_____________________________________________________________________
Please vote for the
two best APODs (image and text) for April. 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
Over 400,000 light years across
NGC 6872 is an
enormous spiral galaxy, at least 4 times the size of our own, very large, Milky Way. About 200 million light-years distant, toward the southern constellation Pavo, the Peacock, the remarkable
galaxy's stretched out shape is due to its ongoing gravitational interaction, likely leading to an eventual merger, with the nearby smaller
galaxy IC 4970. IC 4970 is seen just below and right of the giant galaxy's core in
this cosmic color portrait from the 8 meter
Gemini South telescope in Chile. The idea to image this titanic galaxy collision comes from a
winning contest essay submitted last year to the
Gemini Observatory by the Sydney Girls High School Astronomy Club. In addition to inspirational aspects and aesthetics, club members argued that a color image would be more than just a pretty picture. In their winning essay they noted that "If enough colour data is obtained in the image it may reveal easily accessible information about the different populations of stars, star formation, relative rate of star formation due to the interaction, and the extent of dust and gas present in these galaxies". (
Editor's note: For Australian schools,
2011 contest information is here.)
Have you ever seen the band of our
Milky Way Galaxy? Chances are you have never seen it like this -- nor could you. In a clear sky from a dark location at the right time, a
faint band of light is visible across the sky. This
band is the disk of our
spiral galaxy. Since we are inside this disk, the band appears to encircle the Earth. The above spectacular picture of the Milky Way arch, however, goes where the
unaided eye cannot. The image is actually a deep digital fusion of nine photos that create a panorama fully 360 across. Taken recently in
Teide National Park in
Tenerife,
Canary Islands,
Spain, the image includes the
Teide volcano, visible near the image center, behind a volcanic landscape that includes many large rocks. Far behind these Earthly structures are many sky wonders that are visible to the unaided eye, such as the band of the Milky Way, the bright
waxing Moon inside the
arch, and the
Pleiades open
star cluster (can you find it?). The deep exposure also brings out many sky wonders normally beyond
human perception, many of which are labelled on the
annotated image version, including
Barnard's Loop, visible above as the half red ring below the
Milky Way band.
This telescopic close-up shows off the otherwise faint emission nebula IC 410 in striking false-colors. It also features two remarkable inhabitants of the cosmic pond of gas and dust above and left of center, the
tadpoles of IC 410. The picture is a composite of images taken through both broad and
narrow band filters. The narrow band data
traces atoms in the nebula, with emission from sulfur atoms in red, hydrogen atoms in green, and oxygen in blue. Partly obscured by foreground dust,
the nebula itself surrounds
NGC 1893, a young galactic cluster of stars that energizes the glowing gas. Composed of denser cooler gas and dust the tadpoles are around 10 light-years long, potentially sites of ongoing star formation.
Sculpted by wind and radiation from the cluster stars, their tails trail away from the cluster's central region. IC 410 lies some 12,000 light-years away, toward the
constellation Auriga.
The
spiky stars in the foreground of
this sharp cosmic portrait are well within our own
Milky Way Galaxy. The two eye-catching galaxies lie far
beyond the Milky Way, at a distance of over 300 million light-years. Their distorted appearance is due to gravitational tides as the pair engage
in close encounters. Cataloged
as Arp 273 (also as UGC 1810), the galaxies do look
peculiar, but interacting galaxies are now understood to be common in the universe. In fact, the nearby large spiral Andromeda Galaxy is known to be some 2 million light-years away and approaching the Milky Way. Arp 273 may offer an analog of their
far future encounter. Repeated galaxy encounters on a
cosmic timescale can ultimately result in a merger into a single galaxy of stars. From our perspective, the bright cores of the Arp 273 galaxies are separated by only a little over 100,000 light-years. The release of this
stunning vista celebrates the 21st anniversary of the Hubble Space Telescope in orbit.
Well over a thousand galaxies are known members of
the Virgo Cluster, the closest large cluster of galaxies to our own
local group. In fact, the galaxy cluster is difficult
to appreciate all at once because it covers such a large area on the sky. Spanning about 5x3 degrees, this careful
mosaic of telescopic images clearly records the central region of the Virgo Cluster through faint
foreground dust clouds lingering above the plane of our own Milky Way galaxy. The cluster's dominant giant elliptical
galaxy M87, is just below center in the frame. Above M87 is the famous interacting galaxy pair NGC 4438, also known
as The Eyes. A closer examination of the image will reveal many Virgo cluster member galaxies as small fuzzy patches. Sliding your cursor over the image will label the larger galaxies using
NGC catalog designations. Galaxies are also shown with
Messier catalog numbers, including
M84, M86, and prominent colorful spirals
M88,
M90, and M91. On average, Virgo Cluster galaxies are measured to be about 48 million light-years away.
The Virgo Cluster distance has been used to give an important determination of the Hubble Constant and
the scale of the Universe. (
Editor's Note: Labels courtesy of
Astrometry.net.)
Some 60 million light-years away in the southerly
constellation Corvus, two large galaxies
collided. But the stars in the two galaxies, cataloged as
NGC 4038 and NGC 4039, don't collide in the course of the
ponderous event, lasting hundreds of millions of years. Instead, their large clouds of
molecular gas and dust do, triggering furious episodes of star formation near the center of the
cosmic wreckage. Spanning about 500 thousand light-years,
this stunning view also reveals new star clusters and
matter flung far from the scene of the accident by
gravitational tidal forces.
Of course, the suggestive visual appearance of the extended arcing structures gives the galaxy pair its popular name - The Antennae.
<- Previous month's poll
[size=200][color=#FF0000]_____________________________________________________________________[/color][/size]
Please vote for the [b]two[/b] best APODs (image and text) for April. 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=23357][color=#4040FF][b]<- Previous month's poll[/b][/color][/url][/size]
[c][url=http://apod.nasa.gov/apod/ap110403.html][size=150][b]Giant Galaxy NGC 6872 (2010 Apr 3)[/b][/size][/url][/c]
[float=left][img2]http://apod.nasa.gov/apod/image/1104/NGC6872_gemini_c800.jpg[/img2][/float]Over 400,000 light years across [url=http://www.eso.org/public/images/eso9924b/]NGC 6872 is[/url] an [url=http://arxiv.org/abs/astro-ph/0701291]enormous spiral galaxy[/url], at least 4 times the size of our own, very large, Milky Way. About 200 million light-years distant, toward the southern constellation Pavo, the Peacock, the remarkable [url=http://burro.cwru.edu/JavaLab/GalCrashWeb/]galaxy's stretched out shape[/url] is due to its ongoing gravitational interaction, likely leading to an eventual merger, with the nearby smaller [url=http://chandra.harvard.edu/photo/2009/ngc6872/]galaxy IC 4970[/url]. IC 4970 is seen just below and right of the giant galaxy's core in [url=http://www.gemini.edu/node/11625]this cosmic color portrait[/url] from the 8 meter [url=http://apod.nasa.gov/apod/ap030909.html]Gemini South telescope[/url] in Chile. The idea to image this titanic galaxy collision comes from a [url=http://ausgo.aao.gov.au/contest2010/]winning contest essay[/url] submitted last year to the [url=http://www.gemini.edu/index.php?q=node/132]Gemini Observatory[/url] by the Sydney Girls High School Astronomy Club. In addition to inspirational aspects and aesthetics, club members argued that a color image would be more than just a pretty picture. In their winning essay they noted that "If enough colour data is obtained in the image it may reveal easily accessible information about the different populations of stars, star formation, relative rate of star formation due to the interaction, and the extent of dust and gas present in these galaxies". ([i]Editor's note:[/i] For Australian schools, [url=http://ausgo.aao.gov.au/contest/]2011 contest information is here.[/url])
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[c][url=http://apod.nasa.gov/apod/ap110405.html][size=150][b]The Milky Way Over Tenerife (2010 Apr 5)[/b][/size][/url][/c]
[float=left][img2]http://apod.nasa.gov/apod/image/1104/teidesky_casado_1726.jpg[/img2][/float]Have you ever seen the band of our [url=http://casswww.ucsd.edu/public/tutorial/MW.html]Milky Way Galaxy[/url]? Chances are you have never seen it like this -- nor could you. In a clear sky from a dark location at the right time, a [url=http://apod.nasa.gov/apod/ap011205.html]faint band of light[/url] is visible across the sky. This [url=http://apod.nasa.gov/apod/ap070930.html]band[/url] is the disk of our [url=http://www.seds.org/messier/spir.html]spiral galaxy[/url]. Since we are inside this disk, the band appears to encircle the Earth. The above spectacular picture of the Milky Way arch, however, goes where the [url=http://webphysics.davidson.edu/physlet_resources/dav_optics/examples/eye_demo.html]unaided eye[/url] cannot. The image is actually a deep digital fusion of nine photos that create a panorama fully 360 across. Taken recently in [url=http://www.youtube.com/watch?v=JIPGbwf3228]Teide National Park[/url] in [url=http://en.wikipedia.org/wiki/Tenerife]Tenerife[/url], [url=http://en.wikipedia.org/wiki/Canary_Islands]Canary Islands[/url], [url=http://en.wikipedia.org/wiki/Spain]Spain[/url], the image includes the [url=http://en.wikipedia.org/wiki/File:Teide_and_it%27s_CableCar_-_P1.jpg]Teide volcano[/url], visible near the image center, behind a volcanic landscape that includes many large rocks. Far behind these Earthly structures are many sky wonders that are visible to the unaided eye, such as the band of the Milky Way, the bright [url=http://en.wikipedia.org/wiki/File:Lunar-Phase-Diagram.png]waxing Moon[/url] inside the [url=http://apod.nasa.gov/apod/ap080713.html]arch[/url], and the [url=http://apod.nasa.gov/apod/ap091014.html]Pleiades[/url] open [url=http://asterisk.apod.com/viewtopic.php?f=24&t=18009]star cluster[/url] (can you find it?). The deep exposure also brings out many sky wonders normally beyond [url=http://apod.nasa.gov/apod/ap091004.html]human perception[/url], many of which are labelled on the [url=http://apod.nasa.gov/apod/image/1104/teidesky_casado_annotated_3000.jpg]annotated image version[/url], including [url=http://apod.nasa.gov/apod/ap090224.html]Barnard's Loop[/url], visible above as the half red ring below the [url=http://www.youtube.com/watch?v=a358QLi4Wgs]Milky Way band[/url].
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[c][url=http://apod.nasa.gov/apod/ap110416.html][size=150][b]The Tadpoles of IC 410 (2010 Apr 16)[/b][/size][/url][/c]
[float=left][img2]http://apod.nasa.gov/apod/image/1104/IC410_hanson900.jpg[/img2][/float]This telescopic close-up shows off the otherwise faint emission nebula IC 410 in striking false-colors. It also features two remarkable inhabitants of the cosmic pond of gas and dust above and left of center, the [url=http://www.countrysideinfo.co.uk/metindex.htm]tadpoles[/url] of IC 410. The picture is a composite of images taken through both broad and [url=http://hubblesite.org/gallery/behind_the_pictures/meaning_of_color/eagle.php]narrow band filters[/url]. The narrow band data [url=http://apod.nasa.gov/apod/ap060324.html]traces atoms[/url] in the nebula, with emission from sulfur atoms in red, hydrogen atoms in green, and oxygen in blue. Partly obscured by foreground dust, [url=http://apod.nasa.gov/apod/ap060815.html]the nebula itself[/url] surrounds [url=http://www.arxiv.org/abs/astro-ph?papernum=9909065]NGC 1893[/url], a young galactic cluster of stars that energizes the glowing gas. Composed of denser cooler gas and dust the tadpoles are around 10 light-years long, potentially sites of ongoing star formation. [url=http://apod.nasa.gov/apod/ap050425.html]Sculpted by[/url] wind and radiation from the cluster stars, their tails trail away from the cluster's central region. IC 410 lies some 12,000 light-years away, toward the [url=http://apod.nasa.gov/apod/ap100305.html]constellation Auriga[/url].
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[c][url=http://apod.nasa.gov/apod/ap110421.html][size=150][b]Peculiar Galaxies of Arp 273 (2010 Apr 21)[/b][/size][/url][/c]
[float=left][img2]http://apod.nasa.gov/apod/image/1104/arp273_hst900.jpg[/img2][/float]The [url=http://spider.ipac.caltech.edu/staff/kaspar/obs_mishaps/images/int_reflection2.html]spiky[/url] stars in the foreground of [url=http://heritage.stsci.edu/2011/11/index.html]this sharp cosmic portrait[/url] are well within our own [url=http://www.atlasoftheuniverse.com/galaxy.html]Milky Way Galaxy[/url]. The two eye-catching galaxies lie far [url=http://apod.nasa.gov/apod/ap070712.html]beyond the Milky Way[/url], at a distance of over 300 million light-years. Their distorted appearance is due to gravitational tides as the pair engage [url=http://burro.cwru.edu/JavaLab/GalCrashWeb/backgrnd.html]in close encounters[/url]. Cataloged [url=http://www.noao.edu/image_gallery/html/im0011.html]as Arp 273[/url] (also as UGC 1810), the galaxies do look [url=http://nedwww.ipac.caltech.edu/level5/Arp/frames.html]peculiar[/url], but interacting galaxies are now understood to be common in the universe. In fact, the nearby large spiral Andromeda Galaxy is known to be some 2 million light-years away and approaching the Milky Way. Arp 273 may offer an analog of their [url=http://hubblesite.org/newscenter/archive/releases/galaxy/2002/09/]far future encounter[/url]. Repeated galaxy encounters on a [url=http://apod.nasa.gov/apod/ap060323.html]cosmic timescale[/url] can ultimately result in a merger into a single galaxy of stars. From our perspective, the bright cores of the Arp 273 galaxies are separated by only a little over 100,000 light-years. The release of this [url=http://hubblesite.org/newscenter/archive/releases/2011/11/]stunning vista celebrates[/url] the 21st anniversary of the Hubble Space Telescope in orbit.
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[c][url=http://apod.nasa.gov/apod/ap110422.html][size=150][b]Virgo Cluster Galaxies (2010 Apr 22)[/b][/size][/url][/c]
[float=left][img2]http://apod.nasa.gov/apod/image/1104/201103_VirgoGCM_andreo900.jpg[/img2][/float]Well over a thousand galaxies are known members of [url=http://www.seds.org/messier/more/virgo.html]the Virgo Cluster[/url], the closest large cluster of galaxies to our own [url=http://www.atlasoftheuniverse.com/localgr.html]local group[/url]. In fact, the galaxy cluster is difficult [url=http://www.atlasoftheuniverse.com/galgrps/vir.html]to appreciate[/url] all at once because it covers such a large area on the sky. Spanning about 5x3 degrees, this careful [url=http://blog.deepskycolors.com/archive/2011/03/18/virgo-Cluster-Deep-Widefield.html]mosaic of telescopic images[/url] clearly records the central region of the Virgo Cluster through faint [url=http://www.galaxyimages.com/UNP1.html]foreground dust[/url] clouds lingering above the plane of our own Milky Way galaxy. The cluster's dominant giant elliptical [url=http://apod.nasa.gov/apod/ap100520.html]galaxy M87[/url], is just below center in the frame. Above M87 is the famous interacting galaxy pair NGC 4438, also known [url=http://apod.nasa.gov/apod/ap070608.html]as The Eyes[/url]. A closer examination of the image will reveal many Virgo cluster member galaxies as small fuzzy patches. Sliding your cursor over the image will label the larger galaxies using [url=http://apod.nasa.gov/apod/ap990429.html]NGC catalog[/url] designations. Galaxies are also shown with [url=http://www.seds.org/messier/xtra/history/m-cat-i.html]Messier catalog[/url] numbers, including [url=http://apod.nasa.gov/apod/ap080425.html]M84, M86[/url], and prominent colorful spirals [url=http://apod.nasa.gov/apod/ap100130.html]M88[/url], [url=http://apod.nasa.gov/apod/ap960316.html]M90[/url], and M91. On average, Virgo Cluster galaxies are measured to be about 48 million light-years away. [url=http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1996PASP%2E%2E108%2E1091V]The Virgo Cluster distance[/url] has been used to give an important determination of the Hubble Constant and [url=http://antwrp.gsfc.nasa.gov/diamond_jubilee/debate96.html]the scale of the Universe[/url]. ([i]Editor's Note:[/i] Labels courtesy of [url=http://astrometry.net/]Astrometry.net[/url].)
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[c][url=http://apod.nasa.gov/apod/ap110429.html][size=150][b]The Antennae (2010 Apr 29)[/b][/size][/url][/c]
[float=left][img2]http://apod.nasa.gov/apod/image/1104/ngc4038_HagarOreshko900c.jpg[/img2][/float]Some 60 million light-years away in the southerly [url=http://hawastsoc.org/deepsky/crv/index.html]constellation Corvus[/url], two large galaxies [url=http://hubblesite.org/newscenter/newsdesk/archive/releases/1997/34/]collided[/url]. But the stars in the two galaxies, cataloged as [url=http://www.cv.nrao.edu/~jhibbard/n4038/]NGC 4038 and NGC 4039[/url], don't collide in the course of the [url=http://www.cita.utoronto.ca/~dubinski/antennae/antennae.html]ponderous event[/url], lasting hundreds of millions of years. Instead, their large clouds of [url=http://archive.ncsa.uiuc.edu/Cyberia/Bima/GMC.html]molecular gas[/url] and dust do, triggering furious episodes of star formation near the center of the [url=http://apod.nasa.gov/apod/ap061024.html]cosmic wreckage[/url]. Spanning about 500 thousand light-years, [url=http://www.stargazer-observatory.com/ngc4038.html]this stunning view[/url] also reveals new star clusters and [url=http://apod.nasa.gov/apod/ap090426.html]matter flung far[/url] from the scene of the accident by [url=http://xxx.lanl.gov/abs/astro-ph/0307383]gravitational tidal[/url] forces. [url=http://burro.cwru.edu/JavaLab/GalCrashWeb/]Of course[/url], the suggestive visual appearance of the extended arcing structures gives the galaxy pair its popular name - The Antennae.
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[c][url=http://apod.nasa.gov/apod/ap110430.html][size=150][b]Tycho's Supernova Remnant (2010 Apr 30)[/b][/size][/url][/c]
[float=left][img2]http://apod.nasa.gov/apod/image/1104/tychosnr_chandra900c.jpg[/img2][/float][c][url=http://asterisk.apod.com/discuss_apod.php?date=110430]Tycho! Tycho![/url] burning bright
In the darkness of the night,
[url=http://chandra.harvard.edu/photo/2011/tycho2/]What exploding white dwarf star[/url]
Did frame thy remnant from afar,
In the distant deep dark skies
Under gaze of human eyes?
Seen by mortals and their ma
Named for one called [url=http://galileo.rice.edu/sci/brahe.html]Tycho Brahe.[/url][/c]
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[size=110][url=http://asterisk.apod.com/viewtopic.php?f=29&t=23357][color=#4040FF][b]<- Previous month's poll[/b][/color][/url][/size]