRS 4 acts as an [url=http://apod.nasa.gov/apod/emission_nebulae.html]emission nebula[/url] as it emits light after being [url=http://csep10.phys.utk.edu/astr162/lect/light/ionization.html]ionized[/url], while [url=http://ned.ipac.caltech.edu/level5/Mathis/Mathis1.html]dust[/url] far from [url=http://adsabs.harvard.edu/abs/2009AJ....137.3149S]IRS 4[/url] reflects light from the central star and so acts as a [url=http://apod.nasa.gov/apod/reflection_nebulae.html]reflection nebula[/url]. Detailed inspection of [url=http://www.naoj.org/Pressrelease/2001/02/13/index.html]images like the above[/url] image has revealed hundreds of low-mass [url=http://en.wikipedia.org/wiki/Brown_dwarf]brown dwarf stars[/url] lurking in [url=http://adsabs.harvard.edu/abs/1998AJ....116.1868B]the nebula's[/url] gas. S106 spans about 2 [url=http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html]light-years[/url] and lies about 2000 light-years away toward the [url=http://en.wikipedia.org/wiki/Constellation]constellation[/url] of the Swan ([url=http://www.astro.wisc.edu/~dolan/constellations/constellations/Cygnus.html]Cygnus[/url]).
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[c][url=http://apod.nasa.gov/apod/ap111111.html][size=150][b]In the Arms of M83 (2011 Nov 11)[/b][/size][/url][/c]
[float=left][img6="Credit: Hubble Legacy Archive, ESA, NASA; Processing and additional imaging - Robert Gendler"]http://apod.nasa.gov/apod/image/1111/M83_HSTgendler600h.jpg[/img6][hr][/hr][/float]Big, bright, and beautiful, [url=http://www.seds.org/messier/m/m083.html]spiral galaxy M83[/url] lies a mere twelve million light-years away, near the southeastern tip of the very long constellation [url=http://www.hawastsoc.org/deepsky/hya/index.html]Hydra[/url]. This [url=http://www.robgendlerastropics.com/M83-HST-Gendler.html]cosmic close-up, a mosaic[/url] 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 [url=http://apod.nasa.gov/apod/ap061123.html]star forming regions[/url] also suggest another popular moniker for M83, [url=http://www.eso.org/public/news/eso0825/]The Thousand-Ruby Galaxy[/url]. Dominated by light from older stars, the bright yellowish core of M83 lies at the upper right. The core is also bright [url=http://apod.nasa.gov/apod/ap030206.html]at x-ray energies[/url] 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 [url=http://apod.nasa.gov/apod/ap080110.html]Centaurus A[/url]. The close-up field of view spans over 25,000 light-years at the estimated distance [url=http://hubblesite.org/newscenter/archive/releases/2009/29/]of M83[/url].
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[c][url=http://apod.nasa.gov/apod/ap111112.html][size=150][b]Sunspot Castle (2011 Nov 12)[/b][/size][/url][/c]
[float=left][img6="Image Credit & Copyright: Jens Hackmann"]http://apod.nasa.gov/apod/image/1111/SunspotCastle_hackmann900.jpg[/img6][hr][/hr][/float]Each day can have a beautiful ending as the [url=http://apod.nasa.gov/apod/ap090924.html]Sun sets[/url] below the western horizon. This week, the setting Sun added naked-eye sunspots to its finale, as enormous active regions [url=http://apod.nasa.gov/apod/ap991021.html]rotated[/url] across the dimmed, reddened solar disc. Near the Sun's center in this closing telephoto view from November 7th are sunspots in [url=http://www.youtube.com/watch?v=Nnwqkm6rL4M]Active Region 1339[/url]. Responsible for a powerful [url=http://www.nasa.gov/mission_pages/sunearth/news/News110411-x1.9-cme.html]X-class flare on November 3rd[/url], Active Region 1339 is larger than Jupiter. In the foreground, the ruined tower of a medieval castle stands in [url=http://www.kopfgeist.com/sonne_mond/sonne/sonnenuntergang_neuhaus02.htm]dramatic silhouette[/url]. Located in Igersheim, Germany and traditionally known as [url=http://de.wikipedia.org/wiki/Burg_Neuhaus_%28Igersheim%29]castle Neuhaus[/url], it might be [url=http://apod.nasa.gov/apod/ap050218.html]named[/url] Sunspot Castle for this well-composed scene.
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[c][url=http://apod.nasa.gov/apod/ap111114.html][size=150][b]Waterfall, Moonbow, and Aurora from Iceland (2011 Nov 14)[/b][/size][/url][/c]
[float=left][img6="Image Credit & Copyright: Stephane Vetter (Nuits sacrees)"]http://apod.nasa.gov/apod/image/1111/moonbow_vetter_900.jpg[/img6][hr][/hr][/float]The longer you look at [url=http://www.nuitsacrees.fr/DP/AP/apskogar_1200.jpg]this image[/url], the more you see. Perhaps your eye is first drawn to the picturesque waterfall called [url=http://en.wikipedia.org/wiki/Skogarfoss]Skogarfoss[/url] visible on the image right. Just as prevalent, however, in this [url=http://en.wikipedia.org/wiki/Iceland]Iceland[/url]ic visual extravaganza, is the colorful arc of light on the left. This [url=http://apod.nasa.gov/apod/ap010704.html]chromatic bow[/url] is not a rainbow, since the water drops did not originate in rainfall nor are they [url=http://www.cbu.edu/~jvarrian/applets/rainbow1/rainbo_z.htm]reflecting light[/url] from the Sun. Rather, the drops have drifted off from [url=http://www.youtube.com/watch?v=mbVc7RdOcFw]the waterfall[/url] and are now illuminated by the nearly [url=http://apod.nasa.gov/apod/ap070603.html]full Moon[/url]. High above are the faint green streaks of [url=http://apod.nasa.gov/apod/ap071119.html]aurora[/url]. The scene, captured one night last month, also shows a beautiful starscape far in the background, including the [url=http://apod.nasa.gov/apod/ap110624.html]Big Dipper[/url], part of the constellation of the Great Bear ([url=http://www.hawastsoc.org/deepsky/uma/index.html]Ursa Major[/url]).
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[c][url=http://apod.nasa.gov/apod/ap111121.html][size=150][b]Around the World in 90 Minutes (2011 Nov 21)[/b][/size][/url][/c]
[float=left][vimeo6]http://vimeo.com/32001208[/vimeo6]
[size=85]Video Credit: Expedition 28 & 29 Crews, ISAL, NASA's JSC;
Compilation and Editing: Michael König; Music: Do Dekor (Jan Jelinek), faitiche[/size][/float]What is it [url=http://en.wikipedia.org/wiki/Around_the_World_in_Eighty_Days]like[/url] to circle the Earth? Every 90 minutes, astronauts aboard the [url=http://apod.nasa.gov/apod/ap110309.html]International Space Station[/url] experience just that. Recently, crew members took a [url=http://blogs.discovermagazine.com/badastronomy/2011/11/13/jaw-dropping-space-station-time-lapse/]series[/url] of light-sensitive videos looking down at night that have been digitally fused to produce the [url=http://vimeo.com/32001208]above time-lapse video[/url]. Many [url=http://en.wikipedia.org/wiki/Wonders_of_the_World]wonders[/url] of the land and sky are visible in the eighteen sequences, including [url=http://apod.nasa.gov/apod/ap111028.html]red aurora[/url] above [url=http://www.webexhibits.org/causesofcolor/4D.html]green aurora[/url], 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 [url=http://www.girl-heroes.com/wp-content/uploads/2010/02/sleeping-cat.jpg]re-orienting[/url] solar panels. Please help create a useful companion guide for this moving video by [url=http://asterisk.apod.com/discuss_apod.php?date=111121]identifying[/url] landmarks, cities, countries, weather phenomena, and even background constellations that appear.
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[c][url=http://apod.nasa.gov/apod/ap111128.html][size=150][b]A Landslide on Asteroid Vesta (2011 Nov 28)[/b][/size][/url][/c]
[float=left][img6="Image Credit: NASA, JPL-Caltech, UCLA, MPS, DLR, IDA"]http://apod.nasa.gov/apod/image/1111/vestaslide_dawn_900.jpg[/img6][hr][/hr][/float]Asteroid Vesta is home to some of the most impressive cliffs in the Solar System. [url=http://photojournal.jpl.nasa.gov/catalog/PIA14716]Pictured above[/url] near the image center is a very [url=http://apod.nasa.gov/apod/ap110404.html]deep cliff[/url] running about 20 kilometers from top to bottom. The image was taken by the [url=http://dawn.jpl.nasa.gov/mission/]robotic Dawn spacecraft[/url] that began orbiting the [url=http://apod.nasa.gov/apod/ap110919.html]500-kilometer space rock[/url] earlier this year. The topography of the [url=http://apod.nasa.gov/apod/ap080723.html]scarp[/url] and its surroundings indicates that [url=http://blogs.agu.org/landslideblog/2011/10/14/a-very-large-landslide-on-the-vesta-asteroid-and-a-challenge-for-you/]huge landslides[/url] may have occurred [url=http://apod.nasa.gov/apod/ap080311.html]down[/url] 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. [url=http://planetary.org/blog/article/00003243/]Dawn has now finished[/url] up its high altitude mapping survey and will spiral down to a lower altitude orbit to better explore the asteroid's [url=http://apod.nasa.gov/apod/ap030723.html]gravitational field[/url]. During 2012, [url=http://en.wikipedia.org/wiki/Dawn_(spacecraft)]Dawn[/url] is scheduled to blast away from [url=http://www.youtube.com/watch?v=FaUaoy33gHE]Vesta[/url] and begin a long journey to the only asteroid belt object known to be larger: [url=http://apod.nasa.gov/apod/ap060821.html]Ceres[/url].
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[c][url=http://apod.nasa.gov/apod/ap111129.html][size=150][b]Across the Center of Centaurus A (2011 Nov 29)[/b][/size][/url][/c]
[float=left][img6="Image Credit: NASA, ESA, and the Hubble Heritage (STScI/AURA) - ESA/Hubble Collaboration;
Acknowledgement: R. O'Connell (U. Virginia)"]http://apod.nasa.gov/apod/image/1111/cenA2_hst_900.jpg[/img6][hr][/hr][/float]A fantastic jumble of young blue star clusters, gigantic glowing gas clouds, and imposing dark [url=http://en.wikipedia.org/wiki/Cosmic_dust]dust[/url] lanes surrounds the central region of the [url=http://imagine.gsfc.nasa.gov/docs/science/know_l1/active_galaxies.html]active galaxy[/url] Centaurus A. [url=http://hubblesite.org/newscenter/archive/releases/2011/18/image/a/]This image from the Hubble Space Telescope[/url] has been processed to present a natural color picture of this cosmic maelstrom. [url=http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/what_is_ir.html]Infrared images[/url] from the Hubble have also shown that hidden [url=http://www.youtube.com/watch?v=wYQoNHc1hug]at the center[/url] of this activity are what seem to be disks of matter spiraling into [url=http://apod.nasa.gov/apod/ap970516.html]a black hole[/url] with a billion times the mass of the Sun. [url=http://en.wikipedia.org/wiki/Centaurus_A]Centaurus A[/url] itself is apparently the result of a [url=http://apod.nasa.gov/apod/ap020202.html]collision of two galaxies[/url] and the left over debris is steadily being consumed by the [url=http://apod.nasa.gov/apod/ap971107.html]black hole[/url]. [url=http://heritage.stsci.edu/2011/18/bio/bio_primary.html]Astronomers[/url] believe that such black hole [url=http://apod.nasa.gov/apod/ap020309.html]central engines[/url] generate the [url=http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html]radio, X-ray, and gamma-ray energy[/url] radiated by Centaurus A and other [url=http://chandra.harvard.edu/xray_sources/quasars.html]active galaxies[/url]. But for an [url=http://www.astro.virginia.edu/~jh8h/glossary/activegalaxy.htm]active galaxy[/url] [url=http://apod.nasa.gov/apod/ap021111.html]Centaurus A[/url] is close, a mere 10 million [url=http://chandra.harvard.edu/photo/cosmic_distance.html]light-years[/url] away, and is a relatively convenient laboratory for exploring these [url=http://apod.nasa.gov/apod/ap110531.html]powerful sources of energy[/url].
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[size=110][url=http://asterisk.apod.com/viewtopic.php?f=29&t=25873][color=#4040FF][b]<- Previous month's poll[/b][/color][/url][/size]