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Images of Jet Propulsion Laboratory (JPL) and Goddard Space Flight Center (GSFC) from 1999
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The Trifid Nebula: Stellar S
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The Trifid Nebula: Stellar Sibling Rivalry |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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The Secret Lives of Galaxies Unveiled in Deep Survey |
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Mount St. Helens Flyover
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Mount St. Helens Flyover |
| Description |
This Advanced Spaceborne Thermal Emission and Reflection Radiometer [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://asterweb.jpl.nasa.gov/ ] (ASTER) image of Mt. St. Helens volcano in Washington State was acquired on August 8, 2000 and covers an area of 37 by 51 km. Mount Saint Helens, a volcano in the Cascade Range of southwestern Washington that had been dormant since 1857, began to show signs of renewed activity in early 1980. On 18 May 1980, it erupted with such violence that the top of the mountain was blown off, spewing a cloud of ash and gases that rose to an altitude of 19 kilometers. The blast killed about 60 people and destroyed all life in an area of some 180 square kilometers (some 70 square miles), while a much larger area was covered with ash and debris. It continues to spit forth ash and steam intermittently. As a result of the eruption, the mountain's elevation decreased from 2,950 meters to 2,549 meters. The simulated fly-over was produced by draping ASTER visible and near infrared image data over a digital topography model, created from ASTER?s 3-D stereo bands. The color was computer enhanced to create a ?natural? color image, where the vegetation appears green. The topography has been exaggerated 2 times to enhance the appearance of the relief. Landsat7 aquired an image of Mt. St. Helens [ http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=3321 ] on August 22, 1999. Image and animation courtesy NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. |
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New Measurements of Arctic O
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New Measurements of Arctic Ozone |
| Description |
The winter of 2004-2005 saw the second highest chemical ozone destruction ever observed over the Arctic. Polar ozone is destoyed when chlorine, cold temperatures, and sunlight mix in the atmosphere 8-50 kilometers above the Earth's surface. Since ozone shields the Earth from ultraviolet light, the high-energy light that causes sunburns and is associated with skin cancers, low ozone levels could threaten human health. Ultraviolet levels remained near normal through the winter, however, because unusual weather conditions brought ozone from the Earth's ozone-rich mid-latitudes to the pole to fill in the gaps left by the extreme ozone depletion. These images show the fluctuations in ozone during the Arctic winter of 2005. The top two images show the average total column ozone over the Arctic during the months of January and March, 2005, and the lower image shows total column ozone on a single day, March 11, 2005. The images are based on data collected by the Ozone Monitoring Instrument [ http://www.knmi.nl/omi/publ-en/news/index.html ] (OMI) aboard NASA's Aura [ http://aura.gsfc.nasa.gov/ ] satellite. During this time period, the Microwave Limb Sounder, another instrument on the Aura satellite, measured 50 percent ozone loss, the second-highest level ever observed behind the 60 percent loss measured in 1999-2000. Despite this, the lowest total column ozone values in polar regions are slightly higher in March than in January, on average, as evidenced by the broad splashes of red that represent high ozone levels. Stratospheric winds carried the ozone north into the Arctic, compensating for the significant chemical loss, so that no blue or purple holes representing low ozone levels appear in the March image. Black circles over the North pole show where OMI did not collect data. On a single day, March 11, 2005, ozone was distributed far more unevenly, with dark red, almost black areas of high ozone over the Aleutian Islands, Asia, and Europe, and a pale blue thin spot over Iceland and Greenland. This reveals that even though ozone values appeared to be near normal on average throughout March, some regions experienced much lower ozone levels—and therefore, a greater exposure to UV light—on an individual day. For more information and images, see "NASA Spacecraft Measures Unusual 2005 Arctic Ozone Conditions" [ http://www.nasa.gov/vision/earth/lookingatearth/aura-060205.html ] on the NASA portal. Image courtesy NASA/JPL/Agency for Aerospace Programs (Netherlands)/Finnish Meteorological Institute |
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Sharm El Sheik, Egypt
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Sharm El Sheik, Egypt |
| Description |
The Red Sea golf resort in Sharm El Sheik, Egypt, where President Clinton met with Israeli Prime Minister Ehud Barak and Palestinian Authority President Yasser Arafat, stands out against the desert landscape in this image acquired on August 25, 2000. This image of the southern tip of the Sinai Peninsula shows an area about 30 by 30 kilometers (19 by 19 miles) in the visible and near infrared wavelength region. Vegetation appears in red. The blue areas in the water at the top and bottom of the image are coral reefs. The airport is visible just to the north of the golf resort. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high- resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface. The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats, monitoring potentially active volcanoes, identifying crop stress, determining cloud morphology and physical properties, wetlands Evaluation, thermal pollution monitoring, coral reef degradation, surface temperature mapping of soils and geology, and measuring surface heat balance. Image courtesy NASA GSFC, MITI, ERSDAC, JAROS, and U.S./Japan ASTER Science Team |
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Shrimp Farming in Ecuador
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Shrimp Farming in Ecuador |
| Description |
Like fields of blue, rectangular shrimp farms line the coast of Ecuador south of the city of Guayaquil in these images. Worldwide, wetlands and coastal mangrove forests have been converted to shrimp ponds in order to farm these crustaceans for food and sale. In Ecuador, the industry started in the late 1960s and rapidly grew. By 1999, 175,255 hectares of land had been converted to shrimp farms. That year, Ecuador was the fourth largest shrimp producer in the world, and the largest in the Western Hemisphere, according to the United Nations Food and Agriculture Organization. In Ecuador, as elsewhere, shrimp farms are typically built along the shore where salt water is easily accessible. Though Ecuador's mangrove forests declined as shrimp farming and other coastal development occurred, salt flats or salt marshes on slightly higher ground have also been converted, as illustrated in these images. The lower image was taken by the Landsat satellite on April 29, 1991. Shrimp farms cover much of the land shown in the image, but a broad swath of tan-gray salt flat still lines the inlet. By March 6, 2006, when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER [ http://asterweb.jpl.nasa.gov/ ]) satellite took the top image, the salt flat had almost entirely been converted to shrimp farms. A small canal connects the network of shrimp tanks to the inlet, providing a fresh source of water. The large images provide a broader perspective on the extent of the development. In the 1991 Landsat image, 143 square kilometers of land had been converted to shrimp ponds. In the 2006 ASTER image, shrimp farms cover 243 square kilometers. Roughly 83 percent of the region's wetlands and salt flats were eliminated by shrimp farms. NASA images created by Jesse Allen, Earth Observatory. ASTER data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. [ http://asterweb.jpl.nasa.gov/ ] Landsat data obtained from the University of Maryland's Global Land Cover Facility. [ http://www.landcover.org/ ] |
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Shrimp Farming in Ecuador
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Shrimp Farming in Ecuador |
| Description |
Like fields of blue, rectangular shrimp farms line the coast of Ecuador south of the city of Guayaquil in these images. Worldwide, wetlands and coastal mangrove forests have been converted to shrimp ponds in order to farm these crustaceans for food and sale. In Ecuador, the industry started in the late 1960s and rapidly grew. By 1999, 175,255 hectares of land had been converted to shrimp farms. That year, Ecuador was the fourth largest shrimp producer in the world, and the largest in the Western Hemisphere, according to the United Nations Food and Agriculture Organization. In Ecuador, as elsewhere, shrimp farms are typically built along the shore where salt water is easily accessible. Though Ecuador's mangrove forests declined as shrimp farming and other coastal development occurred, salt flats or salt marshes on slightly higher ground have also been converted, as illustrated in these images. The lower image was taken by the Landsat satellite on April 29, 1991. Shrimp farms cover much of the land shown in the image, but a broad swath of tan-gray salt flat still lines the inlet. By March 6, 2006, when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER [ http://asterweb.jpl.nasa.gov/ ]) satellite took the top image, the salt flat had almost entirely been converted to shrimp farms. A small canal connects the network of shrimp tanks to the inlet, providing a fresh source of water. The large images provide a broader perspective on the extent of the development. In the 1991 Landsat image, 143 square kilometers of land had been converted to shrimp ponds. In the 2006 ASTER image, shrimp farms cover 243 square kilometers. Roughly 83 percent of the region's wetlands and salt flats were eliminated by shrimp farms. NASA images created by Jesse Allen, Earth Observatory. ASTER data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. [ http://asterweb.jpl.nasa.gov/ ] Landsat data obtained from the University of Maryland's Global Land Cover Facility. [ http://www.landcover.org/ ] |
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Aeolian Mars
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Aeolian Mars |
| Explanation |
Mars' [ http://mars.ivv.nasa.gov/resources/mars_data-information/ mars_earth_comp_NSSDC_and.html ]atmosphere is relatively thin, still when martian winds [ http://antwrp.gsfc.nasa.gov/apod/ap990520.html ] blow they weather [ http://learn.jpl.nasa.gov/projectspacef/weather.html ] and shape its surface [ http://www.msss.com/mars_images/moc/1_31_00_dunes/index.html ]. Like familiar aeolian [ http://darkwing.uoregon.edu/~millerm/DVdune1.html ] features on Earth [ http://ruidoso.net/chamber/outdoors/whitesan.html ], this field of dunes within Mars' Rabe crater exhibits graceful undulating ridges [ http://photo.net/photo/pcd0738/great-sand-dune-ridge-7.tcl ] which can shift as windblown material is deposited on the dunes' windward face and falls away down the steeper leeward slopes. Indicated by the arrow, the dark trails are signs that the martian [ http://amor.rz.hu-berlin.de/~h0444ihv/private/marslit/marsbib.html ] sand has avalanched down the steep slopes in the recent past. Rippling patterns of smaller dunes are also visible in this sharp high-resolution view [ http://www.msss.com/mars_images/moc/1_31_00_dunes/ rabe_dunes/index.html ] along with criss-crossing dark trails which may be evidence of local dust-devil [ http://www.msss.com/mars_images/moc/8_10_99_releases/ moc2_171/index.html ] windstorms. The image is about 3 kilometers across and was recorded in March of 1999 by the orbiting Mars [ http://www.msss.com/mars_images/moc/1_2000_jan1movie/index.html ] Global Surveyor spacecraft. |
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A Continuous Eruption on Jup
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A Continuous Eruption on Jupiter's Moon Io |
| Explanation |
A volcano on Jupiter's moon Io [ http://www.seds.org/nineplanets/nineplanets/io.html ] has been photographed recently during an ongoing eruption. Hot glowing lava is visible on the left on this representative-color image [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02550 ]. A glowing landscape of plateaus and valleys covered in sulfur [ http://pearl1.lanl.gov/periodic/elements/16.html ] and silicate rock [ http://windows.ivv.nasa.gov/cgi-bin/tour_def/glossary/silicate_rock.html ] surrounds the active volcano [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/Io/Overview.html ]. Many features including several of the dark spots [ http://antwrp.gsfc.nasa.gov/apod/ap971110.html ] have evolved between February 2000, when the robot spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/spacecraft.html ] currently orbiting Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] took this picture, and November 1999. Io [ http://cass.jsc.nasa.gov/pub/research/outerp/io.html ] is slightly larger than Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ] and is the closest large moon to Jupiter [ http://galileo.jpl.nasa.gov/jupiter/jupiter.html ]. The above image [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02550 ] shows a region about 250 kilometers across. How the internal structure of Io [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1990Icar...85..309R ] creates these active volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap961027.html ] remains under investigation. |
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Full Throttle For Deep Space
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Full Throttle For Deep Space 1 |
| Explanation |
At full throttle the Deep Space 1 [ http://nmp.jpl.nasa.gov/ds1/index.html ] spacecraft's innovative ion drive [ http://antwrp.gsfc.nasa.gov/apod/ap981026.html ] produces about 1/50th of a pound of thrust ... a force so great that it would just about [ http://www.howstuffworks.com/question329.htm ] hold up a piece of paper on planet Earth! Still, powered by solar arrays ion propulsion systems [ http://nmp.jpl.nasa.gov/ds1/tech/sep.html ] can run continuously. For long duration space missions they ultimately win out [ http://www.jpl.nasa.gov/releases/99/discoverawards.html ] over the powerful but brief blasts of less efficient chemical rockets [ http://antwrp.gsfc.nasa.gov/apod/ap990717.html ]. Deep Space 1 is seen here [ http://www2.jpl.nasa.gov/files/images/captions/98pc1191.txt ] suspended in an assembly room, a folded solar array [ http://nmp.jpl.nasa.gov/ds1/tech/scarlet.html ] resting above the circular ion propulsion module. Already a successful technology [ http://nmp.jpl.nasa.gov/ds1/tech/index.html ] demonstrator with experimental autonomous software [ http://rax.arc.nasa.gov/ ], the spacecraft flew by asteroid 9969 Braille [ http://antwrp.gsfc.nasa.gov/apod/ap990805.html ] in July of 1999 but later that year, in November, the robot probe was nearly lost [ http://www.jpl.nasa.gov/status/ds1/ds120000121.html ] due to the failure of its wide-field star tracker camera. Now, the adventures of Deep Space 1 can continue. Engineers were able to reprogram the navigation system to utilize another on-board camera and on 28 June 2000 the ion drive was throttled up. Once again steering [ http://nmp.jpl.nasa.gov/ds1/mrlog.html ] by the stars, Deep Space 1 is presently bound [ http://science.nasa.gov/headlines/y2000/ast11jul_1.htm ] for a September 2001 rendezvous with periodic Comet Borrelly [ http://comets.amsmeteors.org/comets/pcomets/019p.html ]. |
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Light Deposits Indicate Wate
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Light Deposits Indicate Water Flowing on Mars |
| Explanation |
What's creating light-toned deposits on Mars? Quite possibly -- water! Images of the same parts of mid-latitude Mars [ http://antwrp.gsfc.nasa.gov/apod/ap010628.html ] taken over the years but released [ http://www.msss.com/mars_images/moc/2006/12/06/gullies/sirenum_crater/index.html ] only last week have shown unexpected new light-toned deposits where there were none before. One clear case is shown above [ http://photojournal.jpl.nasa.gov/catalog/PIA09028 ], where the same crater on Mars is shown as photographed in 1999 August and again in 2005 September. The unusual deposit is visible only on the more recent photograph. Apparent tributaries near the bottom bolster the leading hypothesis [ http://planetary.org/blog/article/00000789/ ] that water gushed out of the crater wall, flowed down the crater, and soon evaporated into the thin Martian atmosphere [ http://www.daviddarling.info/encyclopedia/M/Marsatmos.html ]. Although frozen water-ice [ http://antwrp.gsfc.nasa.gov/apod/ap050720.html ] has been known near the Martian poles [ http://antwrp.gsfc.nasa.gov/apod/ap981216.html ] for years, free flowing surface water like this was not expected to be seen in the mid-latitudes of Mars [ http://en.wikipedia.org/wiki/Mars ]. If confirmed, such water springs might make more of Mars hospitable to life [ http://mars.jpl.nasa.gov/science/life/ ] and human visitation [ http://www.nasa.gov/mission_pages/exploration/main/index.html ] than previously believed. |
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Sail On, Stardust
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Sail On, Stardust |
| Explanation |
Spacecraft on long interplanetary voyages [ http://www-spof.gsfc.nasa.gov/stargaze/Sintro.htm ] often use the planets themselves as gravitational "sling shots" to boost them along their way. Launched [ http://stardust.jpl.nasa.gov/news/ commemorative.html ] in February of 1999 on a historic voyage to a comet, the Stardust spacecraft [ http://stardust.jpl.nasa.gov/news/ega/ ] is no different. On 15 January 2001 Stardust made its closest approach to planet Earth [ http://stardust.jpl.nasa.gov/news/status/010115.html ] since launch, coming within about 6,000 kilometers of the surface. It used this gravity assist maneuver [ http://www.jpl.nasa.gov/basics/bsf4-1.htm#gravity ] to increase its speed and alter its trajectory toward an encounter with comet Wild 2 [ http://www.ssep.org/stardust/wild-2.html ], which it should reach in 2004. Shortly before its time of closest approach, astronomer Gordon Garradd recorded this exposure [ http://www.ozemail.com.au/~loomberah/stardust.htm ] of Stardust sailing through the skies above Loomberah, Australia. Nearby and moving fast [ http://stardust.jpl.nasa.gov/news/ega/images.html ], the spacecraft appears as a streak against a background of faint stars in the constellation Cetus [ http://www.astronomical.org/constellations/cet.html ]. Stardust cruised within just 98,000 kilometers of the Moon [ http://stardust.jpl.nasa.gov/news/ega/lunar.html ] about 15 hours later. After collecting [ http://stardust.jpl.nasa.gov/tech/ aerogel.html ] dust from the tail of comet Wild 2, Stardust's voyage [ http://stardust.jpl.nasa.gov/mission/details.html ] will continue -- as it returns the samples to Earth in 2006. |
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Swiss Cheese-Like Landscape
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Swiss Cheese-Like Landscape on Mars |
| Explanation |
Why do parts of the south pole of Mars look like swiss [ http://www.nytimes.com/learning/students/scienceqa/archive/001130.html ] cheese [ http://www.ilovecheese.com/about/abhist.html ]? This little-understood landscape [ http://www.spacescience.com/headlines/y2000/ast09mar_1.htm ] features flat-topped mesas [ http://www.ut.blm.gov/monument/Visitor_Information/pictures/no_mans_mesa.html ] nearly 4 meters high and circular indentations over 100 meters across. Since this swiss-cheese topography is unique to the polar cap [ http://antwrp.gsfc.nasa.gov/apod/ap981216.html ] covering southern Mars [ http://antwrp.gsfc.nasa.gov/apod/ap980210.html ], exogeologists speculate [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000DPS....32.5906B ] that mesa composition might be high in frozen carbon dioxide [ http://www.rockitscience.com/dryice.html ] (dry ice [ http://www.howstuffworks.com/question264.htm ]). Additionally, dry ice [ http://www.west.net/~science/co2.htm ] might have had a role in this strange landscape [ http://www.jpl.nasa.gov/releases/2000/mgscheese.html ]'s creation. In the above picture [ http://www.msss.com/mars_images/moc/nature_polar/np_2c/index.html ], the Martian surface is illuminated by sunlight from the upper right. The above picture [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02367 ] was taken in August 1999 by the robot Mars Global Surveyor spacecraft [ http://mars.jpl.nasa.gov/mgs/overvu/overview.html ] currently orbiting Mars [ http://www.nineplanets.org/mars.html ]. |
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Diamond Ring in the Sun
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Diamond Ring in the Sun |
| Explanation |
Today, earthbound skygazers can celebrate a solstice [ http://www-spof.gsfc.nasa.gov/stargaze/Sseason.htm ], a new Moon [ http://aa.usno.navy.mil/faq/docs/moon_phases.html ], the closest approach [ http://mars.jpl.nasa.gov/ ] of planet Mars since 1988 ... oh yes, and a total eclipse of the Sun, the first total solar eclipse [ http://sunearth.gsfc.nasa.gov/eclipse/TSE2001/TSE2001.html ] of the third millennium. Of course for some, today's most spectacular celestial views will be of the eclipsed Sun [ http://science.nasa.gov/headlines/y2001/ast19jun_1.htm ] from along the path of totality as the new Moon's shadow tracks across southern Africa and Madagascar [ http://www.madagascar-eclipse2001.com/eclipse_.htm ]. This picture from the August 1999 total solar eclipse captures the shimmering solar corona just as that eclipse's total phase ended, as seen from eastern Turkey. The first rays of bright sunlight shinning through edge-on [ http://sunearth.gsfc.nasa.gov/eclipse/TSE2001/TSE2001fig/ TSE2001fig08.GIF ] lunar mountains and valleys create the fleeting appearance of glistening diamonds set in a ring around the Moon's silhouette. Do you want to see today's solar eclipse? Eclipse expeditions are offering live webcasts [ http://www.bit-net.com/~pauer/eclipse01/ ]. |
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Io in True Color
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Io in True Color |
| Explanation |
The strangest moon in the Solar System [ http://www.nineplanets.org/overview.html ] is bright yellow. This picture [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02308 ], showing Io's true colors, was taken in 1999 July by the Galileo spacecraft [ http://www.jpl.nasa.gov/galileo/spacecraft.html ] currently orbiting Jupiter. Io's colors derive from sulfur [ http://chemlab.pc.maricopa.edu/periodic/S.html ] and molten silicate rock [ http://www.windows.ucar.edu/cgi- bin/tour_def/glossary/silicate_rock.html ]. The unusual surface of Io [ http://antwrp.gsfc.nasa.gov/apod/ap961029.html] is kept very young by its system of active volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap960805.html ]. The intense tidal gravity [ http://www.clupeid.demon.co.uk/tides/simple.html ] of Jupiter [ http://www.solarviews.com/eng/jupiter.htm ] stretches Io [ http://antwrp.gsfc.nasa.gov/apod/ap981016.html ] and damps wobbles caused by Jupiter's other Galilean moons [ http://www.jpl.nasa.gov/galileo/ganymede/discovery.html ]. The resulting friction [ http://www.pa.uky.edu/~phy211/Friction_book.html ] greatly heats Io [ http://antwrp.gsfc.nasa.gov/apod/ap980706.html ]'s interior, causing molten rock [ http://cmex.arc.nasa.gov/data/catalog/VolcanismOnMars/MoltenRock.html ] to explode through the surface. Io's volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap000606.html ] are so active that they are effectively turning the whole moon inside out. Some of Io [ http://www.nineplanets.org/io.html ]'s volcanic lava is so hot it glows in the dark [ http://adsabs.harvard.edu/cgi-bin/nph- bib_query?bibcode=1998Icar..135..181M ]. |
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A Piece of Interplanetary Du
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| Title |
A Piece of Interplanetary Dust |
| Explanation |
The dust that pervades our Solar System is not the dust that pervades our homes. Solar System [ http://www.nineplanets.org/overview.html ] dust comes from comets [ http://antwrp.gsfc.nasa.gov/apod/comets.html ] and asteroids [ http://antwrp.gsfc.nasa.gov/apod/asteroids.html ], whereas house dust [ http://www.ag.ohio-state.edu/~ohioline/cd-fact/0191.html ] is most likely lint or dead cells. Pictured above [ http://stardust.jpl.nasa.gov/science/sd-particle.html ] is a piece of interplanetary dust [ http://www.astro.washington.edu/brownlee/ ] caught by a high-flying U2 [ http://142.26.194.131/aerodynamics1/Appendix/Aircraft/U2.html ]-type aircraft. It likely originates in the early days of our Solar System [ http://www.fourmilab.ch/solar/solar.html ], being stored and later ejected by a passing comet [ http://antwrp.gsfc.nasa.gov/apod/ap010527.html ]. The particle is composed of glass [ http://antwrp.gsfc.nasa.gov/apod/ap000322.html ], carbon [ http://pearl1.lanl.gov/periodic/elements/6.html ], and a conglomeration of silicate mineral grains [ http://antwrp.gsfc.nasa.gov/apod/ap010523.html ]. It measures only 10 microns [ http://www.physlink.com/reference_conversion.cfm ] across, a tenth the width of a typical human hair [ http://library.thinkquest.org/26829/text-only_3-hairy_e.htm ]. NASA's STARDUST [ http://stardust.jpl.nasa.gov/cool.html ] mission, launched [ http://antwrp.gsfc.nasa.gov/apod/ap990405.html ] in 1999, is scheduled to pass through the tail of Comet Wild 2 in 2004 and return [ http://antwrp.gsfc.nasa.gov/apod/ap990218.html ] many more interstellar dust [ http://antwrp.gsfc.nasa.gov/apod/ap981121.html ] samples to Earth [ http://antwrp.gsfc.nasa.gov/apod/ap010204.html ] in 2006. |
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Mars: 3-D Dunes
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Mars: 3-D Dunes |
| Explanation |
Get out your red/blue glasses [ http://mpfwww.jpl.nasa.gov/MPF/mpf/ glasses.html ] and treat yourself to this dramatic 3-D view of sand dunes on Mars [ http://mars.jpl.nasa.gov/ ]! The field of undulating dunes is found in Nili Patera, a volcanic depression in central Syrtis Major [ http://www.orbital9.com/mars/syrtis.shtml ], the most prominent dark feature on the Red Planet [ http://marsproject.com/syrtis.htm ]. Two different images from the orbiting Mars Global Surveyor spacecraft were combined to make this stereo picture [ http://mars.jpl.nasa.gov/mgs/msss/camera/images/moc_5_24_01/ stereo/index.html ], one taken in March 1999 and the other recorded in April 2001. Sculpted by winds [ http://antwrp.gsfc.nasa.gov/apod/ap000202.html ] like the sand dunes of Earth [ http://pubs.usgs.gov/gip/deserts/eolian/ ], these particular Martian dunes show no change in shape over the time [ http://www.giss.nasa.gov/data/mars/time/ ] separating the two images, a period equivalent to about one Martian year [ http://www.jps.net/gangale/mars/chronium/ chron1.htm ]. This cropped version of the 3-D [ http://www.lpi.usra.edu/research/stereo_atlas/SS3D.HTM ] picture spans an area around 2 kilometers across. Walking, you might cover that distance in about 20 minutes. |
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Full Throttle For Deep Space
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| Title |
Full Throttle For Deep Space 1 |
| Explanation |
At full throttle the Deep Space 1 [ http://nmp.jpl.nasa.gov/ds1/index.html ] spacecraft's innovative ion drive [ http://antwrp.gsfc.nasa.gov/apod/ap981026.html ] produces about 1/50th of a pound of thrust ... a force so great that it would just about [ http://www.howstuffworks.com/question329.htm ] hold up a piece of paper on planet Earth! Still, powered by solar arrays ion propulsion systems [ http://nmp.jpl.nasa.gov/ds1/tech/sep.html ] can run continuously. For long duration space missions they ultimately win out [ http://www.jpl.nasa.gov/releases/99/discoverawards.html ] over the powerful but brief blasts of less efficient chemical rockets [ http://antwrp.gsfc.nasa.gov/apod/ap990717.html ]. Deep Space 1 is seen here [ http://www2.jpl.nasa.gov/files/images/captions/98pc1191.txt ] suspended in an assembly room, a folded solar array [ http://nmp.jpl.nasa.gov/ds1/tech/scarlet.html ] resting above the circular ion propulsion module. Already a successful technology [ http://nmp.jpl.nasa.gov/ds1/tech/index.html ] demonstrator with experimental autonomous software [ http://rax.arc.nasa.gov/ ], the spacecraft flew by asteroid 9969 Braille [ http://antwrp.gsfc.nasa.gov/apod/ap990805.html ] in July of 1999. Later that year, in November, the robot probe was nearly lost due to the failure of its wide-field star tracker camera. But engineers were able to reprogram the navigation system to utilize another on-board camera and on 28 June 2000 the ion drive was throttled up. Now, the adventures of Deep Space 1 continue [ http://science.nasa.gov/headlines/y2001/ast19sep_1.htm ]. Again steering [ http://nmp.jpl.nasa.gov/ds1/mrlog.html ] by the stars, Deep Space 1 is scheduled to rendezvous [ http://science.nasa.gov/headlines/y2001/ast19sep_1.htm ] with periodic Comet Borrelly [ http://comets.amsmeteors.org/comets/pcomets/019p.html ]"today". |
|
Pluto: The Frozen Planet
| Title |
Pluto: The Frozen Planet |
| Explanation |
The Hubble Space Telescope imaged [ http://www.ast.cam.ac.uk/HST/press/pluto.html ] Pluto and its moon Charon in 1994. Pluto [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/pluto.html ] is usually the most distant planet from the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap950813.html ] but because of its elliptic orbit Pluto crossed inside of Neptune [ http://antwrp.gsfc.nasa.gov/apod/ap950817.html ]'s orbit in 1979 and will cross back out again in 1999. Compared to the other planets, very little is known about Pluto. Pluto [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/pluto.html ] is smaller than any other planet and even smaller than several other planet's moons. From Pluto, the Sun is just a tiny point of light. Pluto [ http://dosxx.colorado.edu/plutohome.html ] is probably composed of frozen rock and ice, much like Neptune's moon Triton [ http://antwrp.gsfc.nasa.gov/apod/ap950805.html ]. Pluto has not yet been visited by a spacecraft, but a mission [ http://www.jpl.nasa.gov/pluto/ ] is being planned for the next decade. Tomorrow's picture: Our Solar System from Voyager |
|
Catching Falling Stardust
| Title |
Catching Falling Stardust |
| Explanation |
This carrot shaped track is actually little more than 5 hundredths of an inch long. It is the trail of a meteroid through a gel exposed to space in low earth orbit [ http://www-sn.jsc.nasa.gov/curator/seh/seh.htm ] by the shuttle launched EURECA (European Recoverable Carrier) spacecraft [ http://esapub.esrin.esa.it/pointtobullet/ace80.html ]. The meteoroid itself, about a thousandth of an inch in diameter, is visible where it came to rest, just beyond the tip of the carrot (far right). Chemical analyses of interplanetary dust particles [ http://spot.colorado.edu/~marscase/sd/sd-particle.html ] similar to this one suggest that some of them may be bits of comets [ http://antwrp.gsfc.nasa.gov/apod/ap950821.html ] and represent samples of material from the early stages [ http://pokey.arc.nasa.gov/division/rt_reports/fomenkova.html ] of the formation of the Solar System. NASA's Stardust mission [ http://pdcsrva.jpl.nasa.gov/stardust/home.html ], planned for launch in 1999, will attempt to directly collect dust from the tail of a comet [ http://antwrp.gsfc.nasa.gov/apod/ap950826.html ] and return it to Earth. |
|
NEAR to an Asteroid
| Title |
NEAR to an Asteroid |
| Explanation |
Excitement mounts as NASA's Near Earth Asteroid Rendezvous (NEAR) [ http://hurlbut.jhuapl.edu:80/NEAR/ ] spacecraft nears launch [ http://hurlbut.jhuapl.edu/NEAR/Education/intro/launching.html ] - currently scheduled for 3:53 ET on February 16. NEAR's mission [ http://nssdc.gsfc.nasa.gov/planetary/near.html ] is to become the first spacecraft to rendezvous with and orbit an asteroid [ http://hurlbut.jhuapl.edu:80/NEAR/Education/intro/minorobjects.html ], the asteroid designated 433 Eros. [ http://hurlbut.jhuapl.edu:80/NEAR/Education/intro/Eros.html ] After achieving Eros orbit in 1999, project plans are to explore [ http://www.eecs.wsu.edu/~hudson/asteroids.html ] the asteroid for 1 year from this premiere vantage point, perhaps approaching to within 15 miles of the surface. For comparison, above is an image [ http://www.jpl.nasa.gov/galileo/slides/slide17.html ] of the limb of asteroid Ida [ http://antwrp.gsfc.nasa.gov/apod/ap950630.html ] made by the Galileo spacecraft from a distance of about 1,500 miles, the highest resolution image of an asteroid surface [ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-asteroids.html ] - so far. It is hoped that NEAR will go far towards answering questions [ http://hurlbut.jhuapl.edu:80/NEAR/Education/NEARcurriculum.html ] about the nature and origin of near Earth asteroids. [ http://wea.mankato.mn.us/tps/neoabc.html ] These objects are thought to contain clues to the formation of the inner planets and influence the evolution of the atmosphere and life on Earth. Are asteroids and meteorites related? [ http://newproducts.jpl.nasa.gov/calender/near1.html ] Do asteroids ever strike the Earth? [ http://ccf.arc.nasa.gov/sst/main.html ] |
|
The Shadow of Phobos
| Title |
The Shadow of Phobos |
| Explanation |
Hurtling through space [ http://antwrp.gsfc.nasa.gov/apod/ap990313.html ] above the Red Planet, potato-shaped Phobos [ http://www.seds.org/nineplanets/nineplanets/ phobos.html ] completes an orbit of Mars in less than eight hours. In fact, since its orbital period is shorter than the planet's [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ marsfact.html ] rotation period, Mars-based observers [ http://www.literature.org/authors/burroughs-edgar-rice/ the-warlord-of-mars/ ] see Phobos rise in the west and set in the east - traveling from horizon to horizon in about 5 1/2 hours. These three images [ http://www.msss.com/mars_images/moc/11_1_99_phobos/ index.html ] from the Mars Global Surveyor (MGS) spacecraft [ http://ic-www.arc.nasa.gov/ic/projects/bayes-group/ Atlas/Mars/VSC/views/entrance/entrance.html ] record the oval shadow [ http://antwrp.gsfc.nasa.gov/apod/ap990830.html ] of Phobos racing over western Xanthe Terra on August 26, 1999. The area imaged is about 250 kilometers across and is seen in panels from left to right as red filter, blue filter, and combined color composite views from the MGS wide-angle camera system. The three dark spots most easily seen in the red filter image are likely small fields of dark sand dunes [ http://antwrp.gsfc.nasa.gov/apod/ap010815.html ] on crater floors. Standing in the shadow of Phobos [ http://nssdc.gsfc.nasa.gov/planetary/mars/mars_crew.html ], you would see the Martian version [ http://humbabe.arc.nasa.gov/mgcm/fun/pop.html ] of a solar eclipse! |
|
Disappearing Clouds in Carin
…
| Title |
Disappearing Clouds in Carina |
| Explanation |
This dense cloud of gas and dust is being deleted. Likely, within a few million years, the intense light from bright stars will have boiled it away completely. Stars not yet formed in the molecular cloud [ http://origins.jpl.nasa.gov/poster/bigbang3.html ]'s interior will then stop growing. The cloud has broken off of part of the greater Carina Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap010617.html ], a star forming region about 8000 light years [ http://chandra.harvard.edu/photo/cosmic_distance.html ] away. Newly formed stars are visible [ http://hubblesite.org/newscenter/archive/2000/06/image/a ] nearby, their images reddened by blue light being preferentially scattered by the pervasive dust [ http://antwrp.gsfc.nasa.gov/apod/ap010813.html ]. This unusually-colored image [ http://heritage.stsci.edu/2000/06/caption.html ] spans about two light years [ http://www.howstuffworks.com/question94.htm ] and was taken by the orbiting Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap010806.html ] in 1999. This Carina [ http://antwrp.gsfc.nasa.gov/apod/ap010717.html ] sub-cloud is particularly striking partly because its clear definition stimulates the human imagination (e.g. it could be perceived as a superhero flying through a cloud, arm up, with a saved person in tow below). |
|
An Ion Drive for Deep Space
…
| Title |
An Ion Drive for Deep Space 1 |
| Explanation |
Space travel entered the age of the ion drive in 1998 with the launch of Deep Space 1 [ http://nmp.jpl.nasa.gov/ds1/ ], a NASA mission designed primarily to test new technologies. Although the ion drive [ http://antwrp.gsfc.nasa.gov/apod/ap000831.html ] on Deep Space 1 [ http://nmp.jpl.nasa.gov/ds1/gen/rocketing_future.html ] provided acceleration [ http://physics.webplasma.com/physics02.html ] much smaller than we feel toward Earth [ http://antwrp.gsfc.nasa.gov/apod/ap010204.html ], it gradually gave the spacecraft the speed it needed to travel across our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap980517.html ]. The propulsion drive [ http://www.jpl.nasa.gov/releases/97/ioneng2.html ] worked by ionizing xenon [ http://pearl1.lanl.gov/periodic/elements/54.html ] atoms with power provided by large panels that collect sunlight. As these ions [ http://zebu.uoregon.edu/~js/glossary/ion.html ] were expelled by a strong electric field [ http://www.colorado.edu/physics/2000/waves_particles/wavpart3.html ] out the back, the spacecraft slowly gained speed. Pictured above [ http://www.jpl.nasa.gov/pictures/solar/ds1ion.html ], hot blue ions emerge from a prototype drive that was successfully tested [ http://www2.jpl.nasa.gov/files/images/captions/jpl27568.txt ] at JPL [ http://www.jpl.nasa.gov/ ] in 1997. Deep Space 1 [ http://antwrp.gsfc.nasa.gov/apod/ap981203.html ] successfully zoomed past asteroid 9969 Braille [ http://antwrp.gsfc.nasa.gov/apod/ap990805.html ] in July 1999 and then Comet Borrelly [ http://antwrp.gsfc.nasa.gov/apod/ap010926.html ] in September 2001, then obtaining the most detailed photograph [ http://antwrp.gsfc.nasa.gov/apod/ap010926.html ] ever taken of a comet nucleus. The spacecraft was retired [ http://nmp.jpl.nasa.gov/ds1/ ] in December 2001 |
|
Cassini To Venus
| Title |
Cassini To Venus |
| Explanation |
NASA's Saturn Explorer Cassini [ http://www.jpl.nasa.gov/cassini/ ] with ESA's Titan Probe Huygens [ http://www.estec.esa.nl/spdwww/huygens/html/ ] attached successfully rocketed into the skies [ http://www.ksc.nasa.gov/payload/missions/cassini/movies/movies.html ] early yesterday morning. The mighty Titan 4B Centaur rocket is seen here [ http://www-pao.ksc.nasa.gov/kscpao/captions/1997/oct/97pc1543.htm ] across the water gracefully arcing away from Launch Complex 40 [ http://www.ksc.nasa.gov/payload/missions/cassini/ ] at Cape Canaveral Air Station. Cassini, a sophisticated, bus-sized robot spacecraft [ http://www.jpl.nasa.gov/cassini/Spacecraft/ ] is now on its way ... to Venus [ http://antwrp.gsfc.nasa.gov/apod/ap971014.html ], the first planetary way point in its 7 year, 2.2 billion mile journey to Saturn. The mission profile calls [ http://www.jpl.nasa.gov/cassini/Mission/traj.html ] for Cassini to swing by Venus during April 1998 and June 1999, Earth in August 1999, and Jupiter in December 2000. During each of these "gravity assist" [ http://www.jpl.nasa.gov/basics/bsf4-1.htm#gravity ] encounters the six ton spacecraft will pick up energy needed to reach Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap970829.html ] in July 2004. Cassini's mission is the most [ http://www.jpl.nasa.gov/cassini/what/whatshot.html ] ambitious voyage of interplanetary exploration ever mounted by humanity and the Huygens Probe's planned descent to the surface of Titan [ http://antwrp.gsfc.nasa.gov/apod/ap951021.html ] will be the most distant landing ever attempted. |
|
Io in True Color
| Title |
Io in True Color |
| Explanation |
The strangest moon in the Solar System [ http://www.nineplanets.org/overview.html ] is bright yellow. This picture [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02308 ], showing Io's true colors, was taken in 1999 July by the Galileo spacecraft [ http://www.jpl.nasa.gov/galileo/spacecraft.html ] that orbited Jupiter from 1995 to 2003. Io's colors derive from sulfur [ http://chemlab.pc.maricopa.edu/periodic/S.html ] and molten silicate rock [ http://www.windows.ucar.edu/cgi- bin/tour_def/glossary/silicate_rock.html ]. The unusual surface of Io [ http://antwrp.gsfc.nasa.gov/apod/ap961029.html ] is kept very young by its system of active volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap960805.html ]. The intense tidal gravity [ http://www.clupeid.demon.co.uk/tides/simple.html ] of Jupiter [ http://www.solarviews.com/eng/jupiter.htm ] stretches Io [ http://antwrp.gsfc.nasa.gov/apod/ap981016.html ] and damps wobbles caused by Jupiter's other Galilean moons [ http://www.jpl.nasa.gov/galileo/ganymede/discovery.html ]. The resulting friction [ http://www.pa.uky.edu/~phy211/Friction_book.html ] greatly heats Io [ http://antwrp.gsfc.nasa.gov/apod/ap980706.html ]'s interior, causing molten rock [ http://cmex.arc.nasa.gov/data/catalog/VolcanismOnMars/MoltenRock.html ] to explode through the surface. Io's volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap000606.html ] are so active that they are effectively turning the whole moon inside out. Some of Io [ http://www.nineplanets.org/io.html ]'s volcanic lava is so hot it glows in the dark [ http://adsabs.harvard.edu/cgi-bin/nph- bib_query?bibcode=1998Icar..135..181M ]. |
|
Cassini To Venus
| Title |
Cassini To Venus |
| Explanation |
Saturn Orbiter Cassini [ http://saturn.jpl.nasa.gov/home/index.cfm ] with Titan Probe Huygens [ http://saturn.jpl.nasa.gov/overview/huygens-probe.cfm ] attached rocketed into [ http://www.ksc.nasa.gov/payload/missions/cassini/movies/ movies.html ] early morning skies on October 15, 1997. The mighty Titan 4B Centaur rocket is seen here [ http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=1004 ] across the water, arcing away from Launch Complex 40 at Cape Canaveral [ http://www.astronautix.com/sites/ capveral.htm ] Air Station. Cassini, a sophisticated robot spacecraft [ http://saturn.jpl.nasa.gov/spacecraft/index.cfm ] was actually headed toward inner planet Venus [ http://antwrp.gsfc.nasa.gov/apod/ap020929.html ], the first way point in its 7 year, 2.2 billion mile interplanetary journey to Saturn. In fact, Cassini swung by [ http://saturn.jpl.nasa.gov/mission/ gravity-assists.cfm ] Venus during April 1998 and June 1999, Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990826.html ] in August 1999, and Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap031114.html ] in December 2000. During each of these "gravity assist" [ http://www.jpl.nasa.gov/basics/ bsf4-1.htm#gravity ] encounters the six ton spacecraft picked up speed, reaching Saturn [ http://www.nasa.gov/mission_pages/cassini/media/ cassini-063004-soi.html ] only three days ago. Cassini is now orbiting the ringed gas giant, with the Huygens Probe scheduled to separate from the spacecraft in December. The probe's descent to the surface [ http://www.space.com/scienceastronomy/ titan_huygens_031014.html ] of Saturn's large moon Titan [ http://www.nineplanets.org/titan.html ] will be the most distant landing [ http://antwrp.gsfc.nasa.gov/apod/ap011013.html ] ever attempted. |
|
Bright Comet SOHO
| Title |
Bright Comet SOHO |
| Explanation |
Discovered this month [ http://antwrp.gsfc.nasa.gov/apod/ap980520.html ] with an orbiting solar observatory, bright Comet SOHO [ http://encke.jpl.nasa.gov/index.html ] has now emerged from the Sun's glare. This telephoto picture of the new naked-eye comet [ http://www.ozemail.com.au/~mhorn/soho.html ] was taken by astrophotographer Michael Horn [ http://www.ozemail.com.au/~mhorn/photos.html ] after sunset in the western twilight above Lake Samsonvale, Brisbane, Australia on May 18. The comet is seen [ http://www.astro.uio.no/~bgranslo/soho.html ] in the constellation Orion [ http://www.astro.wisc.edu/~dolan/constellations/ constellations/Orion.html ]. Its long lovely tail [ http://antwrp.gsfc.nasa.gov/apod/ap960502.html ] stretches nearly 5 degrees to the bright star Bellatrix [ http://www.astro.wisc.edu/~dolan/constellations/hr/1790.html ], near the top of the image. For Southern Hemisphere comet watchers, views of Comet SOHO (1998J1) will improve as this month draws to a close and the comet climbs to the south and east on its journey outward bound. In February 1999, NASA plans to launch the Stardust mission [ http://stardust.jpl.nasa.gov/top.html ] to fly close to a comet [ http://stardust.jpl.nasa.gov/news/ ] and return samples of dust from a comet's tail [ http://stardust.jpl.nasa.gov/comets/wild2.html ]. |
|
The Dunes Of Mars
| Title |
The Dunes Of Mars |
| Explanation |
The North Pole of Mars [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA00009 ] is ringed by a "sea of sand dunes". For Mars' Northern Hemisphere, Spring began in mid July [ http://www.msss.com/http/ps/seasons/seasons.html ] and increased sunlight is now shrinking the polar cap revealing the wind-swept [ http://www.nasm.edu:2020/SII/EDU/CURRIC/windexer.html ] dunes to the cameras onboard the Mars Global Surveyor [ http://mars.jpl.nasa.gov/mgs/sci/CDsampler/browse/index.htm ] spacecraft. North is up in this recently released [ http://www.msss.com/mars/global_surveyor/camera/images/ 8_7_98_n_erg_rel/index.html ] close-up which covers a region about 1.2 miles across at 77 degrees Northern Martian Latitude [ http://www-pdsimage.wr.usgs.gov/PDS/public/mapmaker/mapmkr.htm ]. These dunes have been formed by winds [ http://www.palomar.edu/Wayne/ww0704.htm ] generally blowing from the Southwest and are still covered with scattered white patches of carbon dioxide frost. Near the end of January 1999 Summer [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/ m09_mtvs4297_47.html ] will begin and offer even clearer views of Northern dunes of Mars [ http://www.literature.org/Works/Edgar-Rice-Burroughs/ warlord-of-mars/chapter-01.html ]. |
|
The North Pole Of Mars
| Title |
The North Pole Of Mars |
| Explanation |
The North Pole of Mars [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA00009 ] is capped by layers likely consisting of ice and dust deposited over millions of years. Imaged on September 12 - early Spring for Northern Mars [ http://www.msss.com/http/ps/seasons/seasons.html ] - by the Mars Global Surveyor's camera, this synthesized wide-angle color view [ http://mars.jpl.nasa.gov/mgs/msss/camera/images/ 9_19_98_endSPO2_rel/9_19_98_npole_rel/index.html ] shows the rippled, eroded polar terrain covered with pinkish seasonal carbon dioxide frost. Dark areas bordering the polar cap are fields of sand dunes [ http://antwrp.gsfc.nasa.gov/apod/ap980814.html ]. This is the last picture scheduled to be taken by Surveyor's camera until it resumes operation in late March 1999. Over the past year of operation, the camera has taken about 2,000 pictures of Mars [ http://mars.jpl.nasa.gov/mgs/msss/camera/images/index.html ]. Meanwhile, the spacecraft will begin [ http://mars.jpl.nasa.gov/mgs/press/press-9-22-98.html ] its second round of aerobraking to achieve [ http://antwrp.gsfc.nasa.gov/apod/ap970911.html ] a circularized martian mapping orbit [ http://observe.ivv.nasa.gov/nasa/education/reference/ orbits/orbit1.html ]. |
|
An Ion Drive for Deep Space
…
| Title |
An Ion Drive for Deep Space 1 |
| Explanation |
Space travel entered the age of the ion drive Saturday [ http://www.jpl.nasa.gov/ds1news/ ] with the launch of Deep Space 1 [ http://nmp.jpl.nasa.gov/ds1/ ], a NASA mission designed primarily to test new technologies. Deep Space 1 [ http://nmp.jpl.nasa.gov/ds1/gen/rocketing_future.html ] is bound for asteroid [ http://www.seds.org/nineplanets/nineplanets/asteroids.html ] 1992 KD [ http://cfa-www.harvard.edu/iauc/05500/05531.html ] in July 1999. Although the ion drive [ http://nmp.jpl.nasa.gov/ds1/tech/ionpropfaq.html ] on Deep Space 1 provides acceleration [ http://jersey.uoregon.edu/vlab/page2.html ] much smaller than we feel toward Earth [ http://antwrp.gsfc.nasa.gov/apod/ap971026.html ], it will gradually give the spacecraft the speed it needs to travel across our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap980517.html ]. The propulsion drive [ http://www.jpl.nasa.gov/releases/97/ioneng2.html ] works by ionizing Xenon [ http://cst.lanl.gov/CST/imagemap/periodic/54.html ] atoms with power provided by large panels that collect sunlight. As these ions [ http://zebu.uoregon.edu/~js/glossary/ion.html ] are expelled by a strong electric field [ http://ericir.syr.edu/Projects/Newton/12/Lessons/electric.html ] out the back, the spacecraft slowly gains speed. Pictured above [ http://www.jpl.nasa.gov/pictures/solar/ds1ion.html ], hot blue ions emerge from a prototype drive that was successfully tested [ http://www2.jpl.nasa.gov/files/images/captions/jpl27568.txt ] last year at JPL [ http://www.jpl.nasa.gov/ ]. |
|
The Shadow of Phobos
| Title |
The Shadow of Phobos |
| Explanation |
Hurtling through space [ http://antwrp.gsfc.nasa.gov/apod/ap990313.html ]above the Red Planet, potato-shaped Phobos [ http://www.seds.org/nineplanets/nineplanets/ phobos.html ] completes an orbit of Mars in less than eight hours. In fact, since its orbital period is shorter than the planet's [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ marsfact.html ] rotation period, Mars-based observers [ http://photojournal.jpl.nasa.gov/catalog/PIA06337 ] see Phobos rise in the west and set in the east - traveling from [ http://photojournal.jpl.nasa.gov/catalog/PIA06340 ] horizon to horizon in about 5 1/2 hours. These three images [ http://www.msss.com/mars_images/moc/11_1_99_phobos/ index.html ] from the Mars Global Surveyor (MGS) spacecraft [ http://ic-www.arc.nasa.gov/ic/projects/bayes-group/ Atlas/Mars/VSC/views/entrance/entrance.html ] record the oval shadow [ http://antwrp.gsfc.nasa.gov/apod/ap990830.html ] of Phobos racing over western Xanthe Terra on August 26, 1999. The area imaged is about 250 kilometers across and is seen in panels from left to right as red filter, blue filter, and combined color composite views from the MGS wide-angle camera system. The three dark spots most easily seen in the red filter image are likely small fields of dark sand dunes [ http://antwrp.gsfc.nasa.gov/apod/ap010815.html ] on crater floors. Standing in the shadow of Phobos [ http://cmex-www.arc.nasa.gov/CMEX/index.html ], you would see the Martian version [ http://www.literature.org/authors/burroughs-edgar-rice/ the-warlord-of-mars/ ] of a solar eclipse! |
|
The Shadow Of Phobos
| Title |
The Shadow Of Phobos |
| Explanation |
Hurtling through space [ http://antwrp.gsfc.nasa.gov/apod/ap990313.html ] above the Red Planet, potato-shaped Phobos [ http://www.seds.org/nineplanets/nineplanets/phobos.html ] completes an orbit of Mars in less than eight hours. In fact, since its orbital period is shorter than the planet's [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html ] rotation period, Mars-based observers [ http://www.literature.org/authors/burroughs-edgar-rice/ the-warlord-of-mars/ ] see Phobos rise in the west and set in the east - traveling from horizon to horizon in about 5 1/2 hours. These three images [ http://www.msss.com/mars_images/moc/11_1_99_phobos/index.html ] from the Mars Global Surveyor (MGS) spacecraft [ http://ic-www.arc.nasa.gov/ic/projects/bayes-group/ Atlas/Mars/VSC/views/entrance/entrance.html ] record the oval shadow [ http://antwrp.gsfc.nasa.gov/apod/ap990830.html ] of Phobos racing over western Xanthe Terra on August 26, 1999. The area imaged is about 250 kilometers across and is seen in panels from left to right as red filter, blue filter, and combined color composite views from the MGS wide-angle camera system. The three dark spots most easily seen in the red image are likely [ http://www.msss.com/mars_images/moc/11_1_99_phobos/index.html ] small fields of dark sand dunes on crater floors. Standing in the shadow of Phobos [ http://nssdc.gsfc.nasa.gov/planetary/mars/mars_crew.html ], you would see the Martian version [ http://humbabe.arc.nasa.gov/mgcm/fun/pop.html ] of a solar eclipse! |
|
Ant nebula
| Title |
Ant nebula |
| Description |
A new Hubble Space Telescope image of a celestial object called the Ant Nebula may shed new light on the future demise of our Sun. The image is available at http://www.jpl.nasa.gov/pictures/wfpc . The nebula, imaged on July 20, 1997, and June 30, 1998, by Hubble's Wide Field and Planetary Camera 2, was observed by Drs. Raghvendra Sahai and John Trauger of NASA's Jet Propulsion Laboratory, Pasadena, Calif., Bruce Balick of the University of Washington in Seattle, and Vincent Icke of Leiden University in the Netherlands. JPL designed and built the camera. The Ant Nebula, whose technical name is Mz3, resembles the head and thorax of an ant when observed with ground-based telescopes. The new Hubble image, with 10 times the resolution revealing 100 times more detail, shows the "ant's" body as a pair of fiery lobes protruding from a dying, Sun- like star. The Ant Nebula is located between 3,000 and 6,000 light years from Earth in the southern constellation Norma. The image challenges old ideas about what happens to dying stars. This observation, along with other pictures of various remnants of dying stars called planetary nebulae, shows that our Sun's fate will probably be much more interesting, complex and dramatic than astronomers previously believed. Although the ejection of gas from the dying star in the Ant Nebula is violent, it does not show the chaos one might expect from an ordinary explosion, but instead shows symmetrical patterns. One possibility is that the central star has a closely orbiting companion whose gravitational tidal forces shape the outflowing gas. A second possibility is that as the dying star spins, its strong magnetic fields are wound up into complex shapes like spaghetti in an eggbeater. Electrically charged winds, much like those in our Sun's solar wind but millions of times denser and moving at speeds up to 1,000 kilometers per second (more than 600 miles per second) from the star, follow the twisted field lines on their way out into space. The Space Telescope Science Institute, Baltimore, Md., manages space operations for the Hubble Space Telescope for NASA's Office of Space Science, Washington, D.C. The Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract with NASA's Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. JPL is a division of the California Institute of Technology in Pasadena. Additional information about the Hubble Space Telescope is available at http://www.stsci.edu . More information about the Wide Field and Planetary Camera 2 is available at http://wfpc2.jpl.nasa.gov. |
| Date |
12.10.1999 |
|
N44C nebula
| Title |
N44C nebula |
| Description |
Resembling the hair in Botticelli's famous portrait of the birth of Venus, an image from NASA's Hubble Space Telescope has captured softly glowing filaments streaming from hot young stars in a nearby nebula. The image, presented by the Hubble Heritage Project, was taken in 1996 by Hubble's Wide Field and Planetary Camera 2, designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. The image is available online at http://heritage.stsci.edu , http://oposite.stsci.edu/pubinfo/pr/2002/12 orhttp://www.jpl.nasa.gov/images/wfpc . On the top right of the image is a source of its artistic likeness, a network of nebulous filaments surrounding the Wolf-Rayet star. This type of rare star is characterized by an exceptionally vigorous "wind" of charged particles. The shock of the wind colliding with the surrounding gas causes the gas to glow. The Wolf-Rayet star is part of N44C, a nebula of glowing hydrogen gas surrounding young stars in the Large Magellanic Cloud. Visible from the Southern Hemisphere, the Large Magellanic Cloud is a small companion galaxy to the Milky Way. What makes N44C peculiar is the temperature of the star that illuminates it. The most massive stars -- those that are 10 to 50 times more massive than the Sun -- have maximum temperatures of 30,000 to 50,000 degrees Celsius (54,000 to 90,000 degrees Fahrenheit). The temperature of this star is about 75,000 degrees Celsius (135,000 degrees Fahrenheit). This unusually high temperature may be due to a neutron star or black hole that occasionally produces X-rays but is now inactive. N44C is part of a larger complex that includes young, hot, massive stars, nebulae, and a "superbubble" blown out by multiple supernova explosions. Part of the superbubble is seen in red at the very bottom left of the Hubble image. The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. |
| Date |
12.03.1999 |
|
Cold Hole Over Jupiter's Pol
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| Title |
Cold Hole Over Jupiter's Pole |
| Description |
Observations with two NASA telescopes show that Jupiter has an arctic polar vortex similar to a vortex over Earth's Antarctica that enables depletion of Earth's stratospheric ozone. These composite images of Jupiter's north polar region from the Hubble Space Telescope (right) and the Infrared Telescope Facility (left) show a quasi-hexagonal shape that extends vertically from the stratosphere down into the top of the troposphere. A sharp temperature drop, compared to surrounding air masses, creates an eastward wind that tends to keep the polar atmosphere, including the stratospheric haze, isolated from the rest of the atmosphere. The linear striations in the composite projections are artifacts of the image processing. The area closest to the pole has been omitted because it was too close to the edge of the planet in the original images to represent the planet reliably. The composite on the right combines images from the Wide Field and Planetary Camera 2 of the Hubble Space Telescope taken at a wavelength of 890 nanometers, which shows stratospheric haze particles. The sharp boundary and wave-like structure of the haze layer suggest a polar vortex and a similarity to Earth's stratospheric polar clouds. Images of Jupiter's thermal radiation clinch that identification. The composite on the left, for example, is made from images taken with Jet Propulsion Laboratory's Mid-Infrared Large-Well Imager at NASA's Infrared Telescope Facility at a wavelength of 17 microns. It shows polar air mass that is 5 to 6 degrees Celsius (9 to 10 degrees Fahrenheit) colder than its surroundings, with the same border as the stratospheric haze. Similar observations at other infrared wavelengths show the cold air mass extends at least as high as the middle stratosphere down to the top of the troposphere. These images were taken Aug. 11 through Aug. 13, 1999, near a time when Jupiter's north pole was most visible from Earth. Other Infrared Telescope Facility images at frequencies sensitive to the polar haze were taken at frequent intervals from June to October 1999. They show that the quasi-hexagonal structure rotates slowly eastward at 1.2 degrees of longitude per day, a rate consistent with the average wind speeds measured from movement of visible clouds. Scientists studying the Earth's atmosphere are interested in these results because Jupiter's atmosphere provides a natural laboratory in which models of the polar vortex phenomenon can be studied under different conditions - for example, without the interference of topography. Of particular interest but yet unknown is how deep into Jupiter's troposphere the phenomenon extends. The answer to this question might be supplied by instrumentation on a polar orbiter mission at Jupiter. These images were taken as part of a program to support NASA's Galileo spacecraft reconnaissance of Jupiter. The Infrared Telescope Facility is on the summit of Hawaii's Mauna Kea and is operated by the University of Hawaii under a, cooperative agreement with NASA. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The telescope is managed by the Space Telescope Science Institute, Baltimore, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The California Institute of Technology, Pasadena manages JPL for NASA. |
| Date |
10.08.2002 |
|
Rotten Egg Nebula
| Title |
Rotten Egg Nebula |
| Description |
Violent gas collisions that produced supersonic shock fronts in a dying star are seen in a new, detailed image from NASA's Hubble Space Telescope. The picture, taken by Hubble's Wide Field and Planetary Camera 2, is online at http://www.jpl.nasa.gov/images/wfpc . The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Stars like our Sun will eventually die and expel most of their material outward into shells of gas and dust. These shells eventually form some of the most beautiful objects in the universe, called planetary nebulae."This new image gives us a rare view of the early death throes of stars like our Sun. For the first time, we can see phenomena leading to the formation of planetary nebulae. Until now, this had only been predicted by theory, but had never been seen directly," said Dr. Raghvendra Sahai, research scientist and member of the science team at JPL for the Wide Field and Planetary Camera 2. The object is sometimes called the Rotten Egg Nebula, because it contains a lot of sulphur, which would produce an awful odor if one could smell in space. The object is also known as the Calabash Nebula or by the technical name OH231.8+4.2. The densest parts of the nebula are composed of material ejected recently by the central star and accelerated in opposite directions. This material, shown as yellow in the image, is zooming away at speeds up to one and a half million kilometers per hour (one million miles per hour). Most of the star's original mass is now contained in these bipolar gas structures. A team of Spanish and American astronomers used NASA's Hubble Space Telescope to study how the gas stream rams into the surrounding material, shown in blue. They believe that such interactions dominate the formation process in planetary nebulae. Due to the high speed of the gas, shock-fronts are formed on impact and heat the surrounding gas. Although computer calculations have predicted the existence and structure of such shocks for some time, previous observations have not been able to prove the theory. This new Hubble image used filters that only let through light from ionized hydrogen and nitrogen atoms. Astronomers were able to distinguish the warmest parts of the gas heated by the violent shocks and found that they form a complex double-bubble shape. The bright yellow-orange colors in the picture show how dense, high-speed gas is flowing from the star, like supersonic speeding bullets ripping through a medium in opposite directions. The central star itself is hidden in the dusty band at the center. Much of the gas flow observed today seems to stem from a sudden acceleration that took place only about 800 years ago. The astronomers believe that 1,000 years from now, the Calabash Nebula will become a fully developed planetary nebula, like a butterfly emerging from its cocoon. The Calabash Nebula is 1.4 light years (more than 8 trillion miles) long and located some 5,000 light years (2,900 trillion, miles) from Earth in the constellation Puppis. The image was taken in December 2000 by the Wide Field and Planetary Camera 2. The image was originally released by the Hubble European Space Agency Information Centre, with a website at http://sci.esa.int/hubble. Additional information about the Hubble Space Telescope is online at http://www.stsci.edu . More information about the Wide Field and Planetary Camera 2 is at http://wfpc2.jpl.nasa.gov . Other scientists on the team include Valentin Bujarrabal and Javier Alcolea of Observatorio Astronomico Nacional, Spain, and Carmen Sanchez Contreras of JPL. The Space Telescope Science Institute, Baltimore, Md., manages space operations for Hubble for NASA's Office of Space Science, Washington, D.C. The institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. JPL is a division of the California Institute of Technology in Pasadena. |
| Date |
12.02.1999 |
|
Doradus Nebula
| Title |
Doradus Nebula |
| Description |
A panoramic view of a vast, sculpted area of gas and dust where thousands of stars are being born has been captured by NASA's Hubble Space Telescope. The image, taken by Hubble's Wide Field and Planetary Camera 2, is online at http://oposite.stsci.edu/pubinfo/pr/2001/21 and http://www.jpl.nasa.gov/images/wfpc . The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. The photo offers an unprecedented, detailed view of the entire inner region of the fertile, star-forming 30 Doradus Nebula. The mosaic picture shows that ultraviolet radiation and high-speed material unleashed by the stars in the cluster, called R136 (the large blue blob left of center), are weaving a tapestry of creation and destruction, triggering the collapse of looming gas and dust clouds and forming pillar-like structures that incubate newborn stars. The 30 Doradus Nebula is in the Large Magellanic Cloud, a satellite galaxy of the Milky Way located 170,000 light-years from Earth. Nebulas like 30 Doradus are signposts of recent star birth. High-energy ultraviolet radiation from young, hot, massive stars in R136 causes surrounding gaseous material to glow. Previous Hubble telescope observations showed that R136 contains several dozen of the most massive stars known, each about 100 times the mass of the Sun and about 10 times as hot. These stellar behemoths formed about 2 million years ago. The stars in R136 produce intense "stellar winds," streams of material traveling at several million miles an hour. These winds push the gas away from the cluster and compress the inner regions of the surrounding gas and dust clouds (seen in the image as the pinkish material). The intense pressure triggers the collapse of parts of the clouds, producing a new star formation around the central cluster. Most stars in the nursery are not visible because they are still encased in cocoons of gas and dust. This mosaic image of 30 Doradus consists of five overlapping pictures taken between January 1994 and September 2000 by the Wide Field and Planetary Camera 2. Several color filters enhance important details in the stars and the nebula. Blue corresponds to the hot stars. The greenish color denotes hot gas energized by the central cluster of stars. Pink depicts the glowing edges of the gas and dust clouds facing the cluster, which are being bombarded by winds and radiation. Reddish-brown represents the cooler surfaces of the clouds, which are not receiving direct radiation from the central cluster. Additional information about the Hubble Space Telescope is at http://www.stsci.edu . More information about the Wide Field and Planetary Camera 2 is at http://wfpc2.jpl.nasa.gov . The Space Telescope Science Institute, Baltimore, Md., manages space operations for Hubble for NASA's Office of Space Science, Washington, D.C. The institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight, Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. JPL is a division of the California Institute of Technology in Pasadena. |
| Date |
12.01.1999 |
|
Edge-on Galaxy
| Title |
Edge-on Galaxy |
| Description |
NASA's Hubble Space Telescope has imaged an unusual edge-on galaxy, revealing remarkable details of its warped dusty disc and showing how colliding galaxies trigger the birth of new stars. The image, taken by Hubble's Wide Field and Planetary Camera 2 (WFPC2), is online at http://heritage.stsci.edu and http://www.jpl.nasa.gov/images/wfpc. The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. During observations of the galaxy, the camera passed a milestone, taking its 100,000th image since shuttle astronauts installed it in Hubble in 1993. The dust and spiral arms of normal spiral galaxies, like our Milky Way, look flat when seen edge- on. The new image of the galaxy ESO 510-G13 shows an unusual twisted disc structure, first seen in ground-based photographs taken at the European Southern Observatory in Chile. ESO 510-G13 lies in the southern constellation Hydra, some 150 million light-years from Earth. Details of the galaxy's structure are visible because interstellar dust clouds that trace its disc are silhouetted from behind by light from the galaxy's bright, smooth central bulge. The strong warping of the disc indicates that ESO 510-G13 has recently collided with a nearby galaxy and is in the process of swallowing it. Gravitational forces distort galaxies as their stars, gas, and dust merge over millions of years. When the disturbances die out, ESO 510-G13 will be a single galaxy. The galaxy's outer regions, especially on the right side of the image, show dark dust and bright clouds of blue stars. This indicates that hot, young stars are forming in the twisted disc. Astronomers believe star formation may be triggered when galaxies collide and their interstellar clouds are compressed. The Hubble Heritage Team used WFPC2 to observe ESO 510-G13 in April 2001. Pictures obtained through blue, green, and red filters were combined to make this color-composite image, which emphasizes the contrast between the dusty spiral arms, the bright bulge, and the blue star-forming regions. Additional information about the Hubble Space Telescope is online at http://www.stsci.edu. More information about the Wide Field and Planetary Camera 2 is at http://wfpc2.jpl.nasa.gov. The Space Telescope Science Institute, Baltimore, Md., manages space operations for Hubble for NASA's Office of Space Science, Washington, D.C. The institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. Hubble is a project of international cooperation between NASA and the European Space Agency. JPL is a division of the California Institute of Technology in Pasadena. |
| Date |
12.30.1999 |
|
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