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Earth and Moon and Crater of Goddard Space Flight Center (GSFC)
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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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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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NASA's Hubble Looks for Poss
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NASA's Hubble Looks for Possible Moon Resources |
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Hubble Space Telescope Looks
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Hubble Space Telescope Looks at the Moon to Prospect for Resources (Aristarchus Crater - gray) |
| Abstract |
My edit: The Hubble Space Telescope was used to gather high resolution multi spectral data of the moon's Aristarchus Crater in order to investigate the possibility of potential oxygen producing minerals on the surface. Identifying such minerals could aid in planning future sustained human missions on the moon. Initial analysis of the data indicate the likely presence of titanium and iron oxides. Both these minerals could be used as oxygen sources essential for human exploration. This visualization starts with a view of the moon as seen from Earth using a USGS Apollo derived artist rendered texture (airbrushed). The camera then zooms into the Aristarchus Crater region. Simulated topography derived from Clementine data is used for relief and high resolution HST data is used for the area of interest. After investigating Aristarchus Crater, the camera then moves over to Schroter's Valley for a brief investigation. This visualization is match rendered with id 3275 so that the color version can be dissolved in or out as needed. Exposure Time: 2.5 minutes Filters: F250W (250nm), F344N (344nm), F502N (502nm), F658N (658nm) |
| Completed |
2005-10-12 |
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Hubble Space Telescope Looks
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Hubble Space Telescope Looks at the Moon to Prospect for Resources (Aristarchus Crater - color) |
| Abstract |
The Hubble Space Telescope looked at specific areas of the moon prospecting for important minerals that may aid future sustained human presence on the moon. Initial analysis of the data indicate the likely presence of titanium and iron oxides. These minerals can be sources of oxygen, essential for human exploration. This visualization starts with a view of the moon as seen from Earth using a USGS Apollo derived artist rendered texture (airbrushed). The camera then zooms into the Aristarchus crater region. Clementine derived cimulated topography is shown around the outside and HST color imagery is shown filling most of the view. The camera then flys into the crater site using using simulated topgraphy and then over to Schroter's Valley. This visualization is match rendered with id 3274 so that the color version can be dissolved in or out as needed. The colors are from these HST filter bands: RED = 502/250 nm ratio, GREEN = 502 nm (green), BLUE = 250/502 nm ratio In the image, blues are in principle higher in ilmenite. |
| Completed |
2005-10-12 |
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Hubble Space Telescope Looks
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| Title |
Hubble Space Telescope Looks at the Moon to Prospect for Resources (Aristarchus Crater - color) |
| Abstract |
The Hubble Space Telescope looked at specific areas of the moon prospecting for important minerals that may aid future sustained human presence on the moon. Initial analysis of the data indicate the likely presence of titanium and iron oxides. These minerals can be sources of oxygen, essential for human exploration. This visualization starts with a view of the moon as seen from Earth using a USGS Apollo derived artist rendered texture (airbrushed). The camera then zooms into the Aristarchus crater region. Clementine derived cimulated topography is shown around the outside and HST color imagery is shown filling most of the view. The camera then flys into the crater site using using simulated topgraphy and then over to Schroter's Valley. This visualization is match rendered with id 3274 so that the color version can be dissolved in or out as needed. The colors are from these HST filter bands: RED = 502/250 nm ratio, GREEN = 502 nm (green), BLUE = 250/502 nm ratio In the image, blues are in principle higher in ilmenite. |
| Completed |
2005-10-12 |
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Multiple Views of the Moon
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Multiple Views of the Moon |
| Description |
On April 14, 2003, a special maneuver of the Terra [ http://terra.nasa.gov/ ] spacecraft was performed as it traversed the nightside of orbit 17672. This maneuver entailed a "backward somersault" of the spacecraft as it pitched end-over-end, allowing the normally Earth-viewing instruments to look at deep space and the waxing gibbous Moon. The purpose of this acrobatic feat is to assist in the calibration of several of Terra's instruments. Over a 16-minute interval, the lunar disk passed through the fields-of-view of all nine MISR cameras, resulting in this unique set of images. Shown here are "raw" red-band data, with no adjustments for radiometric calibration. Because the pitch rate of the spacecraft resulted in different pixel spacings in the left-right and up-down directions, the aspect ratios of the raw images have been adjusted to provide roughly circular disks. Each image is labeled with the name of the camera which acquired it. The "D" cameras are the ones which normally view the Earth at the most oblique angles, and the letters "f" and "a" denote fore- and aft-viewing orientations, respectively. "An" is the vertical-viewing (nadir) camera. Why are the "D" images the sharpest? The letters "A", "B", "C", and "D" refer to the different lens designs used on MISR, with the "D" lenses having focal lengths more than twice as large as the "A" lenses. A pixel at the center of the lunar disk subtends about 65 kilometers for the "D" cameras and about 137 kilometers for the "A" cameras. As the Moon passed into the field-of-view of each of the nine cameras, the lunar disk was always viewed "straight on", so there is no multiangular effect in these images. Familiar lunar features are clearly recognizable. The dark lunar "maria" are vast plains of basaltic lava. The feature near the upper right-hand edge of the lunar disk is Mare Crisium. Between it and image center is Mare Tranquillitatis, site of the 1969 Apollo 11 lunar landing. About halfway between image center and the left edge of the disk is the crater Copernicus, with the large Mare Imbrium to its north. Near the bottom is the crater Tycho, with bright rays of ejecta extending in many directions. Planning for this maneuver has been underway since before Terra's launch. A high school Applied Engineering Competition [ http://terra.nasa.gov/Events/Competition/ ] was also held (in partnership with the Goddard Space Flight Center's Educational Programs Office) in which students were asked to visualize the precise timing and mechanics of Terra's on-orbit calibration maneuvers. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://www-misr.jpl.nasa.gov/ ] Text by David J. Diner (JPL) and Clare Averill (Acro Service Corporation/JPL). |
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Eros From Orbit
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Eros From Orbit |
| Explanation |
On February 14th, the NEAR spacecraft [ http://near.jhuapl.edu/NEAR/ ] became the first artificial moon of an asteroid [ http://antwrp.gsfc.nasa.gov/apod/ap991014.html ]. Captured by the gentle gravity of a 20 mile long slipper-shaped [ http://near.jhuapl.edu/NEAR/iod/20000214b/index.html ] mountain of rock, NEAR recorded this premier image [ http://near.jhuapl.edu/NEAR/iod/20000214g/index.html ] while orbiting asteroid 433 Eros at a distance of about 200 miles. The image shows features as small as 100 feet across in a view dominated by a 3 mile wide crater near Eros' narrow waist. Enticing [ http://near.jhuapl.edu/NEAR/news/sci_updates/00feb15.html ] layers and grooves are visible within the crater rim along with an enormous 170 foot boulder lying on the crater floor (near picture center). Although Eros is a large S-type near-earth asteroid [ http://www.seds.org/nineplanets/nineplanets/asteroids.html ], it is still not massive enough for its own gravity to have shaped it into a planet-like [ http://oposite.stsci.edu/pubinfo/pr/95/20.html ] spherical form. By comparison [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html ], Eros has less than a thousandth Earth's gravity, so a 100 pound object on Earth would weigh about 1 "ounce" on Eros. A baseball thrown at 22 miles per hour would completely escape into space. The weak gravity and irregular shape make orbiting Eros a delicate challenge for NEAR's [ http://near.jhuapl.edu/NEAR/intro/faq.html ] controllers who plan a year long exploration program with possible close approaches to the asteroid's surface [ http://near.jhuapl.edu/NEAR/iod/20000215/index.html ]. |
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Nearer To Asteroid Eros
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Nearer To Asteroid Eros |
| Explanation |
As the robot spacecraft NEAR [ http://near.jhuapl.edu/spacecraft/ ] lowers itself toward asteroid 433 Eros [ http://near.jhuapl.edu/eros/ ], more surface details are becoming visible. Last week's maneuvers [ http://near.jhuapl.edu/NEAR/news/flash/00mar02_1b.html ] brought NEAR [ http://near.jhuapl.edu/intro/faq.html ] to within 204 kilometers of the floating mountain's surface [ http://antwrp.gsfc.nasa.gov/apod/ap000216.html ]. With increased resolution, NEAR's camera [ http://near.jhuapl.edu/NEAR/iod/archive.html ] then documented Eros' unusual shape [ http://antwrp.gsfc.nasa.gov/apod/ap000210.html ], craters [ http://antwrp.gsfc.nasa.gov/apod/ap990711.html ] large and small, boulders [ http://antwrp.gsfc.nasa.gov/apod/ap970905.html ], and mysterious grooves similar to asteroid Gaspra [ http://antwrp.gsfc.nasa.gov/apod/ap980712.html ] and Martian moon Phobos [ http://antwrp.gsfc.nasa.gov/apod/ap980914.html ]. If you could stand on Eros [ http://near.jhuapl.edu/eros/sum.html ], you would still be too small to be visible on this recent image [ http://near.jhuapl.edu/NEAR/iod/20000306/index.html ], which shows features as small as 20 meters across. However, you would feel gravity only 1/1000 that on Earth [ http://near.jhuapl.edu/news/flash/00feb15_2.html ], so that you could easily jump over even this large 5 kilometer wide crater. |
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Apollo 16: Exploring Plum Cr
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Apollo 16: Exploring Plum Crater |
| Explanation |
Apollo 16 [ http://www.nasm.edu/APOLLO/AS16/Apollo16_fact.html ] spent three days on Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/moon.html ] in April 1972. The fifth lunar landing mission [ http://www.ksc.nasa.gov/history/apollo/apollo-16/apollo-16.html ] out of six, Apollo 16 [ http://www.hq.nasa.gov/alsj/a16/a16j.html ] was famous for deploying and using an ultraviolet telescope as the first lunar observatory [ http://antwrp.gsfc.nasa.gov/apod/ap960608.html ], and for collecting rocks and data on the mysterious lunar highlands [ http://www.nasm.edu/APOLLO/AS16/Apollo16_MissionObj.html ]. In the above picture, astronaut John W. Young [ http://www.ksc.nasa.gov/persons/astronauts/u-to-z/YoungJW.txt ] photographs Charles M. Duke, Jr. [ http://nauts.com/astro/duke/duke.html ] collecting rock samples [ http://www.nasm.edu/apollo/apollotop10.htm ] at the Descartes landing site [ http://www.nasm.edu/APOLLO/AS16/Apollo16_LandingSite.html ]. Duke stands by Plum Crater while the Lunar Roving Vehicle [ http://antwrp.gsfc.nasa.gov/apod/ap990501.html ] waits parked in the background. The Lunar Roving Vehicle [ http://www.nasm.edu/apollo/lrv/lrv.htm ] allowed the astronauts to travel great distances to investigate surface features and collect rocks. High above, Thomas K. Mattingly orbits in the Command Module. |
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Ancient Craters on Saturn's
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Ancient Craters on Saturn's Rhea |
| Explanation |
Saturn's ragged moon Rhea has one of the oldest surfaces known. Estimated as changing little in the past billion years, Rhea [ http://en.wikipedia.org/wiki/Rhea_%28moon%29 ] shows craters [ http://en.wikipedia.org/wiki/Impact_crater ] so old they no longer appear round ? their edges have become compromised by more recent cratering. Like Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap051113.html ], Rhea's rotation is locked on Saturn, and the above image [ http://photojournal.jpl.nasa.gov/catalog/PIA08173 ] shows part of Rhea's surface [ http://antwrp.gsfc.nasa.gov/apod/ap051213.html ] that always faces Saturn. Rhea's leading surface is more highly cratered than its trailing surface. Rhea [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?rhea ] is composed mostly of water-ice but is thought to have a small rocky core. The above image [ http://photojournal.jpl.nasa.gov/catalog/PIA08173 ] was taken by the robot Cassini spacecraft [ http://www.esa.int/esaMI/Cassini-Huygens/SEM9D2HHZTD_0.html ] now orbiting Saturn. Cassini swooped past Rhea two months ago and captured the above image from about 100,000 kilometers away. Rhea [ http://www.nineplanets.org/rhea.html ] spans 1,500 kilometers making it Saturn's second largest moon after Titan [ http://antwrp.gsfc.nasa.gov/apod/ap060215.html ]. Several surface features on Rhea [ http://antwrp.gsfc.nasa.gov/apod/ap050215.html ] remain unexplained including large light patch [ http://antwrp.gsfc.nasa.gov/apod/ap050530.html ]es. |
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Crater On Ice
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Crater On Ice |
| Explanation |
Impact craters are common on Earth's moon [ http://antwrp.gsfc.nasa.gov/apod/ap990326.html ] but on Jupiter's large ice moon Europa [ http://sse.jpl.nasa.gov/features/planets/jupiter/ europa.html ], they are very rare. Over time, both bodies have been subjected to an intense pounding [ http://antwrp.gsfc.nasa.gov/apod/ap990610.html ] by the solar system's formative debris [ http://www.jhuapl.edu/public/pr/000530.htm ], but geological activity on Europa's surface seems to have erased most of these impact scars. This false-color infrared image [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA02561 ] from the Galileo spacecraft's NIMS instrument [ http://jumpy.igpp.ucla.edu/~nims/ ] shows a newly discovered crater on Europa as a light red ring feature near center surrounding a dark core. For scale, the dark core is about 29 kilometers in diameter. Only seven comparably [ http://antwrp.gsfc.nasa.gov/apod/ap970417.html ] large craters have now been identified on Europa's surface. Red colors in the image represent a relatively pure water ice [ http://www.glacier.rice.edu/invitation/1_icetypes.html ] composition while blue colors indicate that other minerals are present. The crater's central dark area may contain the remnants of the impacting body. The icy crust of Europa [ http://galileo.jpl.nasa.gov/moons/europa.html ] is of great interest, as evidence mounts [ http://galileo.jpl.nasa.gov/news/release/ press000110.html ] that it covers an ocean of liquid water, possibly providing suitable conditions for life. |
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Lingering Lunar Eclipse
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Lingering Lunar Eclipse |
| Explanation |
As the Moon passed almost directly through the center of Earth's shadow on July 16th, sky gazers [ http://www.live-eclipse.org/eclipse/lunar00/index.html ] in the Pacific hemisphere [ http://www.skypub.com/sights/eclipses/ 0007threeeclipses.shtml ] were graced by a lingering lunar eclipse [ http://sunearth.gsfc.nasa.gov/eclipse/extra/ TLE2000Jul16.html ]. The total phase lasted 1 hour and 47 minutes, the longest since 1859. A longer total lunar eclipse [ http://www.MrEclipse.com/Special/ LEprimer.html ] won't occur until the year 3000. Taking advantage of the lengthy totality [ http://www.rasnz.org.nz/Events2000.htm#Eclipse ], astronomer and photographer, Noel Munford used a small telescope to record this colourful picture of the eclipsed Moon [ http://antwrp.gsfc.nasa.gov/apod/ap960403.html ] and nearby stars in the skies above Palmerston North, New Zealand [ http://www.rasnz.org.nz/index.htm ]. Near the top in this southern hemisphere [ http://members.netro.com.au/~michael/astro/polar.htm ] perspective is the 84 kilometer wide bright ray crater Tycho. The Moon looks red even when it lies completely in shadow because it is still illuminated by sunlight reddened by dust and refracted by the atmosphere along the Earth's limb. Changes in atmospheric dust content mean that each eclipse [ http://eclipse99.ksc.nasa.gov/pages/ traditions.html ] can have a different appearance. An experienced observer, Munford comments that at mid totality this eclipse had a more uniform, delicate, subtle colour and was one of the lightest he has seen. |
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Full Moon Crossing
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Full Moon Crossing |
| Explanation |
On October 6th, a nearly full perigee [ http://antwrp.gsfc.nasa.gov/apod/ap041021.html ] Moon shone in Earth's night sky. The bright moonlight [ http://science.nasa.gov/headlines/y2006/ 28sep_strangemoonlight.htm ], accurate planning, and proper equipment resulted in this amazing composite [ http://pictures.ed-morana.com/ISSTransits/ ] featuring sharp silhouettes of the International Space Station (ISS) as it rapidly crossed (right to left) in front [ http://antwrp.gsfc.nasa.gov/apod/ap060921.html ] of the lunar disk. The picture was constructed using six video frames recorded from a site just outside Tracy, California, USA. Sporting newly deployed solar arrays, the ISS [ http://antwrp.gsfc.nasa.gov/apod/ap060920.html ] was at a range of about 260 miles from the telescope/video camera setup. In the background, about a thousand times more distant than the ISS, lies bright lunar ray crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap050305.html ]. |
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Degas Ray Crater on Mercury
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Degas Ray Crater on Mercury |
| Explanation |
Like the Earth's Moon, Mercury is [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html ] scarred with craters testifying to an intense bombardment during the early history [ http://antwrp.gsfc.nasa.gov/apod/ap990326.html ] of the Solar System. In 1974, the Mariner 10 [ http://pds.jpl.nasa.gov/planets/welcome/m10.htm ] spacecraft surveyed this innermost planet [ http://nssdc.gsfc.nasa.gov/imgcat/html/mission_page/ MC_Mariner_10_page1.html ] up close, producing the only detailed images of its tortured surface. In the above mosaic [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/ m10_aom_3_e.html ] the bright rays emanating from the 45 kilometer wide Degas crater almost appear to be painted on [ http://sunsite.unc.edu/wm/paint/auth/degas/ ]. The rays consist of light colored material blasted out during the crater's formation. Craters [ http://www.lpi.usra.edu/expmoon/science/ craterstructure.html ] older than Degas are covered by the ray material while younger craters are seen superimposed on the rays. Mercury's [ http://www.seds.org/nineplanets/nineplanets/ mercury.html ] gravity and density are about [ http://www.whfreeman.com/ENVIRONMENTALGEOLOGY/EXMOD36/ PLANET.HTM ] twice that of Earth's [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ planet_table_ratio.html ] Moon so such bright ray craters [ http://www.sunlink.net/~torff/bwlunar10.html ] on the lunar surface tend to be much larger. NASA plans to launch MESSENGER [ http://sd-www.jhuapl.edu/ MESSENGER/ ] to the least explored [ http://www.soest.hawaii.edu/PSRdiscoveries/Jan97/ MercuryUnveiled.html ] terrestrial planet in 2004. |
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Eclipsed Moon and Stars
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Eclipsed Moon and Stars |
| Explanation |
This dramatic image [ http://panther-observatory.com/gallery/moon/doc/ Mofi_03032007_cass.htm ] features a dark red Moon during a total lunar eclipse -- celestial shadow play [ http://antwrp.gsfc.nasa.gov/apod/ap060909.html ] enjoyed by many denizens of planet Earth [ http://spaceweather.com/eclipses/gallery_03mar07.htm ] last Saturday. Recorded near Wildon, Austria, the picture is a composite of two exposures, a relatively short exposure to feature the lunar surface and a longer exposure to capture background stars in the constellation Leo [ http://www.seds.org/Maps/Stars_en/Fig/leo.html ]. Completely immersed in Earth's cone-shaped shadow during the total eclipse [ http://www.inconstantmoon.com/cyc_ecl1.htm ] phase, the lunar surface is still illuminated by sunlight, reddened and [ http://antwrp.gsfc.nasa.gov/apod/ap031121.html ] refracted into the dark shadow region by a dusty atmosphere. As a result, familiar [ http://antwrp.gsfc.nasa.gov/apod/ap031212.html ] details of the Moon's nearside are easy to pick out, including the smooth lunar mare and the large ray crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap050305.html ]. In this telescopic view, the background stars are faint and most would be invisible to the naked eye. |
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Moon Mare and Montes
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Moon Mare and Montes |
| Explanation |
This arresting [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ] image of the third quarter moon in the excellent skies above the Pine Crest Farm Observatory, Dell Prairie, Wisconsin, was recorded [ http://www.scancam.com/ ] with a 24 inch telescope and digital camera on October 19. Marvelously detailed [ http://www.seds.org/billa/psc/lunam.html ], especially along the terminator or shadow line between lunar night [ http://antwrp.gsfc.nasa.gov/apod/ap960919.html ] and day, this cropped version of the full mosaicked image shows the cratered north polar region (top) and the broad smooth Mare Imbrium [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/lunar/ mare/mlm.html ]. Notable at the northern edge [ http://www.arval.org.ve/MoonMapen.htm ] of the Mare Imbrium (Sea of Rains) is the 95 kilometer wide dark crater Plato, while the dramatic straight "cut" to the right of Plato, (toward the terminator) is the Vallis Alpes (Alpine Valley). The long, graceful arc of the lunar [ http://www.tiac.net/users/richarde/ ] Montes Apenninus (Apennine Mountains) in the lower portion of the image sweeps southward along the boundary of the mare toward the left and ends near the bright ray crater [ http://antwrp.gsfc.nasa.gov/apod/ap001216.html ] Copernicus [ http://cass.jsc.nasa.gov/expmoon/orbiter/ orbiter-craters.html#COPER ] at the picture's edge. In 1971, Apollo 15 [ http://www.hq.nasa.gov/alsj/a15/a15j.html ] landed near the gap beyond the opposite (northern) end of the Montes Apenninus arc. |
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A Spherule from the Earth's
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A Spherule from the Earth's Moon |
| Explanation |
How did this spherule come to be on the Moon? When a meteorite [ http://www.nineplanets.org/meteorites.html ] strikes the Moon [ http://antwrp.gsfc.nasa.gov/apod/moon.html ], the energy of the impact [ http://science.nasa.gov/headlines/y2001/ast30nov_1.htm ] melts some of the splattering rock [ http://www.teachersource.com/micrometeorites.htm ], a fraction of which might cool into tiny glass beads [ http://antwrp.gsfc.nasa.gov/apod/ap010523.html ]. Many of these glass beads [ http://www.geocities.com/ladysveva/BeadHistory.html ] were present in lunar soil samples [ http://www.lpi.usra.edu/expmoon/Apollo17/A17_sampact.html ] returned to Earth by the Apollo missions [ http://www.nasm.si.edu/collections/imagery/apollo/apollo.htm ]. Pictured above [ http://www.lbl.gov/Science-Articles/Archive/lunar-spherule.html ] is one such glass spherule [ http://www.thefreedictionary.com/spherule ] that measures only a quarter of a millimeter [ http://lamar.colostate.edu/~hillger/everyday.htm ] across. This spherule [ http://antwrp.gsfc.nasa.gov/apod/ap040210.html ] is particularly interesting because it has been victim to an even smaller impact. A miniature crater [ http://antwrp.gsfc.nasa.gov/apod/ap990711.html ] is visible on the upper left, surrounded by a fragmented area caused by the shockwaves [ http://antwrp.gsfc.nasa.gov/apod/ap010623.html ] of the small impact. By dating [ http://www.gpc.edu/~pgore/geology/geo102/radio.htm ] many of these impacts [ http://www.sciencenews.org/20000311/fob3.asp ], astronomers can estimate [ http://www.lbl.gov/Science-Articles/Archive/lunar-spherule.html ] the history of cratering [ http://antwrp.gsfc.nasa.gov/apod/ap010428.html ] on our Moon. |
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Crater Copernicus
| Title |
Crater Copernicus |
| Explanation |
One of the more prominent craters [ http://antwrp.gsfc.nasa.gov/apod/ap990711.html ] on the Moon [ http://www.nineplanets.org/luna.html ] is named Copernicus [ http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Copernicus.html ]. Copernicus [ http://cass.jsc.nasa.gov/expmoon/orbiter/orbiter-craters.html#COPER ] is a large young crater visible with binoculars slightly northwest of the center of the Moon's Earth-facing hemisphere [ http://antwrp.gsfc.nasa.gov/apod/ap010218.html ]. Copernicus [ http://www.hawastsoc.org/solar/cap/moon/coper.htm ] is distinguished by its size and by the many bright rays pointing out from it. Although Copernicus [ http://www.mhhe.com/physsci/astronomy/fix/student/chapter9/09f21.html ] is relatively young for a lunar crater, it was formed nearly a billion years ago by a colossal impact [ http://cass.jsc.nasa.gov/expmoon/science/craterstructure.html ]. The center of Copernicus [ http://cass.jsc.nasa.gov/expmoon/Apollo17/ A17_Photography_metric.html#Copernicus ] is about 93 kilometers across. The above picture [ http://cass.jsc.nasa.gov/expmoon/science/craterstructure.html#Copernicus ] was taken in 1972 by the last human mission to the moon: Apollo 17 [ http://antwrp.gsfc.nasa.gov/apod/ap001209.html ]. The prospects for a return have been boosted recently with increased evidence of ice deposits [ http://nssdc.gsfc.nasa.gov/planetary/ice/ice_moon.html ] near the lunar poles [ http://science.nasa.gov/newhome/headlines/ast13oct99_1.htm ]. |
|
Full Moondark
| Title |
Full Moondark |
| Explanation |
The brilliant full Moon [ http://antwrp.gsfc.nasa.gov/apod/ap000113.html ] might not look quite like this to skygazers next Monday, but the image is a mosaic [ http://celestialwonders.com/InvertedFullMoon_12082003.html ] of 18 digital frames recorded when the Moon was only about seven hours past its exact full phase [ http://aa.usno.navy.mil/faq/docs/moon_phases.html ] or time of maximum illumination as viewed [ http://tycho.usno.navy.mil/vphase.html ] from Earth. Here, the pixel values corresponding to light and dark areas have been translated in reverse, or inverted, producing a false-color representation reminiscent of a black and white photographic negative [ http://www.r-cube.co.uk/fox-talbot/index.html ]. Normally bright rays from the large crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ] dominate the southern (bottom) features as easily followed dark lines emanating from the 85 kilometer diameter impact site. Normally dark lunar mare [ http://antwrp.gsfc.nasa.gov/apod/ap001228.html ] appear light and silvery. Traditionally, astronomical images [ http://antwrp.gsfc.nasa.gov/apod/ap960406.html ] recorded on photographic plates [ http://www.astro.virginia.edu/~afs5z/ photography.html ] were directly examined in this negative color scheme, which can help the eye pick out faint details. |
|
Southern Moonscape
| Title |
Southern Moonscape |
| Explanation |
The Moon's [ http://science.nasa.gov/headlines/y2007/ 03aug_dreamyeclipse.htm] south pole is near the top of this sharp telescopic view looking across the southern lunar highlands [ http://www.lunarrepublic.com/atlas/sections/h2.shtml ]. Recorded on August 3rd from Tecumseh [ http://higginsandsons.com/astro/ ], Oklahoma, planet Earth, the foreshortened perspective heightens the impression of a dense field of craters [ http://www.astrosociety.org/education/publications/ tnl/13/13.html ] and makes the craters themselves appear more oval shaped. The prominent crater in the foreground, Moretus, has a diameter of 114 kilometers and lies just west (left) of the Moon's central meridian. For large lunar craters [ http://www.lpi.usra.edu/expmoon/science/ craterstructure.html ], Moretus is young [ http://antwrp.gsfc.nasa.gov/apod/ap010513.html ] and features terraced inner walls and a 2.1 kilometer high, bright central peak, similar in appearance to the more northerly crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap050305.html ]. Just to the right of Moretus is the 95 kilometer diameter crater Curtius. Curtius has older, rounded walls marked by smaller, more recent impact craters. |
|
Dark Lunar Eclipse
| Title |
Dark Lunar Eclipse |
| Explanation |
The Moon passed close to the center of Earth's shadow on August 28th [ http://sunearth.gsfc.nasa.gov/eclipse/LEmono/ TLE2007Aug28/TLE2007Aug28.html ]. Seen best by skywatchers [ http://spaceweather.com/eclipses/ gallery_28aug07.htm ] in western North America, and the Pacific region, the resulting total lunar eclipse was a dark one, lasting about 90 minutes. In this telescopic image taken near mid totality from Yass, NSW Australia [ http://maps.google.com/maps?q=Yass,+NSW,+Australia&ie=UTF8 &ll=-34.777716,148.930664&spn=19.697345,20.522461&t=k&z=5&om=1 ], the 85 kilometer wide ray crater Tycho lies near the top right of the shadowed lunar surface. Of course, even during [ http://science.nasa.gov/headlines/y2007/ 27aug_explodingeclipse.htm ] a total lunar eclipse,the Moon is not completely dark. Instead the Moon remains visible during totality, reflecting reddened light filtering into the Earth's shadow. The light comes from all the sunsets and sunrises [ http://antwrp.gsfc.nasa.gov/apod/ap000115.html ], as seen from the lunar perspective [ http://science.nasa.gov/headlines/y2003/ 04nov_lunareclipse2105.htm ], around the edges of a silhouetted Earth [ http://antwrp.gsfc.nasa.gov/apod/ap070302.html ]. |
|
Eclipsed Moon in Infrared
| Title |
Eclipsed Moon in Infrared |
| Explanation |
The total lunar eclipse of September 1996 [ http://sunearth.gsfc.nasa.gov/eclipse/ LEplot/LEplot1951/LE1996Sep27T.gif ] disappointed many observers in North America who were cursed with cloudy skies. However, the Midcourse Space Experiment [ http://www.ipac.caltech.edu/ipac/msx/msx.html ] (MSX) satellite had a spectacular view from Earth orbit [ http://antwrp.gsfc.nasa.gov/apod/ap001129.html ] and SPIRIT III [ http://www.sdl.usu.edu/programs/spirit3/index ], an onboard infrared telescope, was used to repeatedly image the moon during the eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap010104.html ]. Above is one of the images taken during the 70 minute totality, the Moon completely immersed in the Earth's shadow [ http://antwrp.gsfc.nasa.gov/apod/ap000726.html ]. Infrared light has wavelengths [ http://imagers.gsfc.nasa.gov/ems/waves3.html ] longer than visible light - human's can not see it but feel it as heat. The bright spots correspond to the warm areas on the lunar surface, dark areas are cooler. The brightest spot below and left of center is the crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ], the dark region at the upper right is the Mare Crisium [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/ lunar/mare/mlm.html ]. The series of SPIRIT III images allow the determination of cooling rates for geologically different areas, exploring the physical properties of the Moon's surface [ http://lunar.arc.nasa.gov/ ]. |
|
Aristarchus Plateau
| Title |
Aristarchus Plateau |
| Explanation |
Anchored in the vast lava flows of the Moon's Oceanus Procellarum [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/ lunar/mare/mlm.html ] lies the Aristarchus Plateau [ http://photojournal.jpl.nasa.gov/catalog/PIA00090 ]. The bright impact crater [ http://www.lpi.usra.edu/expmoon/science/ craterstructure.html ] at the corner of the plateau is Aristarchus, a young crater [ http://en.wikipedia.org/wiki/Aristarchus_(crater) ] 42 kilometers wide and 3 kilometers deep. Only slightly smaller, lava flooded Herodotus crater is above and to the left. A valley or rille feature likely carved by rapidly flowing lava or a collapsed lava tunnel, Vallis Schroteri [ http://www.shallowsky.com/moon/rukl18.html ] begins just to the right of Herodotus and winds across the plateau for about 160 kilometers, eventually turning toward the top of the picture. Aristarchus Plateau itself is like a rectangular island about 200 kilometers across, raised up to 2 kilometers or so above the smooth surface of the lunar Ocean of Storms [ http://antwrp.gsfc.nasa.gov/apod/ap020713.html ]. Recorded from a backyard [ http://www.avertedimagination.com/img_pages/ aristarchus_100407.html ] observatory in Buffalo, New York, the contrast of light-colored ejecta around Aristarchus [ http://svs.gsfc.nasa.gov/vis/a000000/a003200/a003275/ ] with surrounding dark, smooth, lava flooded surfaces suggests more familiar snowy scenes [ http://antwrp.gsfc.nasa.gov/apod/ap070203.html ] of planet Earth [ http://antwrp.gsfc.nasa.gov/apod/ap070408.html ]. |
|
Ganymede: Torn Comet - Crate
…
| Title |
Ganymede: Torn Comet - Crater Chain |
| Explanation |
This striking line of 13 closely spaced craters [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA01610 ] on Jupiter's moon Ganymede [ http://cass.jsc.nasa.gov/pub/research/outerp/gany.html ] was photographed by the Galileo spacecraft in 1997. The picture covers an area about 120 miles wide and the chain of craters cuts across a sharp boundary between dark and light terrain. What caused this crater chain? Remarkably, the exploration of the Solar System [ http://sse.jpl.nasa.gov/index.html ], has shown that crater chains [ http://antwrp.gsfc.nasa.gov/apod/ap950715.html ] like this one are not unique [ http://neo.jpl.nasa.gov/images/moon.html ], though they were [ http://stardust.jpl.nasa.gov/news/news12.html ] considered mysterious until a dramatic object lesson was offered by comet Shoemaker-Levy 9. In 1994 many denizens of planet Earth [ http://antwrp.gsfc.nasa.gov/apod/ap971026.html ] watched as huge pieces of this torn comet [ http://antwrp.gsfc.nasa.gov/apod/ap990814.html ] slammed into Jupiter itself in a spectacular series of sequential impacts [ http://antwrp.gsfc.nasa.gov/apod/ap980804.html ]. It is very likely that similar torn comets from the early history of the Solar System are responsible for this and other crater chains [ http://astrosun.tn.cornell.edu/staff/bottke/crater_chain/ chain.html ]. |
|
Mercury's Horizon from MESSE
…
| Title |
Mercury's Horizon from MESSENGER |
| Explanation |
What would it look like to fly past Mercury? Just such an adventure was experienced last week by the MESSENGER spacecraft during its first flyby [ http://messenger.jhuapl.edu/the_mission/mercury_rendezvous.html ] of the strange moon [ http://antwrp.gsfc.nasa.gov/apod/ap030312.html ]-like world nearest the Sun. Pictured above [ http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=1&gallery_id=2&image_id=122 ] is the limb of Mercury [ http://en.wikipedia.org/wiki/Mercury_%28planet%29 ] seen by MESSENGER [ http://en.wikipedia.org/wiki/MESSENGER ] upon approach, from about 1 1/2 Earth [ http://antwrp.gsfc.nasa.gov/apod/ap070514.html ] diameters away. Visible on the hot and barren planet are many craters [ http://liftoff.msfc.nasa.gov/academy/space/solarsystem/meteors/Craters.html ], many appeared to be more shallow than similarly sized craters on the Moon. The comparatively high gravity [ http://www.exploratorium.edu/ronh/weight/ ] of Mercury helps flatten [ http://www.planetary.org/blog/article/00001301/ ] tall structures like high crater walls. MESSENGER [ http://messenger.jhuapl.edu/why_mercury/index.html ] was able to take over 1,000 images of Mercury which will be beamed back to Earth for planetary geologists [ http://en.wikipedia.org/wiki/Planetary_geology ] to study. The robotic MESSENGER spacecraft is scheduled [ http://www.nasa.gov/mission_pages/messenger/timeline/index.html ] to fly past Mercury twice more before firing its thrusters to enter orbit in 2011. |
|
Asteroid 2007 TU24 Passes th
…
| Title |
Asteroid 2007 TU24 Passes the Earth |
| Explanation |
Asteroid 2007 TU24 passed by the Earth yesterday, posing no danger. The space rock, estimated [ http://www.nasa.gov/topics/solarsystem/features/asteroid-20080125.html ] to be about 250 meters across, coasted by just outside the orbit of Earth's Moon. The passing was not very unusual [ http://antwrp.gsfc.nasa.gov/apod/ap050417.html ] -- small rocks strike Earth daily, and in 2003 a rock the size of a bus passed inside the orbit of the Moon, being detected only after passing [ http://antwrp.gsfc.nasa.gov/apod/ap031015.html ]. TU24 was notable partly because it was so large. Were TU24 [ http://en.wikipedia.org/wiki/TU24 ] to have struck land, it might have caused a magnitude [ http://www.geo.mtu.edu/UPSeis/magnitude.html ] seven earthquake [ http://www.youtube.com/watch?v=19fMs633Td4 ] and left a city-sized crater [ http://antwrp.gsfc.nasa.gov/apod/ap990711.html ]. A perhaps larger danger would have occurred were TU24 [ http://www.planetary.org/blog/article/00001309/ ] to have struck the ocean and raised a large tsunami [ http://en.wikipedia.org/wiki/Tsunami ]. This radar image [ http://www.jpl.nasa.gov/news/news.cfm?release=2008-014 ] was taken two days ago. The Arecibo Radio Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap981129.html ] in Puerto Rico [ http://en.wikipedia.org/wiki/Puerto_Rico ] broadcast radar that was reflected by the asteroid and then recorded by the Byrd Radio Telescope [ http://www.gb.nrao.edu/gbt/ ] in Green Bank [ http://www.nrao.edu/administration/personnel_office/greenbank.shtml ], West Virginia [ http://en.wikipedia.org/wiki/West_Virginia ]. The resulting image [ http://www.jpl.nasa.gov/news/news.cfm?release=2008-014 ] shows TU24 to have an oblong and irregular shape. TU24 [ http://www.nasa.gov/topics/solarsystem/features/asteroid-20080128-clips.html ] was discovered only three months ago, indicating that other potentially hazardous asteroids [ http://neo.jpl.nasa.gov/ca/ ] might lurk in our Solar System [ http://space.jpl.nasa.gov/ ] currently undetected. Objects like TU24 [ http://www.space.com/scienceastronomy/080128-asteroid-radar.html ] are hard to detect because they are so faint and move [ http://antwrp.gsfc.nasa.gov/apod/ap060328.html ] so fast. Humanity's ability to scan the sky to detect, catalog, and analyze such objects has increased notably [ http://www.lpl.arizona.edu/css/ ] in recent years. |
|
Lunar Farside from Apollo 13
| Title |
Lunar Farside from Apollo 13 |
| Explanation |
In April of 1970, after an explosion damaged their spacecraft, the Apollo 13 [ http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo13info.html ] astronauts were forced to abandon their plans to make the third manned lunar landing. Still, while coasting around the moon in their desperate attempt to return to earth they were able to photograph the moon's far side. The large, dark, smooth looking feature on the left in this picture is known as the "Mare Moscoviense". It was created by a lava flow filling in a large impact crater on the lunar surface. As suggested by the name, the Mare Moscoviense was first photographed by an early Soviet lunar probe. For more information about the picture see the NASA photo caption. [ http://139.169.29.11/images/pao/AS13/10075506.htm ] |
|
The Colorful Moon
| Title |
The Colorful Moon |
| Explanation |
Do you recognize the Earth's Moon [ http://www.seds.org/nineplanets/nineplanets/ luna.html ] when you see it? The crazy, patchwork appearance of the false-color image [ http://photojournal-b.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA00132 ] makes this almost full view of the Moon's [ http://www.xs4all.nl/~carlkop/golf.html ] familiar near side [ http://antwrp.gsfc.nasa.gov/apod/ap981008.html ] look very strange. The Sea of Tranquillity (Mare Tranquillitatis [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/lunar/ mare/mlm.html ]) is the bright blue area at right, the Ocean of Storms (Oceanus Procellarum) is the extensive blue and orange area on the left, and white lines radiate from the crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ] at bottom center. Recorded in 1992 by the Galileo spacecraft enroute to Jupiter, the picture is a mosaic of 15 images taken through three color filters. The image data were combined in an exaggerated color scheme to emphasize composition differences [ http://antwrp.gsfc.nasa.gov/apod/ap960601.html ] - blue hues reveal titanium rich areas while orange and purple colors show regions relatively poor in titanium and iron. Multicolor images exploring the Moon's [ http://www.lpi.usra.edu/publications/slidesets/ clem2nd.html ] global surface composition were made in 1994 by the Clementine spacecraft. |
|
Apollo 14 Deploys ALSEP
| Title |
Apollo 14 Deploys ALSEP |
| Explanation |
After the lunar module [ http://antwrp.gsfc.nasa.gov/apod/ap951209.html ] of Apollo 14 [ http://bang.lanl.gov/solarsys/apo14.htm ] set down on the Moon [ http://antwrp.gsfc.nasa.gov/apod/ap951128.html ], Astronauts Alan Shepard and Edgar Mitchell deployed the Apollo Lunar Surface Experiments Package (ALSEP) and collected samples of lunar material. The ALSEP scientific experiments included a seismometer [ http://gldfs.cr.usgs.gov/ ] sensitive to slight lunar surface movements, and charged particle detectors which measured the solar wind [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#sol_wind ]. The seismometer successfully measured surface tremors interpreted as moonquakes [ http://antwrp.gsfc.nasa.gov/apod/ap950904.html ] and meteoroids [ http://ccf.arc.nasa.gov/sst/ ] striking the Moon [ http://antwrp.gsfc.nasa.gov/apod/ap950903.html ], while the solar wind [ http://www.sel.bldrdoc.gov/effects.html ] experiment was sensitive enough to detect the element argon [ http://www.cchem.berkeley.edu/Table/Ar.html ]. These and other ALSEP experiments helped classify the internal structure and magnetic field of Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap950629.html ]. Shepard and Mitchell also made a geology traverse to the rim of Cone Crater, carrying their tools and sample containers in the Modular Equipment Transporter (MET). In this picture Alan Shepard assembles a core tube which he will then hammer into the surface. |
|
Apollo 15: Driving on the Mo
…
| Title |
Apollo 15: Driving on the Moon |
| Explanation |
Apollo 15 [ http://ees5-www.lanl.gov/APOLLO/a15.summary.html ] astronaut James Irwin [ http://ees5-www.lanl.gov/APOLLO/a15.crew.html#irwinbio ] works on the first Lunar Roving Vehicle [ http://www.nasm.edu/APOLLO/AS15/LRV.html ], before he and fellow astronaut David Scott [ http://ees5-www.lanl.gov/APOLLO/a15.crew.html#scottbio ] take it out for a drive. Sloping up behind the lunar module [ http://www.nasm.edu/APOLLO/LMordered.html ]"Falcon" on the left are lunar mountains Hadley Delta [ http://antwrp.gsfc.nasa.gov/apod/ap960222.html ] and Apennine Front, while about 5 kilometers behind Irwin is St. George Crater. The explorations conducted during the Apollo lunar missions discovered much about our Moon [ http://www.nasm.edu/APOLLO/LunarTop10.html ], including that the Moon is made of ancient rock, that the Moon's composition is similar to Earth's, that life is not evident there, that the Moon underwent a great hot melting in its distant past, that the Moon has suffered from numerous impacts as shown by its craters, and that the Moon's surface is covered by a layer of rock fragments and dust. |
|
Aristarchus Plateau
| Title |
Aristarchus Plateau |
| Explanation |
Anchored in the vast lava flows of the Moon's Oceanus Procellarum [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/ lunar/mare/mlm.html ] lies the Aristarchus Plateau [ http://www.lpi.usra.edu/research/clemen/ cmaris.html ]. Recorded from a backyard observatory on planet Earth, this sharp, amazingly colorful view [ http://www.rc-astro.com/solar_system/moon/ aristarchus.html ] nicely captures the geologically diverse area, including [ http://www.space.edu/moon/atlas/Nearside/ AristrPlat.html ] the brownish plateau, Aristarchus and Herodotus craters, and the meandering Vallis Schroteri. The bright impact crater at the corner of the plateau is Aristarchus, a young crater [ http://www.nrl.navy.mil/clementine/clem_collect/ arist.html ] 42 kilometers wide and 3 kilometers deep, surrounded by a radial system of light-colored rays [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ]. Only slightly smaller, lava flooded Herodotus crater is above and to the left. A valley or rille feature likely carved by rapidly flowing lava or a collapsed lava tunnel, Vallis Schroteri [ http://www.shallowsky.com/moon/rukl18.html ] begins just to the right of Herodotus and winds across the plateau for about 160 kilometers, eventually turning toward the top of the picture and the shadow of the lunar terminator [ http://antwrp.gsfc.nasa.gov/apod/ap010428.html ]. Aristarchus Plateau itself is like a rectangular island about 200 kilometers across, raised up to 2 kilometers or so above the smooth surface of the lunar Ocean of Storms [ http://antwrp.gsfc.nasa.gov/apod/ap020713.html ]. |
|
A Year of Assessing Astronom
…
| Title |
A Year of Assessing Astronomical Hazards |
| Explanation |
Could an asteroid destroy civilization on Earth? Mountain-sized space rocks [ http://antwrp.gsfc.nasa.gov/apod/ap000417.html ] could potentially impact the Earth [ http://impact.arc.nasa.gov/ ] causing global effects, and perhaps even be mistaken for a nuclear blast of terrestrial origin. Such large impacts are rare but have happened before [ http://antwrp.gsfc.nasa.gov/apod/ap990711.html ]. Modern telescopes have therefore begun to scan the skies for signs of approaching celestial hazards [ http://antwrp.gsfc.nasa.gov/apod/ap020623.html ]. Over the past year, projects such as Spacewatch [ http://spacewatch.lpl.arizona.edu/ ] and Spaceguard [ http://spaceguard.ias.rm.cnr.it/SGF/ ] have continually discovered previously unknown asteroids [ http://www.nineplanets.org/asteroids.html ] that indeed pass near the Earth. Such projects are still rather modest, however. In June, 100-meter asteroid 2002 MN [ http://SkyandTelescope.com/news/current/article_641_1.asp ] was discovered only "after" it whizzed by [ http://antwrp.gsfc.nasa.gov/apod/ap020817.html ] the Earth, crossing even within the orbit of the Moon. This year brought much discussion in the astronomical community of expanding technology [ http://www.ifa.hawaii.edu/pan-starrs/neos.html ] to discover most large Near Earth Objects [ http://neo.jpl.nasa.gov/ ] and extend the time between discovery [ http://antwrp.gsfc.nasa.gov/apod/ap021009.html ] and impact for all potential astronomical hazards [ http://www.pbs.org/wgbh/nova/gamma/milkyway.html ]. Pictured above [ http://www.iaaa.org/exhibit/gall1.html#8 ] is an illustration of a busy planetary system [ http://antwrp.gsfc.nasa.gov/apod/ap020724.html ], showing the view of a planet ringed with space debris from a recently formed crater of an orbiting moon. |
|
A Spherule from Outer Space
| Title |
A Spherule from Outer Space |
| Explanation |
When a meteorite [ http://www.nineplanets.org/meteorites.html ] strikes the Moon [ http://antwrp.gsfc.nasa.gov/apod/moon.html ], the energy of the impact melts some of the splattering rock [ http://www.solarviews.com/eng/edu/micromet.htm ], a fraction of which might cool into tiny glass beads [ http://antwrp.gsfc.nasa.gov/apod/ap010523.html ]. Many of these glass beads were present in lunar soil samples [ http://www.hq.nasa.gov/office/pao/History/alsj/tools/Welcome.html ] returned to Earth by the Apollo missions [ http://www.nasm.edu/apollo/ ]. Pictured above [ http://www.lbl.gov/Science-Articles/Archive/lunar-spherule.html ] is one such glass spherule [ http://www.m-w.com/cgi-bin/dictionary?spherule ] that measures only a quarter of a millimeter [ http://lamar.colostate.edu/~hillger/everyday.htm ] across. This spherule is particularly interesting because it has been victim to an even smaller impact. A miniature crater [ http://antwrp.gsfc.nasa.gov/apod/ap990711.html ] is visible on the upper left, surrounded by a fragmented area caused by the shockwaves [ http://antwrp.gsfc.nasa.gov/apod/ap010623.html ] of the small impact. By dating many of these impacts, some astronomers estimate [ http://www.lbl.gov/Science-Articles/Archive/lunar-spherule.html ] that cratering [ http://antwrp.gsfc.nasa.gov/apod/ap010428.html ] on our Moon increased roughly 500 million years ago and continues even today. |
|
A Violet Moon
| Title |
A Violet Moon |
| Explanation |
Checking out the Galileo spacecraft's cameras [ http://newproducts.jpl.nasa.gov/galileo/sepo/sepo.html ] during its December 1992 flyby of Earth's Moon, controllers took this dramatically illuminated picture [ http://www.jpl.nasa.gov/galileo/messenger/oldmess/Moon2.html ] through a violet filter. The view looks down on the Moon's north polar region [ http://antwrp.gsfc.nasa.gov/apod/ap960622.html ] with the Sun shining from the left at a low angle and the direction toward the moon's North pole toward the lower right. Across the image upper left stretches the smooth volcanic plain [ http://antwrp.gsfc.nasa.gov/apod/ap960112.html ] of the Mare Imbrium [ http://volcano.und.nodak.edu/vwdocs/ planet_volcano/lunar/mare/Overview.html ]. Pythagoras crater, 65 miles wide, is near the center of the image -- mostly in shadow, its central peak just catches the sunlight. Yesterday, the Moon made its closest approach to Earth and was full for the second time in July (as reckoned by UT dates) [ http://www.ast.cam.ac.uk/pubinfo/leaflets/time/time.html ]. The closest point in the Moon's orbit is referred to as Lunar Perigee, a mere 221,797 miles at 8 hours UT. The second full moon in a month is known as a "Blue Moon" [ http://antwrp.gsfc.nasa.gov/apod/ap960730.html ]. |
|
Galileo Explores Europa
| Title |
Galileo Explores Europa |
| Explanation |
Details of the crazed cracks [ http://newproducts.jpl.nasa.gov/galileo/ganymede/p47183.html ] criss-crossing Europa's frozen surface [ http://antwrp.gsfc.nasa.gov/apod/ap960813.html ] are apparent in this mosaic of the Galileo spacecraft's latest images [ http://newproducts.jpl.nasa.gov/galileo/index.html ] of Jupiter's ice-covered moon. Curious white stripes, also seen by Voyager [ http://antwrp.gsfc.nasa.gov/apod/ap950905.html ], are clearly visible marking the center of the wide dark fractures. One theory suggests that "dirty geysers" erupting along the cracks deposited darker material followed by a flow of cleaner water ice which produced the stripe. The above image [ ftp://ftp.hq.nasa.gov/pub/pao/pressrel/1996/96-164.txt ] also shows an impact crater about 18.5 miles in diameter surrounded by white ejecta (lower left) and a curving x-pattern at bottom left which suggests fractures between icy plates filled with slush frozen in place. " Is there now or was there ever liquid water [ http://antwrp.gsfc.nasa.gov/apod/ap951118.html ] beneath Europa's surface [ http://antwrp.gsfc.nasa.gov/apod/ap960806.html ]? " These latest results still hold out that possibility -- and so the possibility of life. Europa, along with Mars [ http://antwrp.gsfc.nasa.gov/apod/ap960808.html ] and Saturn's moon Titan [ http://antwrp.gsfc.nasa.gov/apod/ap960716.html ] is considered to be one of the few places in our Solar System, beyond [ http://antwrp.gsfc.nasa.gov/apod/ap960701.html ] Earth, where primitive life forms could have developed. Galileo's close flyby of this tantalizing moon is scheduled for December [ http://newproducts.jpl.nasa.gov/galileo/background.html ] of this year. |
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Lunar Farside from Apollo 11
| Title |
Lunar Farside from Apollo 11 |
| Explanation |
The far side of the Moon [ http://www.nineplanets.org/luna.html ] is rough and filled with craters [ http://antwrp.gsfc.nasa.gov/apod/ap010428.html ]. By comparison, the near side of the Moon [ http://antwrp.gsfc.nasa.gov/apod/moon.html ], the side we always see, is relatively smooth. Since the Moon is rotation locked [ http://antwrp.gsfc.nasa.gov/apod/ap010218.html ] to always point the same side toward Earth, humanity has only glimpsed the lunar farside [ http://antwrp.gsfc.nasa.gov/apod/ap001021.html ] recently -- last century. The light highlands [ http://www.hq.nasa.gov/office/pao/History/SP-4214/ch13-7.html ] of the far side [ http://antwrp.gsfc.nasa.gov/apod/ap981008.html ] are older than the dark Maria [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/lunar/mare/mlm.html ] of the near side. A thinner crust on the near side that allowed for more dark lava flows [ http://cmex-www.arc.nasa.gov/CMEX/data/catalog/RecentVolcanismOnMars/LunarLavaFlow.html ] is thought to be the cause of differences between the two sides. The cause for the crust [ http://www.windows.ucar.edu/tour/link=/earth/moon/lunar_interior_structure.html ] thickness differences is still being researched, however. The large impact basin pictured above [ http://www.hq.nasa.gov/office/pao/History/ap11ann/kippsphotos/apollo.html ] is Crater 308 [ http://csep10.phys.utk.edu/astr161/lect/moon/moon_surface.html ]. It spans about 30 kilometers and was photographed [ http://hyperphysics.phy-astr.gsu.edu/hbase/solar/mooncrater.html ] by crew of Apollo 11 [ http://www.hq.nasa.gov/office/pao/History/ap11ann/introduction.htm ] as they circled the Moon in 1969. |
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The Largest Impact Crater
| Title |
The Largest Impact Crater |
| Explanation |
What is the largest known impact crater [ http://bang.lanl.gov/solarsys/edu/craters.htm ] in the Solar System? Over 1300 miles across, the South Pole [ http://antwrp.gsfc.nasa.gov/apod/ap951128.html ]-Aitken Basin on the farside [ http://antwrp.gsfc.nasa.gov/apod/ap950914.html ] of Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/lib/moon.html ] holds that distinction. Circled above in a false color mosaic of Clementine images [ http://cass.jsc.nasa.gov/pub/expmoon/CLEM/clemtext.html ] it was caused when an asteroid [ http://antwrp.gsfc.nasa.gov/apod/ap960215.html ] or comet sized object [ http://antwrp.gsfc.nasa.gov/apod/ap950821.html ] crashed into the surface, penetrating the lunar mantle. In general, the rocky terrestrial planets and moons are scarred and battered from frequent repeated bombardment by large objects during our Solar System's early years. On Earth, continuous geological activity has hidden much of the damage [ http://antwrp.gsfc.nasa.gov/apod/ap960604.html ], but the surface of the smaller, less active Moon [ http://cass.jsc.nasa.gov/moon.html ] bears testimony to a shared history of fierce and frequent impacts. At the present time in the vicinity of Earth, the bombardment continues [ http://omzg.comcen-1.nsk.su/tunguska/TUNGUSKA.html ] - fortunately at a greatly reduced rate [ http://ccf.arc.nasa.gov/sst/main.html ]. |
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The Earth and Moon from Mars
| Title |
The Earth and Moon from Mars |
| Explanation |
What does Earth [ http://antwrp.gsfc.nasa.gov/apod/ap010204.html ] look like from Mars [ http://www.nineplanets.org/mars.html ]? The first image [ http://photojournal.jpl.nasa.gov/catalog/PIA04531 ] of Earth from the red planet was captured earlier this month by the camera onboard the Mars Global Surveyor spacecraft [ http://antwrp.gsfc.nasa.gov/apod/ap030526.html http://mars.jpl.nasa.gov/mgs/overvu/overview.html ] currently orbiting Mars. Features visible on Earth include the Pacific Ocean [ http://www.cia.gov/cia/publications/factbook/geos/zn.html ], clouds [ http://seaborg.nmu.edu/Clouds/types.html ], much of South America [ http://www.infoplease.com/atlas/southamerica.html ], and part of North America [ http://www.infoplease.com/atlas/northamerica.html ]. Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap020316.html ] is visible on the upper right, with the crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ] brightening the lower part. Previously, Earth has been imaged from the Moon [ http://antwrp.gsfc.nasa.gov/apod/ap000701.html ] and spacecraft [ http://antwrp.gsfc.nasa.gov/apod/ap011015.html ] across [ http://antwrp.gsfc.nasa.gov/apod/ap020127.html ] the [ http://antwrp.gsfc.nasa.gov/apod/ap000325.html ] Solar [ http://antwrp.gsfc.nasa.gov/apod/ap980904.html ] System [ http://setiathome.ssl.berkeley.edu/pale_blue_dot.html ]. |
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Sunset Moonlight
| Title |
Sunset Moonlight |
| Explanation |
November's lunar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap031107.html ] was one of the shortest in recent years and also one of the brightest -- demonstrating that the Earth's shadow is not completely dark. The eclipsed Moon remained easily visible during totality, reflecting reddened light filtering on to its surface from all the sunsets [ http://antwrp.gsfc.nasa.gov/apod/ap030412.html ] and sunrises [ http://antwrp.gsfc.nasa.gov/apod/ap020227.html ], as seen from the lunar perspective [ http://science.nasa.gov/headlines/y2003/ 04nov_lunareclipse2105.htm ], around the edges of a silhouetted Earth. Hoping to view the celestial shadow play [ http://www.xs4all.nl/~carlkop/maansverd/ leclips2.html ] from the Earth's night side near Cologne, Germany, about 400,000 kilometers [ http://www.seds.org/nineplanets/nineplanets/luna.html ] from the lunar surface, amateur astronomer [ http://www.goldtech.de ] Markus Strassfeld packed a digital camera and telescope and drove about 10 kilometers outside the city to escape the bright city lights [ http://antwrp.gsfc.nasa.gov/apod/ap020810.html ]. Fortunately, the sky cleared about an hour before the eclipse began and he was able to record this sharp image of sunsets illuminating the totally eclipsed Moon. Young ray crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ], about 85 kilometers across, stands out near the Moon's brighter southern edge. |
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Eclipsed Moon in Infrared
| Title |
Eclipsed Moon in Infrared |
| Explanation |
The total lunar eclipse of September 1996 [ http://sunearth.gsfc.nasa.gov/eclipse/ LEplot/LEplot1951/LE1996Sep27T.gif ] disappointed many observers in North America who were cursed with cloudy skies. However, the Midcourse Space Experiment [ http://www.ipac.caltech.edu/ipac/msx/msx.html ] (MSX) satellite had a spectacular view from Earth orbit [ http://antwrp.gsfc.nasa.gov/apod/ap001129.html ] and SPIRIT III [ http://www.sdl.usu.edu/programs/spirit3/index ], an on board infrared telescope, was used to repeatedly image the moon during the eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap010104.html ]. Above is one of the images taken during the 70 minute totality, the Moon completely immersed in the Earth's shadow [ http://antwrp.gsfc.nasa.gov/apod/ap000726.html ]. Infrared light has wavelengths [ http://imagers.gsfc.nasa.gov/ems/waves3.html ] longer than visible light - humans can not see it but feel it as heat. The bright spots correspond to the warm areas on the lunar surface, dark areas are cooler. The brightest spot below and left of center is the crater Tycho [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ], the dark region at the upper right is the Mare Crisium [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/ lunar/mare/mlm.html ]. The series of SPIRIT III images allow the determination of cooling rates for geologically different areas, exploring the physical properties of the Moon's surface [ http://lunar.arc.nasa.gov/ ]. |
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