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Dawn of Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL)
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Phoebe's Radiation
| Description |
Phoebe's Radiation |
| Full Description |
This image shows thermal radiation from the day and night sides of Saturn's moon Phoebe, taken by the composite infrared spectrometer onboard Cassini 1.8 hours before the spacecraft's closest approach to Phoebe on June 11, 2004. The left-hand panel displays the image in grayscale format, showing the brightness of Phoebe's radiation in the wavelength range 15-17 microns, which is about 25 times the longest wavelength visible to the naked eye. In the middle panel this brightness is used to estimate the surface temperature distribution across Phoebe. Temperatures are given in degrees Kelvin, and vary from a relatively toasty 107 Kelvin (-267 Fahrenheit), in the late morning near the equator (white, lower right), to less than 75 Kelvin (-324 Fahrenheit) in the northern hemisphere in the pre-dawn hours (dark blue, upper left). The "ragged edge" of Phoebe in this region is an instrumental artifact. Temperatures are affected strongly by topography, as can be seen by comparison with the visible-wavelength image (right). Some of the coldest temperatures are found in the shadowed region inside the large depression in the northern hemisphere (upper right). The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini composite infrared spectrometer home page at http://cirs.gsfc.nasa.gov/ . Image Credit: NASA/JPL/Goddard Space Flight Center |
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Phoebe Temperature Maps
| Description |
Phoebe Temperature Maps |
| Full Description |
A montage of maps of Saturn's moon Phoebe shows surface temperatures at various times of day as determined by the composite infrared spectrometer onboard Cassini during the June 11, 2004, Phoebe flyby. The asterisk on each map shows the location of the subsolar point, where the Sun is directly overhead. This point moves across the surface as Phoebe rotates. It is morning in regions to the left of the subsolar point, and afternoon in regions to the right. Like a newspaper weather map, different colors indicate different temperatures, though Phoebe's temperatures are distinctly cooler than even the coldest January day on Earth. Equatorial temperatures peak in the early afternoon near 112 Kelvin (-257 Fahrenheit), plunging to 78 Kelvin (-319 Fahrenheit) before dawn, and are even colder at higher latitudes. The large day/night temperature contrasts imply that Phoebe's surface is covered in loose dust or ice particles that store little heat and thus cool off rapidly at night. Regions of Phoebe's surface that were not observed are shown in black. Most of the maps show the effect on surface temperatures of the large crater-like depression seen in Cassini's visible-wavelength images of Phoebe, which is located just left of center in these maps. Crater walls that are shadowed and cold in the early morning in the first map are sunlit and warm in the late afternoon in the final map. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini composite infrared spectrometer home page at http://cirs.gsfc.nasa.gov/ . Image Credit: NASA/JPL/Goddard Space Flight Center |
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Mount St. Helens
| Title |
Mount St. Helens |
| Description |
Hot lava had broken through the surface of the growing lava dome on Mount St. Helens when the MASTER sensor took this image in the early morning hours of October 13, 2004. MASTER, which stands for MODIS/ASTER Airborne Simulator, is an aircraft- mounted remote sensing device built to simulate the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov/ ]) and Advanced Spaceborne Thermal Emission and Reflection Radiometer [ http://asterweb.jpl.nasa.gov/ ] (ASTER) instruments on NASA's Terra [ http://terra.nasa.gov/ ] satellite. The top image was made from MASTER's thermal sensitive bands, and shows the heat in the volcano's crater. A brilliant white spot on the southwest side of the crater is hot lava bubbling to the surface. Smaller, less intense hot spots around the crater have formed where magma near the surface has heated the rock above it. The dark area around the lava dome is the crater. Shielded from the sun and covered with snow, the dark crater floor is cooler than the surrounding landscape, which appears red. A plume of steam rising from the lava dome (colored purple) drifts southeast in this image. The plume and crater floor are more visible in the lower, true color image. Acquired just after dawn, the image has few shadows and low contrast. An image composed of thermal infrared and visible light wavelengths reveals more details around the mountain. The volcanic plume is bright cyan, the cool crater is purple, and snow is light blue. To the north of the volcano, two bright red lines extend from south to north. These are warm-water streams, possibly heated by the active volcano. NASA images courtesy Jeff Myers, MASTER [ http://masterweb.jpl.nasa.gov/ ] instrument team, NASA Ames Research Center |
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Mount St. Helens
| Title |
Mount St. Helens |
| Description |
Hot lava had broken through the surface of the growing lava dome on Mount St. Helens when the MASTER sensor took this image in the early morning hours of October 13, 2004. MASTER, which stands for MODIS/ASTER Airborne Simulator, is an aircraft- mounted remote sensing device built to simulate the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov/ ]) and Advanced Spaceborne Thermal Emission and Reflection Radiometer [ http://asterweb.jpl.nasa.gov/ ] (ASTER) instruments on NASA's Terra [ http://terra.nasa.gov/ ] satellite. The top image was made from MASTER's thermal sensitive bands, and shows the heat in the volcano's crater. A brilliant white spot on the southwest side of the crater is hot lava bubbling to the surface. Smaller, less intense hot spots around the crater have formed where magma near the surface has heated the rock above it. The dark area around the lava dome is the crater. Shielded from the sun and covered with snow, the dark crater floor is cooler than the surrounding landscape, which appears red. A plume of steam rising from the lava dome (colored purple) drifts southeast in this image. The plume and crater floor are more visible in the lower, true color image. Acquired just after dawn, the image has few shadows and low contrast. An image composed of thermal infrared and visible light wavelengths reveals more details around the mountain. The volcanic plume is bright cyan, the cool crater is purple, and snow is light blue. To the north of the volcano, two bright red lines extend from south to north. These are warm-water streams, possibly heated by the active volcano. NASA images courtesy Jeff Myers, MASTER [ http://masterweb.jpl.nasa.gov/ ] instrument team, NASA Ames Research Center |
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Sky and Planets
| Title |
Sky and Planets |
| Explanation |
On February 10th, an evocative [ http://www.jps.net/ssumner/ ] evening sky above Rocklin, California, USA inspired astrophotographer Steve Sumner to record this remarkable sight - five planets and the Moon. Near its first quarter phase, the bright Moon [ http://lunar.arc.nasa.gov/ ] was intentionally overexposed but Saturn [ http://www.jpl.nasa.gov/cassini/ ], Jupiter [ http://galileo.jpl.nasa.gov/ ], Mars [ http://mars.jpl.nasa.gov/ ], and Mercury [ http://sd-www.jhuapl.edu/MESSENGER/ ] (and, of course, planet Earth's [ http://www.earth.nasa.gov/ ] horizon) are all clearly visible in the deepening twilight. Notably absent in this grouping of naked-eye planets is Venus [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html ] which is still putting in an early appearance as the morning star [ http://ispec.scibernet.com/station/morn_star.html ]. This month, Mercury has joined Venus in the dawn twilight while Saturn, Jupiter, and Mars still shine brightly in the western sky at nightfall [ http://www.skypub.com/sights/sights.shtml ] making another gorgeous close grouping with the crescent Moon [ http://www.inconstantmoon.com/ ]. |
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Comet Meets Ring Nebula: Par
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| Title |
Comet Meets Ring Nebula: Part I |
| Explanation |
As dawn approached on May 8, astronomer Stefan Seip carefully watched Fragment C of broken [ http://neo.jpl.nasa.gov/cgi-bin/db?name=73P ] comet 73P/Schwassmann-Wachmann 3 [ http://skyandtelescope.com/observing/objects/comets/ article_1704_1.asp ] approach M57 [ http://seds.lpl.arizona.edu/messier/m/m057.html ] - the Ring Nebula, and faint spiral galaxy IC 1296 [ http://www.skyhound.com/sh/archive/jul/IC_1296.html ]. Of course, even though the trio seemed to come close together in a truly cosmic photo opportunity, the comet [ http://antwrp.gsfc.nasa.gov/apod/ap060504.html ] is in the inner part of our solar system, a mere 0.5 light-minutes [ http://en.wikipedia.org/wiki/Light-minute ] or so from Seip's telescope located near Stuttgart, Germany, planet Earth [ http://science.nasa.gov/headlines/y2006/ 24mar_73p.htm?list237669 ]. The Ring Nebula (upper right) is more like 2,000 light-years distant, well within our own Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap050825.html ]. At a distance of 200 million light-years, IC 1296 (between comet and ring) is beyond even the Milky Way's boundaries. Because the comet is so close, it appears to move relatively rapidly against the distant stars. This dramatic telescopic view [ http://www.photomeeting.de/astromeeting/comets/ 060508SchwWas_a_d.htm ] was composited from two sets of images, one compensating [ http://www.ewellobservatory.com/ccd/ comet.cfm ] for the comet's apparent motion and one recording the background stars and nebulae [ http://antwrp.gsfc.nasa.gov/apod/ap030516.html ]. |
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Ceres: Asteroid or Planet?
| Title |
Ceres: Asteroid or Planet? |
| Explanation |
Is Ceres [ http://en.wikipedia.org/wiki/Ceres_%28asteroid%29 ] an asteroid [ http://www.nineplanets.org/asteroids.html ] or a planet? Although a trivial designation to some, the recent suggestion by the Planet Definition Committee [ http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_committee.html ] of the International Astronomical Union [ http://www.iau2006.org/mirror/www.iau.org/NEWS.55.0.html ] would have Ceres reclassified from asteroid to planet. A change in taxonomy might lead to more notoriety for the frequently overlooked world. Ceres [ http://www.pantheon.org/articles/c/ceres.html ], at about 1000 kilometers across, is the largest object in the main asteroid belt [ http://www.solstation.com/stars/asteroid.htm ] between Mars and Jupiter. Under the newly proposed criteria [ http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_release.html ], Ceres would qualify as a planet because it is nearly spherical and sufficiently distant from other planets. Pictured above [ http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/27/image/a ] is the best picture yet of Ceres, taken by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap010806.html ] as part of a series of exposures ending in 2004 January. Currently, NASA's Dawn mission [ http://dawn.jpl.nasa.gov/ ] is scheduled to launch in 2007 June to explore Ceres and Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap060820.html ], regardless of their future designations. |
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Comet SWAN Brightens
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Comet SWAN Brightens |
| Explanation |
A newly discovered comet has brightened enough to be visible this week with binoculars. The picturesque comet [ http://antwrp.gsfc.nasa.gov/apod/ap050904.html ] is already becoming a favored target for northern sky imagers. Pictured above [ http://www.astrostudio.at/Astrofotos/astrofotos.php?k_id=69 ] just last week, Comet SWAN showed a bright blue-green coma and an impressive tail. Comet C/2006 M4 (SWAN) [ http://cometography.com/lcomets/2006m4.html ] was discovered in June in public images from the Solar Wind Anisotropies [ http://www.fmi.fi/research_space/space_7.html ] (SWAN) instrument of NASA and ESA [ http://en.wikipedia.org/wiki/ESA ]'s Sun-orbiting SOHO [ http://sohowww.nascom.nasa.gov/ ] spacecraft. Comet [ http://en.wikipedia.org/wiki/Comet ] SWAN, near magnitude six, will be visible with binoculars in the northeastern sky not far from the Big Dipper over the next few days before dawn. The comet [ http://www.aerith.net/comet/catalog/2006M4/2006M4.html ] is expected to reach its peak brightness this week. Passing its closest to the Sun two days ago, Comet SWAN [ http://ssd.jpl.nasa.gov/sbdb.cgi?ID=dK06M040;orb=1;cov=0#orb ] and will be at its closest to the Earth toward the end of this month. Comet SWAN's unusual orbit [ http://cfa-www.harvard.edu/cfa/ps/mpec/K06/K06S89.html ] appears to be hyperbolic [ http://adsabs.harvard.edu/abs/1992A&A...259..692K ], meaning that it will likely go off into interstellar space [ http://antwrp.gsfc.nasa.gov/apod/ap020210.html ], never to return. |
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3D Mercury Transit
| Title |
3D Mercury Transit |
| Explanation |
Mercury is now [ http://www.astronomy.com/ASY/CS/forums/314872/ ShowPost.aspx ] visible shortly before dawn, the brightest "star" just above the eastern horizon. But almost two weeks ago Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap061114.html ] actually crossed the face of the Sun for the second time in the 21st century. Viewed with red/blue glasses [ http://photojournal.jpl.nasa.gov/Help/VendorList.html ], this stereo anaglyph combines space-based images of the Sun and innermost planet in a just-for-fun 3D [ http://www.sungazer.net/3dtransit.html ] presentation of the Mercury transit [ http://www.transitofvenus.org/mercury.htm ]. The solar disk image is from Hinode [ http://solarb.msfc.nasa.gov/index.html ]. (sounds like "hee-no-day", means sunrise). A sun-staring observatory, Hinode was launched from Uchinoura Space Center and viewed the transit [ http://solar-b.nao.ac.jp/news_e/20061109_e.shtml ] from Earth orbit. Superimposed on Mercury's dark silhouette is a detailed image [ http://antwrp.gsfc.nasa.gov/apod/ap011124.html ] of the planet's rugged surface based on data from the Mariner 10 [ http://nssdc.gsfc.nasa.gov/nmc/tmp/1973-085A.html ] probe that flew by Mercury in 1974 and 1975. |
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Comet McNaught Heads for the
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| Title |
Comet McNaught Heads for the Sun |
| Explanation |
Early morning risers with a clear and unobstructed eastern horizon can enjoy the sight of Comet McNaught (C/2006 P1) in dawn skies over the next few days. Discovered in August by R. H. McNaught (Siding Spring Survey [ http://www.mso.anu.edu.au/~rmn/ ]) the comet has grown bright enough to see with the unaided eye but will soon be lost in the glare of the Sun. Still, by January 11 sun-staring spacecraft SOHO should be able to offer web-based views [ http://sohowww.nascom.nasa.gov/data/realtime/c3/ 512/ ] as the comet heads toward [ http://neo.jpl.nasa.gov/cgi-bin/db_shm?name=c/2006+P1 ] a perihelion [ http://www.windows.ucar.edu/tour/ link=/physical_science/physics/mechanics/orbit/ perihelion_aphelion.html&edu=high ] passage inside the orbit of Mercury. This image captures [ http://www.astrostudio.at/Astrofotos/astrofotos.php?k_id=71 ] the new naked-eye comet [ http://www.nasa.gov/worldbook/comet_worldbook.html ] at about 2nd magnitude [ http://en.wikipedia.org/wiki/Apparent_magnitude ] in twilight skies near sunset on January 3rd. After rounding the Sun [ http://www.shadowandsubstance.com/ ] and emerging from the solar glare later this month, Comet McNaught [ http://www.aerith.net/comet/catalog/2006P1/2006P1.html ] could be even brighter. |
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Jupiter, Saturn and Messier
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| Title |
Jupiter, Saturn and Messier 45 |
| Explanation |
Brilliant Venus falls out [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html] of the evening sky as March ends, but Jupiter and Saturn remain well up above the western horizon. Jupiter [ http://www.jpl.nasa.gov/galileo/jupiter/jupiter.html ] blazes forth above and to the left of a slightly fainter Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap000212.html ] in this telephoto picture taken on January 19th. Near the top lies the lovely Pleiades [ http://antwrp.gsfc.nasa.gov/apod/ap000227.html ] star cluster with suggestions of its characteristic blue reflection nebulae [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/ apod_search?reflection+nebula ]. These planets and the Pleiades have a similar, easily recognizable orientation in the Spring night sky. Also known as M45 [ http://www.seds.org/messier/m/m045.html ], the 45th object in French astronomer Charles Messier's [ http://antwrp.gsfc.nasa.gov/apod/ap960626.html ] famous catalog, the Pleiades will likely soon be checked off many stargazers' tally lists. For northern hemisphere observers this weekend offers a prime opportunity to complete a Messier Marathon [ http://www.seds.org/messier/xtra/marathon/ marathon.html ] -- the viewing of all 110 Messier catalog objects [ http://www.seds.org/messier/data2.html ] in one glorious [ http://antwrp.gsfc.nasa.gov/apod/ap000311.html ] dusk to dawn observing run. This weekend it will also be possible to complete an all-planet marathon, observing all the solar system's [ http://space.jpl.nasa.gov/ ] planets in a single night. And if you still need something to look at, the International Space Station [ http://www.hq.nasa.gov/osf/station/viewing/ issvis.html ] could also be visible arcing through the skies depending on your location, but Mir will not [ http://www.russianspaceweb.com/ ]. |
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Jupiter, Vesta, and the Milk
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| Title |
Jupiter, Vesta, and the Milky Way |
| Explanation |
In this gorgeous skyscape, gas giant Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap070329.html ] along with the stars and cosmic dust clouds of the Milky Way [ http://antwrp.gsfc.nasa.gov/apod/ap070330.html ] hang over the southern horizon in the early morning hours as seen from Stagecoach, Colorado, USA. Recorded on Thursday, Jupiter is the brightest object near picture center. Along with the stunning Milky Way, Jupiter is hard to miss, but a careful inspection of the view also reveals main belt [ http://www.solstation.com/stars/asteroid.htm ] asteroid Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap060820.html ]. Of all the asteroids [ http://www.nineplanets.org/asteroids.html ] Vesta is the brightest and is now just bright enough to be visible to the naked eye from locations with very dark, clear skies. Vesta (as well as Jupiter) appears relatively bright now because it is near opposition, literally [ http://www.heavens-above.com/ gloss.asp?term=opposition ] opposite the Sun in planet Earth's sky and closest to Earth in its orbit. For Vesta [ http://dawn.jpl.nasa.gov/feature_stories/ Vesta_chart_descrip.asp ], this opposition offers the best viewing in many years. The year 2007 also coincides [ http://adsabs.harvard.edu/abs/1907Obs....30..103L ] with the 200th anniversary of the asteroid's discovery [ http://dawn.jpl.nasa.gov/DawnCommunity/ flashbacks/fb_06.asp ]. Starting late next month, NASA plans to launch the Dawn mission [ http://dawn.jpl.nasa.gov/index.asp ] intended to explore Vesta (and Ceres) and the main asteroid belt. |
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Small Worlds Ceres and Vesta
| Title |
Small Worlds Ceres and Vesta |
| Explanation |
Ceres [ http://www.planetary.org/explore/topics/asteroids_and_comets/ ceres.html ] and Vesta [ http://hubblesite.org/newscenter/archive/releases/ 1997/27 ] are, respectively, only around 950 kilometers and 530 kilometers in diameter - about the size of Texas and Arizona. But they are two of the largest of over 100,000 minor bodies [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ asteroidfact.html ] orbiting in the main asteroid belt [ http://www.solstation.com/stars/ asteroid.htm ] between Mars and Jupiter. These remarkably detailed Hubble Space Telescope images [ http://hubblesite.org/newscenter/archive/releases/ 2007/27/ ] show brightness and color variations across the surface of the two small worlds. The variations could represent large scale surface features or areas of different compositon. The Hubble image data will help astronomers plan for a visit by the asteroid-hopping Dawn spacecraft [ http://dawn.jpl.nasa.gov/index.asp ], scheduled for launch on July 7 and intended to orbit first Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap070525.html ] and then Ceres [ http://antwrp.gsfc.nasa.gov/apod/ap060821.html ] after a four year interplanetary cruise. Though Shakespeare [ http://www.phrases.org.uk/meanings/305250.html ] might not have been impressed, nomenclature introduced by the International Astronomical Union in 2006 classifies nearly spherical Ceres as a dwarf planet [ http://en.wikipedia.org/wiki/Dwarf_planet ]. |
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Zodiacal Light and the False
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| Title |
Zodiacal Light and the False Dawn |
| Explanation |
An unusual triangle of light will be particularly bright near the eastern horizon before sunrise during the next two months for observers in Earth's northern hemisphere. Once considered a false dawn [ http://www.odysseymagazine.com/pages/Stargazer.html ], this triangle of light is actually Zodiacal Light [ http://home.wanadoo.nl/marco.langbroek/zodiac.html ], light reflected from interplanetary dust particles [ http://antwrp.gsfc.nasa.gov/apod/ap010813.html ]. The triangle is clearly visible on the left of the above frame taken from Mauna Kea [ http://www.ifa.hawaii.edu/mko/ ] in Hawaii [ http://www.state.hi.us/ ] on August 30 by one of the developing global network of fisheye nighttime web cameras [ http://concam.net/ ] called CONCAMs [ http://concam.net/about.html ]. Zodiacal dust [ http://stardust.wustl.edu/IDPIntro.html ] orbits the Sun [ http://www.nineplanets.org/sol.html ] predominantly in the same plane as the planets: the ecliptic [ http://antwrp.gsfc.nasa.gov/apod/ap001014.html ]. Indeed, the triangle points to bright spots Jupiter and Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap010807.html ], with Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap010702.html ] nearer the center. Zodiacal light [ http://www.as.wvu.edu/~jel/skywatch/skw9810h.html ] is so bright this time of year because the dust band [ http://antwrp.gsfc.nasa.gov/apod/ap000517.html ] is oriented nearly vertical at sunrise, so that the thick air near the horizon does not block [ http://www.earthsky.com/2000/es000327.html ] out relatively bright reflecting [ http://sirtf.jpl.nasa.gov/SciUser/C_PropKit/bgdoc_release/node3.html ] dust. Zodiacal light [ http://antwrp.gsfc.nasa.gov/apod/ap990613.html ] is also bright for people in Earth's northern hemisphere in March and April just after sunset. |
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Dawn Launch Mosaic
| Title |
Dawn Launch Mosaic |
| Explanation |
Shortly after sunrise [ http://www.nasa.gov/mission_pages/dawn/news/ dawn-20070927a.html ] on Thursday at Cape Canaveral [ http://www.nps.gov/nr/travel/aviation/cap.htm ] Air Force Station, the Dawn spacecraft [ http://www.nasa.gov/mission_pages/dawn/spacecraft/index.html ] began its journey to the asteroid belt, arcing eastward into a blue and cloudy sky. Dawn's voyage began on a conventional, chemically fueled [ http://exploration.grc.nasa.gov/education/rocket/ combst1.html ] Delta II rocket [ http://exploration.grc.nasa.gov/education/rocket/ bgmr.html ], but will continue with an innovative ion propulsion system [ http://dawn.jpl.nasa.gov/mission/ion_engine_interactive/ index.html ]. The spacecraft's extremely efficient ion engines [ http://science.nasa.gov/headlines/y2000/ast15jun_1.htm ] will use electricity derived from solar power to ionize xenon atoms and generate a gentle but continuous thrust. After a four year interplanetary cruise, Dawn will orbit two small worlds [ http://antwrp.gsfc.nasa.gov/apod/ap070622.html ], first Vesta and then Ceres. Vesta is one of the largest main belt asteroids, while nomenclature introduced by the International Astronomical Union in 2006 classifies nearly spherical Ceres as a dwarf planet [ http://solarsystem.nasa.gov/planets/ profile.cfm?Object=Dwarf&Display=OverviewLong ]. |
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Comet Hale-Bopp Over Indian
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| Title |
Comet Hale-Bopp Over Indian Cove |
| Explanation |
Comet Hale-Bopp, the Great Comet of 1997 [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?great+comet+1997 ], was quite a sight. No comets [ http://www.nineplanets.org/comets.html ] of comparable brightness have graced the skies of Earth [ http://antwrp.gsfc.nasa.gov/apod/ap010204.html ] since then. During this next month, however, even besides the fleeting Comet Bradfield [ http://antwrp.gsfc.nasa.gov/apod/ap040419.html ], "two" comets have a slight chance of rivaling Hale-Bopp [ http://www2.jpl.nasa.gov/comet/ ] and a good chance of putting on a memorable [ http://antwrp.gsfc.nasa.gov/htmltest/gifcity/comet.html ] sky show. Unfortunately, most of the show will be confined to sky gazers in Earth's southern hemisphere [ http://antwrp.gsfc.nasa.gov/apod/ap021222.html ]. Both comets are already visible [ http://encke.jpl.nasa.gov/RecentObs.html#02T7 ] to the unaided eye from there. The first, Comet C/2002 T7 (LINEAR) [ http://cometography.com/lcomets/2002t7.html ], should be at its best before dawn during the first weeks of May from the south. The second, Comet C/2001 Q4 (NEAT) [ http://cometography.com/lcomets/2001q4.html ], should be visible in early May from all over the Earth. Both comets [ http://www.space.com/spacewatch/comet_double_040319.html ] appear to be approaching [ http://skyandtelescope.com/observing/objects/comets/article_1037_1.asp ] the inner Solar System [ http://www.nineplanets.org/overview.html ] for the first time and so it is very hard to predict [ http://www.exploratorium.edu/exploring/space/kohoutek.html ] how bright each will become. In the above photograph [ http://www2.jpl.nasa.gov/comet/pach17.html ] taken 1997 April 6, Comet Hale-Bopp was imaged from the Indian Cove Campground in the Joshua Tree National Forest [ http://www.nps.gov/jotr/ ] in California [ http://www.state.ca.us/ ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ]. A flashlight [ http://www.geocities.com/~stuarts1031/flashlight.html ] was used to momentarily illuminate foreground rocks during this six minute exposure. |
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Comet C/2002 T7 (LINEAR)
| Title |
Comet C/2002 T7 (LINEAR) |
| Explanation |
Discovered by the the Lincoln Near Earth Asteroid Research (LINEAR) project in October of 2002, comet C/2002 T7 [ http://antwrp.gsfc.nasa.gov/apod/ap040209.html ] is now visiting the inner solar system, making its closest approach (see animation by L. Koehn [ mailto:zeromagnitude@aol.com ]) to the Sun tomorrow, April 23rd. Emerging from the solar glare, the comet is [ http://www.nineplanets.org/comets.html ] now just visible to the unaided eye in the constellation Pisces, near the eastern horizon in morning twilight. In this gorgeous telescopic view [ http://www.noao.edu/outreach/aop/observers/ c-2002t7.html ] recorded before dawn yesterday, the clearly active comet has developed an extensive, complex tail extending [ http://antwrp.gsfc.nasa.gov/apod/ap000413.html ] over 2 degrees in the anti-sunward direction, and a pronounced anti-tail [ http://encke.jpl.nasa.gov/define.html ] or anomalous tail. Later next month this comet should appear brighter, making its closest approach to planet Earth on May 19th. In fact, it could share southern skies [ http://skyandtelescope.com/observing/objects/comets/ article_1037_1.asp ] with another naked-eye comet, also anticipated to brighten in May, designated C/2001 Q4 (NEAT). |
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Bright Leonids
| Title |
Bright Leonids |
| Explanation |
Rich in bright and awesome [ http://antwrp.gsfc.nasa.gov/apod/ap981113.html ] fireballs [ http://science.nasa.gov/newhome/headlines/ast18nov98_1.htm ], the Leonid Meteor Shower [ http://www.skypub.com/sights/meteors/leonids/king.html ] came early this year. In fact, judging from meteor watcher reports [ http://www.skypub.com/sights/meteors/leonids/98firstreports.html ] the peak came nearly 15 hours earlier than the best predictions [ http://ssd.jpl.nasa.gov/leonids.html ]. Observers on the Canary Islands [ http://antwrp.gsfc.nasa.gov/apod/ap980305.html ] were probably close to an ideal viewing location and recorded a maximum of effectively about 200 to 250 meteors per hour near dawn on November 17 - way below the peak rate during the 1966 Leonid meteor storm display [ http://www-space.arc.nasa.gov/~leonid/1966.html ]. Still, those blessed with clear skies in dark, early morning hours all over planet Earth were treated to a first rate cosmic light show [ http://www.leonidslive.com/ ]. Roving astrophotographer Olivier Staiger took this stunning image [ http://eclipse.span.ch/17nov98.htm ] of two bright Leonids in the skies over Chiang Mai, Thailand [ http://thaiastro.nectec.or.th/eng/index.html ]. |
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Moon, Planets, and Rocket Tr
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| Title |
Moon, Planets, and Rocket Trails |
| Explanation |
Are you an early riser [ http://redfrog.norconnect.no/~poems/poems/09560.html ]? Over the last month or so, the bright planets [ http://antwrp.gsfc.nasa.gov/apod/ap990325.html ] Jupiter and Saturn have come to adorn eastern skies before sunrise [ http://redfrog.norconnect.no/~poems/poems/17572.html ]. In fact, astrophotographer Joe Orman [ http://home.cwix.com/~pam.orman@cwix.com/JoeGallery.html ] anticipated that an early bird's reward for looking east on June 10 would be this pleasing arrangement of Jupiter (top right), a crescent Moon, and Saturn (near center), but he was surprised to also find these eerie, iridescent clouds wafting through the pre-dawn sky over suburban Phoenix, Arizona, USA. The clouds turned out to be rocket [ http://www-istp.gsfc.nasa.gov/stargaze/Srockhis.htm ] engine [ http://www.wff.nasa.gov/ ] trails [ ftp://pao.gsfc.nasa.gov/pub/PAO/Releases/1999/W99-013.htm ] from defense missile tests at the range in White Sands [ http://ruidoso.net/chamber/outdoors/whitesan.html ], New Mexico ... about 300 miles away. While the Moon's phase [ http://aa.usno.navy.mil/AA/data/docs/MoonPhase.html#ninetynine ] is just past new moon [ http://lunar.arc.nasa.gov/history/mythologyh.html ], gone now from the pre-dawn horizon, brilliant Jupiter [ http://galileo.ivv.nasa.gov/ ] and Saturn [ http://www.jpl.nasa.gov/cassini/ ] can still be seen high toward the southeast in the constellation [ http://www.astro.wisc.edu/~dolan/constellations/extra/ constellations.html ] Aries. |
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Phoebe Temperature Maps
PIA06403
Saturn
Composite Infrared Spectrome
…
| Title |
Phoebe Temperature Maps |
| Original Caption Released with Image |
A montage of maps of Saturn's moon Phoebe shows surface temperatures at various times of day as determined by the composite infrared spectrometer onboard Cassini during the June 11, 2004, Phoebe flyby. The asterisk on each map shows the location of the subsolar point, where the Sun is directly overhead. This point moves across the surface as Phoebe rotates. It is morning in regions to the left of the subsolar point, and afternoon in regions to the right. Like a newspaper weather map, different colors indicate different temperatures, though Phoebe's temperatures are distinctly cooler than even the coldest January day on Earth. Equatorial temperatures peak in the early afternoon near 112 Kelvin (-257 Fahrenheit), plunging to 78 Kelvin (-319 Fahrenheit) before dawn, and are even colder at higher latitudes. The large day/night temperature contrasts imply that Phoebe's surface is covered in loose dust or ice particles that store little heat and thus cool off rapidly at night. Regions of Phoebe's surface that were not observed are shown in black. Most of the maps show the effect on surface temperatures of the large crater-like depression seen in Cassini's visible-wavelength images of Phoebe, which is located just left of center in these maps. Crater walls that are shadowed and cold in the early morning in the first map are sunlit and warm in the late afternoon in the final map. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov [ http://saturn.jpl.nasa.gov/ ] and the Cassini imaging team home page, http//cirs.gsfc.nasa.gov/ [ http://cirs.gsfc.nasa.gov/ ]. |
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Phoebe's Radiation
PIA06402
Saturn
Composite Infrared Spectrome
…
| Title |
Phoebe's Radiation |
| Original Caption Released with Image |
This image shows thermal radiation from the day and night sides of Saturn's moon Phoebe, taken by the composite infrared spectrometer onboard Cassini 1.8 hours before the spacecraft's closest approach to Phoebe on June 11, 2004. The left-hand panel displays the image in grayscale format, showing the brightness of Phoebe's radiation in the wavelength range 15-17 microns, which is about 25 times the longest wavelength visible to the naked eye. In the middle panel this brightness is used to estimate the surface temperature distribution across Phoebe. Temperatures are given in degrees Kelvin, and vary from a relatively toasty 107 Kelvin (-267 Fahrenheit), in the late morning near the equator (white, lower right), to less than 75 Kelvin (-324 Fahrenheit) in the northern hemisphere in the pre-dawn hours (dark blue, upper left). The "ragged edge" of Phoebe in this region is an instrumental artifact. Temperatures are affected strongly by topography, as can be seen by comparison with the visible-wavelength image (right). Some of the coldest temperatures are found in the shadowed region inside the large depression in the northern hemisphere (upper right). The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov [ http://saturn.jpl.nasa.gov/ ] and the Cassini imaging team home page, http//cirs.gsfc.nasa.gov/ [ http://cirs.gsfc.nasa.gov/ ]. |
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MGS MOC Coverage of Mars Pol
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PIA02310
Sol (our sun)
Mars Orbiter Camera
| Title |
MGS MOC Coverage of Mars Polar Lander Region |
| Original Caption Released with Image |
. The selection criteria were to find a place that was relatively flat and relatively smooth, but which displayed characteristics of the south polar layered materials. The inset (upper left) shows the location of the landing zone with respect to the south polar residual (year-round) ice cap. The base map used here is a mosaic of Viking Orbiter images from the U.S. Geological Survey. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO., High-resolution views of the Mars Polar Lander [ http://www.marspolarlander.com/ ] landing zone were essential to the selection of a safe place for the December 3, 1999, landing to occur. The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) took its first pictures of the landing zone in December 1997 [ http://www.msss.com/mars_images/3_9_98_release/7200/index.html ] and January 1998 [ http://www.msss.com/mars_images/3_9_98_release/9500/index.html ]. After that time, the south polar region was not accessible to the camera until June 1999, when the south polar winter was ending and the sun began to dawn on this region once again. Since the beginning of June 1999, an intense period of imaging has been conducted over the landing zone so that a safe site could be found. The final site has now been identified, and the pictures shown here give some idea of what the Mars Polar Lander will encounter a little more than three months from now. This figure shows the zone originally proposed by the Mars Volatiles and Climate Surveyor (MVACS) [ http://mvacs.ess.ucla.edu/ ] science team for the Mars Polar Lander mission, which spanned the region from 72° to 78°S latitude and 170° to 230°W longitude. The thin white boxes and lines crossing the proposed zone outline MOC images taken between the first week in June 1999 and the first week in August 1999. The longest images were taken at 12 by 18 meters (39 by 59 feet) per pixel, there are three sets of long images, each taken during a given week in June as the terminator (the line separating "night" from "day") moved south across the landing zone. Smaller swaths represent images at higher resolution. The best resolution so far achieved is about 4 meters (13 ft) per pixel, better images will be taken in September and October as the sun rises farther and the surface becomes better illuminated. This figure shows the location of the primary (blue) and secondary (white) landing ellipses, which were selected on the basis of interpretation of the MGS data, in particular data from the Mars Orbiter Laser Altimeter [ http://ltpwww.gsfc.nasa.gov/tharsis/98lander.html ] and the Mars Orbiter Camera [ http://www.msss.com/mars_images/index.html ] |
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Martian Sunrise at Utopia Pl
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PIA00576
Sol (our sun)
Camera 2
| Title |
Martian Sunrise at Utopia Planitia |
| Original Caption Released with Image |
A Martian sunrise was captured in this Viking 2 Lander picture taken June 14, 1978, at the spacecraft's Utopia Planitia landing site. The data composing this image were acquired just as the Sun peaked over the horizon on the Lander's 631st sol (Martian solar day). Pictures taken at dawn (or dusk) are quite dark except where the sky is brightened above the Sun's position. The glow in the sky results as light from the Sun is scattered and preferentially absorbed by tiny particles of dust and ice in the atmosphere. When the Viking cameras are calibrated for darker scenes, the "sky glow" tends to saturate their sensitivity and produce the bright regions seen here. The "banding" and color separation effects are also artifacts, rather than real features, and are introduced because the cameras are not able to record continuous gradations of light. The cameras must represent such gradations in steps (bands) of brightness and color, and the process sometimes produces some "false" colors within the bands. The scattering of light closest to the Sun's position tends to enhance blue wavelengths. The narrowing sky glow nearer the horizon above the Sun's position occurs as a result of light extinction. At that elevation, the optical path of sunlight through the atmosphere is at its longest penetration angle, and a substantial portion of the light is simply prevented from reaching the cameras by the dust, ice particles and other material in its way. NASA's Langley Research Center was the primary and extended mission manager, JPL assumed management for continued mission operations. |
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