by owlice » Tue Oct 11, 2011 2:22 am
_____________________________________________________________________
Please vote for the
two best APODs (image and text) for September, 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
While hunting for comets in the skies above 18th century France,
astronomer Charles Messier diligently kept a list of the things he encountered that were definitely not comets. This is number 27 on his
now famous not-a-comet list. In fact, 21st century astronomers would identify it as a
planetary nebula, but it's not a planet either, even though it may
appear round and planet-like in a small telescope. Messier 27 (M27) is an excellent example of a
gaseous emission nebula created as a
sun-like star runs out of nuclear fuel in its core. The nebula forms as the star's outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star's intense but invisible
ultraviolet light. Known by the popular name of the
Dumbbell Nebula, the beautifully symmetric interstellar gas cloud is over 2.5 light-years across and about 1,200 light-years away in the
constellation Vulpecula. This impressive color composite highlights details within the well-studied central region and fainter, seldom imaged features in the nebula's
outer halo. It incorporates broad and narrowband images
recorded using filters sensitive to emission from sulfur, hydrogen and oxygen atoms.
This view of the Apollo 17 landing site in the Taurus-Littrow valley was captured last month by the Lunar Reconnaissance Orbiter (LRO), the sharpest ever
recorded from space.
The high resolution image data was taken during a period when LRO's orbit was modified to create a close approach of about 22 kilometers as it passed over some of the Apollo landing sites. That altitude corresponds to only about twice the height of a commercial airline flight over planet Earth. Labeled in this image are Apollo 17 lunar lander
Challenger's descent stage (inset), the
lunar rover (LRV) at its final
parking spot, and the Apollo Lunar Surface Experiments Package (ALSEP)
left to monitor the Moon's environment and interior. Clear, dual lunar rover
tracks and the foot trails left by astronauts
Eugene Cernan and Harrison Schmitt, the last to walk on the lunar surface, are also easily visible at the
Apollo 17 site.
Gorgeous spiral galaxy
NGC 3521 is a mere 35 million light-years away, toward the
constellation Leo. Relatively bright in planet Earth's sky, NGC 3521 is easily visible in small telescopes but often overlooked by amateur imagers in favor of other Leo spiral galaxies, like
M66 and M65. It's hard to overlook in
this colorful cosmic portrait, though. Spanning some 50,000 light-years the galaxy sports
characteristic patchy, irregular spiral arms laced with dust, pink star forming regions, and clusters of young, blue stars. Remarkably, this deep image also finds NGC 3521 embedded in gigantic bubble-like shells. The shells are likely tidal debris, streams of stars torn from satellite galaxies that have
undergone mergers with NGC 3521 in the distant past.
September's
equinox arrives today at 0905 UT. As the Sun crosses the celestial equator heading south, spring begins in the southern hemisphere and autumn in the north. And though
the seasonal connection is still puzzling, both spring and autumn bring an increase in geomagnetic storms. So as northern nights grow longer, the equinox also heralds the arrival of a good season for
viewing aurora. Recorded earlier this month,
these curtains of September's
shimmering green light sprawl across a gorgeous night skyscape. In the foreground lies Hidden Lake Territorial Park near Yellowknife, Northwest Territories, Canada. Calm water reflects the aurora, with bright star trails peering through the
mesmerizing sky glow. Of course, shining at altitudes of 100 kilometers or so, planet Earth's auroras are
visible from space.
Part of Mars is defrosting. Around the
South Pole of Mars, toward the end of every Martian summer, the warm weather causes a section of the vast carbon-dioxide ice cap to evaporate.
Pits begin to appear and expand where the carbon dioxide dry
ice sublimates directly into gas. These ice sheet pits may appear to be lined with gold, but the precise composition of the dust that highlights the pit
walls actually remains unknown. The
circular depressions toward the image center measure about 60 meters across. The
HiRISE camera aboard the Mars-orbiting
Mars Reconnaissance Orbiter captured the
above image in late July. In the next few months, as Mars continues its
journey around the
Sun, colder seasons will prevail, and the thin air will turn chilly enough not only to stop the defrosting but once again freeze out more layers of
solid carbon dioxide.
Click to play embedded YouTube video.
Have you ever dreamed of flying high above the Earth? Astronauts visiting the
International Space Station do this every day, circling our restless planet twice every three hours. A dramatic example of their view was compiled in the
above time-lapse video from images taken earlier this month. As the ISS speeds into the
nighttime half of the globe, familiar constellations of stars remain visible above. An aerosol
haze of Earth's
thin atmosphere is visible on the horizon as an thin multi-colored ring. Many
wonders whiz by below, including vast banks of white clouds, large stretches of deep blue sea, land lit up by the lights of big cities and small towns, and storm clouds flashing with
lightning. The
video starts
over the northern Pacific Ocean and then passes from western North
America to western South America, ending near
Antarctica as daylight finally approaches.
<- Previous month's poll
[size=200][color=#FF0000]_____________________________________________________________________[/color][/size]
Please vote for the [b]two[/b] best APODs (image and text) for September, 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=25218][color=#4040FF][b]<- Previous month's poll[/b][/color][/url][/size]
[hr][/hr]
[c][url=http://apod.nasa.gov/apod/ap110901.html][size=150][b]M27: Not a Comet (2011 September 01)[/b][/size][/url][/c]
[float=left][img6="[size=85]Image Credit & Copyright: Martin Pugh[/size]"]http://apod.nasa.gov/apod/image/1109/M27NarrowBroad_pugh900.jpg[/img6][/float]While hunting for comets in the skies above 18th century France, [url=http://www.seds.org/messier/xtra/history/biograph.html]astronomer Charles Messier[/url] diligently kept a list of the things he encountered that were definitely not comets. This is number 27 on his [url=http://www.seds.org/messier/xtra/history/m-cat.html]now famous not-a-comet list[/url]. In fact, 21st century astronomers would identify it as a [url=http://www.seds.org/messier/planetar.html]planetary nebula[/url], but it's not a planet either, even though it may [url=http://apod.nasa.gov/apod/ap030614.html]appear round[/url] and planet-like in a small telescope. Messier 27 (M27) is an excellent example of a [url=http://www.astro.washington.edu/balick/WFPC2/]gaseous emission nebula[/url] created as a [url=http://apod.nasa.gov/apod/ap100221.html]sun-like star runs out[/url] of nuclear fuel in its core. The nebula forms as the star's outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star's intense but invisible [url=http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html]ultraviolet light[/url]. Known by the popular name of the [url=http://www.seds.org/messier/m/m027.html]Dumbbell Nebula[/url], the beautifully symmetric interstellar gas cloud is over 2.5 light-years across and about 1,200 light-years away in the [url=http://hawastsoc.org/deepsky/vul/index.html]constellation Vulpecula[/url]. This impressive color composite highlights details within the well-studied central region and fainter, seldom imaged features in the nebula's [url=http://apod.nasa.gov/apod/ap100509.html]outer halo[/url]. It incorporates broad and narrowband images [url=http://www.martinpughastrophotography.id.au/Heavens_Mirror.htm]recorded using[/url] filters sensitive to emission from sulfur, hydrogen and oxygen atoms.
[clear][/clear]
[hr][/hr]
[c][url=http://apod.nasa.gov/apod/ap110908.html][size=150][b]Apollo 17 Site: A Sharper View (2011 Sept 08)[/b][/size][/url][/c]
[float=left][img6="[size=85]Credit: NASA / GSFC / Arizona State Univ. / Lunar Reconnaissance Orbiter[/size]"]http://apod.nasa.gov/apod/image/1109/apollo17area1_lro900.jpg[/img6][/float][url=http://www.nasa.gov/mission_pages/LRO/news/apollo-sites.html]This view of the Apollo 17[/url] landing site in the Taurus-Littrow valley was captured last month by the Lunar Reconnaissance Orbiter (LRO), the sharpest ever [url=http://apod.nasa.gov/apod/ap020628.html]recorded from space[/url]. [url=http://lroc.sese.asu.edu/news/?archives/454-Skimming-the-Moon.html]The high resolution image[/url] data was taken during a period when LRO's orbit was modified to create a close approach of about 22 kilometers as it passed over some of the Apollo landing sites. That altitude corresponds to only about twice the height of a commercial airline flight over planet Earth. Labeled in this image are Apollo 17 lunar lander [url=http://apod.nasa.gov/apod/ap060107.html]Challenger's[/url] descent stage (inset), the [url=http://apod.nasa.gov/apod/ap040605.html]lunar rover[/url] (LRV) at its final [url=http://apod.nasa.gov/apod/ap080706.html]parking spot[/url], and the Apollo Lunar Surface Experiments Package (ALSEP) [url=http://www.lpi.usra.edu/expmoon/Apollo17/A17_science.html]left to monitor[/url] the Moon's environment and interior. Clear, dual lunar rover [url=http://apod.nasa.gov/apod/ap040417.html]tracks[/url] and the foot trails left by astronauts [url=http://apod.nasa.gov/apod/ap051217.html]Eugene Cernan and Harrison Schmitt[/url], the last to walk on the lunar surface, are also easily visible at the [url=http://www.lpi.usra.edu/expmoon/Apollo17/A17_lsite.html]Apollo 17 site[/url].
[clear][/clear]
[hr][/hr]
[c][url=http://apod.nasa.gov/apod/ap110915.html][size=150][b]NGC 3521: Galaxy in a Bubble (2011 Sept 15)[/b][/size][/url][/c]
[float=left][img6="[size=85]Image Credit & Copyright: R Jay Gabany (Blackbird Obs.), Collaboration: David Martinez-Delgado (MPIA, IAC), et al.[/size]"]http://apod.nasa.gov/apod/image/1109/ngc3521_gabany901.jpg[/img6][/float]Gorgeous spiral galaxy [url=http://apod.nasa.gov/apod/ap110113.html]NGC 3521 is[/url] a mere 35 million light-years away, toward the [url=http://www.universetoday.com/21173/leo/]constellation Leo[/url]. Relatively bright in planet Earth's sky, NGC 3521 is easily visible in small telescopes but often overlooked by amateur imagers in favor of other Leo spiral galaxies, like [url=http://apod.nasa.gov/apod/ap110803.html]M66 and M65[/url]. It's hard to overlook in [url=http://www.cosmotography.com/images/small_ngc3521.html]this colorful cosmic portrait[/url], though. Spanning some 50,000 light-years the galaxy sports [url=http://adsabs.harvard.edu/abs/1982MNRAS.201.1021E]characteristic[/url] patchy, irregular spiral arms laced with dust, pink star forming regions, and clusters of young, blue stars. Remarkably, this deep image also finds NGC 3521 embedded in gigantic bubble-like shells. The shells are likely tidal debris, streams of stars torn from satellite galaxies that have [url=http://www.cosmotography.com/images/galaxy_formation_and_evolution.html]undergone mergers[/url] with NGC 3521 in the distant past.
[clear][/clear]
[hr][/hr]
[c][url=http://apod.nasa.gov/apod/ap110923.html][size=150][b]September's Aurora (2011 Sept 23)[/b][/size][/url][/c]
[float=left][img6="[size=85]Image Credit & Copyright: Yuichi Takasaka / TWAN / http://www.blue-moon.ca[/size]"]http://apod.nasa.gov/apod/image/1109/C404-5244-6082AuroraTakasaka900.jpg[/img6][/float]September's [url=http://apod.nasa.gov/apod/ap070923.html]equinox[/url] arrives today at 0905 UT. As the Sun crosses the celestial equator heading south, spring begins in the southern hemisphere and autumn in the north. And though [url=http://science.nasa.gov/science-news/science-at-nasa/2001/ast26oct_1/]the seasonal connection[/url] is still puzzling, both spring and autumn bring an increase in geomagnetic storms. So as northern nights grow longer, the equinox also heralds the arrival of a good season for [url=http://www.spaceweather.com/aurora/gallery_01sep11_page3.htm]viewing aurora[/url]. Recorded earlier this month, [url=http://www.blue-moon.ca/2011sep.html]these curtains[/url] of September's [url=http://www.youtube.com/ytakasaka#p/u/2/Z2gLfDk4N1o]shimmering green light[/url] sprawl across a gorgeous night skyscape. In the foreground lies Hidden Lake Territorial Park near Yellowknife, Northwest Territories, Canada. Calm water reflects the aurora, with bright star trails peering through the [url=http://apod.nasa.gov/apod/ap091219.html]mesmerizing sky glow[/url]. Of course, shining at altitudes of 100 kilometers or so, planet Earth's auroras are [url=http://www.nasa.gov/multimedia/videogallery/index.html?media_id=112491731]visible from space[/url].
[clear][/clear]
[hr][/hr]
[c][url=http://apod.nasa.gov/apod/ap110926.html][size=150][b]Dry Ice Pits on Mars (2011 Sept 26)[/b][/size][/url][/c]
[float=left][img6="[size=85]Image Credit: HiRISE, MRO, LPL (U. Arizona), NASA[/size]"]http://apod.nasa.gov/apod/image/1109/dryice_mro_900.jpg[/img6][/float]Part of Mars is defrosting. Around the [url=http://apod.nasa.gov/apod/ap011213.html]South Pole[/url] of Mars, toward the end of every Martian summer, the warm weather causes a section of the vast carbon-dioxide ice cap to evaporate. [url=http://apod.nasa.gov/apod/ap070928.html]Pits[/url] begin to appear and expand where the carbon dioxide dry [url=http://www.youtube.com/watch?v=pP_lZaOchE0]ice sublimates[/url] directly into gas. These ice sheet pits may appear to be lined with gold, but the precise composition of the dust that highlights the pit [url=http://apod.nasa.gov/apod/ap080723.html]walls[/url] actually remains unknown. The [url=http://apod.nasa.gov/apod/ap010327.html]circular depressions[/url] toward the image center measure about 60 meters across. The [url=http://en.wikipedia.org/wiki/HiRISE]HiRISE[/url] camera aboard the Mars-orbiting [url=http://mars.jpl.nasa.gov/mro/mission/overview/]Mars Reconnaissance Orbiter[/url] captured the [url=http://www.uahirise.org/ESP_023464_0945]above image[/url] in late July. In the next few months, as Mars continues its [url=http://planetary.org/explore/topics/mars/calendar.html]journey around[/url] the [url=http://asterisk.apod.com/viewtopic.php?f=24&t=18012]Sun[/url], colder seasons will prevail, and the thin air will turn chilly enough not only to stop the defrosting but once again freeze out more layers of [url=http://www.dryiceinfo.com/science.htm]solid carbon dioxide[/url].
[clear][/clear]
[hr][/hr]
[c][url=http://apod.nasa.gov/apod/ap110927.html][size=150][b]Flying Over Planet Earth (2011 Sept 27)[/b][/size][/url][/c]
[float=left][youtube6]http://www.youtube.com/watch?v=74mhQyuyELQ[/youtube6]
[size=85]Image Credit: NASA; Acknowledgement: Infinity Imagined[/size][/float]Have you ever dreamed of flying high above the Earth? Astronauts visiting the [url=http://apod.nasa.gov/apod/ap110309.html]International Space Station[/url] do this every day, circling our restless planet twice every three hours. A dramatic example of their view was compiled in the [url=http://infinity-imagined.tumblr.com/post/10336160505/a-time-lapse-taken-from-the-front-of-the]above time-lapse video[/url] from images taken earlier this month. As the ISS speeds into the [url=http://apod.nasa.gov/apod/image/0810/earthlights2_dmsp_big.jpg]nighttime[/url] half of the globe, familiar constellations of stars remain visible above. An aerosol [url=http://blogs.discovermagazine.com/badastronomy/2011/09/17/flying-around-the-earth/]haze[/url] of Earth's [url=http://apod.nasa.gov/apod/ap100623.html]thin atmosphere[/url] is visible on the horizon as an thin multi-colored ring. Many [url=http://www.universetoday.com/88998/amazing-timelapse-video-from-the-space-station/]wonders[/url] whiz by below, including vast banks of white clouds, large stretches of deep blue sea, land lit up by the lights of big cities and small towns, and storm clouds flashing with [url=http://www.youtube.com/watch?v=Sn65RFvJKnk]lightning[/url]. The [url=http://www.youtube.com/watch?v=74mhQyuyELQ]video[/url] starts [url=http://spaceflight.nasa.gov/realdata/tracking/]over[/url] the northern Pacific Ocean and then passes from western North [url=http://en.wikipedia.org/wiki/Americas]America[/url] to western South America, ending near [url=http://apod.nasa.gov/apod/ap080907.html]Antarctica[/url] as daylight finally approaches.
[clear][/clear]
[hr][/hr]
[size=110][url=http://asterisk.apod.com/viewtopic.php?f=29&t=25218][color=#4040FF][b]<- Previous month's poll[/b][/color][/url][/size]