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Astronomers Find Smallest Ex
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| Title |
Astronomers Find Smallest Extrasolar Planet Yet Around Normal Star |
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Announcing Comet Hale-Bopp
| Title |
Announcing Comet Hale-Bopp |
| Explanation |
The pictured fuzzy patch may become one of the most spectacular comets this century. Although it is very hard to predict how bright a comet [ http://seds.lpl.arizona.edu/billa/tnp/comets.html ] will become, Comet Hale-Bopp [ http://encke.jpl.nasa.gov/hale_bopp_info.html ], named for its discoverers [ http://encke.jpl.nasa.gov/hale_bopp/discoverers.html ], was spotted farther from the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap950813.html ] than any previous comet - a good sign that it could become very bright, easily visible to the naked eye. This picture was taken on July 25th 1995, only two days after its discovery. A comet [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/comet.html ] bright enough to see without a telescope occurs only about once a decade. The large coma [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#coma ] and long tail [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#comet ] of bright comets are so unusual and impressive that they have been considered omens of change by many cultures. A comet does not streak by in few seconds - but it may change its position and structure noticeably from night to night. Tomorrow's picture: An Orbiting Iceberg |
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Clouds and the Moon Move to
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| Title |
Clouds and the Moon Move to Block the Sun |
| Explanation |
High above a small church near Vienna, Austria [ http://www.cia.gov/cia/publications/factbook/geos/au.html ], clouds and the Moon vied for position in front of the Sun. Such was the case on the ground late last month during a partial eclipse of the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap030606.html ] visible throughout Europe and Asia [ http://www.askasia.org/image/maps/asia.htm ]. Nearing the farthest part of its orbit [ http://www.windows.ucar.edu/tour/link=/the_universe/uts/moon1.html ] around the Earth [ http://www.nineplanets.org/earth.html ], the Moon's angular size [ http://antwrp.gsfc.nasa.gov/apod/ap010218.html ] was too small to block [ http://www.earthview.com/tutorial/causes.htm ] the entire Sun, a situation that would have resulted in a total solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap010408.html ]. The next solar eclipse visible from Earth will occur on November 23. Although a total eclipse [ http://www.exploratorium.edu/eclipse/ ] will be visible only from parts of Antarctica [ http://antwrp.gsfc.nasa.gov/apod/ap991116.html ], parts of the Sun will momentarily disappear for observers across Australia [ http://www.cia.gov/cia/publications/factbook/geos/as.html ], New Zealand [ http://www.cia.gov/cia/publications/factbook/geos/nz.html ], and the southernmost tip of South America [ http://www.infoplease.com/atlas/southamerica.html ]. |
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Star Trails Over Vienna
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Star Trails Over Vienna |
| Explanation |
As the Earth spins on its axis, the sky seems to rotate around us. This motion, called diurnal motion [ http://antwrp.gsfc.nasa.gov/apod/ap010110.html ], produces the beautiful concentric trails traced by stars during time exposures. In the middle of the picture is the North Celestial Pole [ http://solar.physics.montana.edu/YPOP/Classroom/Lessons/Sundials/skydome.html ] (NCP), easily identified as the point in the sky at the center of all the star trail arcs. The star Polaris [ http://antwrp.gsfc.nasa.gov/apod/ap991006.html ], commonly known as the North Star [ http://en.wikipedia.org/wiki/North_star ], made the very short bright circle near the NCP. Full circle star trails are pictured over Vienna, Austria [ http://www.cia.gov/cia/publications/factbook/geos/au.html ]. This image [ http://homepage.univie.ac.at/peter.wienerroither/ pwafoxe.htm ], a relatively short exposure followed by a digital trick, could not have been taken during a single night because 24-hours are needed for one full rotation, and the Sun is sure [ http://antwrp.gsfc.nasa.gov/apod/ap050503.html ] to dominate the frame at some time. |
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Space Radar Image of Oetzal,
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PIA01704
Sol (our sun)
| Title |
Space Radar Image of Oetzal, Austria |
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Space radar image of Mount E
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PIA01301
Sol (our sun)
Imaging Radar
| Title |
Space radar image of Mount Everest |
| Original Caption Released with Image |
These are two comparison images of Mount Everest and its surroundings, along the border of Nepal and Tibet. The peak of Mount Everest, the highest elevation on Earth at 8,848 meters (29,028 feet), can be seen near the center of each image. The image at the top was acquired through thick cloud cover by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 16, 1994. The image on the bottom is an optical photograph taken by the Endeavour crew under clear conditions during the second flight of SIR-C/X-SAR on October 10, 1994. Both images show an area approximately 70 kilometers by 38 kilometers (43 miles by 24 miles) that is centered at 28.0 degrees north latitude and 86.9 degrees east longitude. North is toward the upper left. The colors in the radar image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received), green represents the L-band (horizontally transmitted and vertically received), blue represents the C-band (horizontally transmitted and vertically received). Radar illumination is from the top of the frame. The optical photograph has been geometrically adjusted to better match the area shown in the radar image. Many features of the Himalayan terrain are visible in both images. Snow covered areas appear white in the optical photograph while the same areas appear bright blue in the radar image. The radar image was taken in early spring and shows deep snow cover, while the optical photograph was taken in late summer and shows minimum snow cover. The curving and branching features seen in both images are glaciers. The two wavelengths and multiple polarizations of the SIR-C radar are sensitive to characteristics of the glacier surfaces that are not detected by conventional photography, such as the ice roughness, water content and stratification. For this reason, the glaciers show a variety of colors in the radar image (blue, purple, red, yellow, white) but only appear as gray or white in the photograph. Field data from other SIR-C/X-SAR test sites, such as the Alpine glaciers of Austria, are being used to help interpret data from remote regions like Mount Everest. |
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Aerosols over Central and Ea
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PIA04325
Sol (our sun)
Multi-angle Imaging SpectroR
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| Title |
Aerosols over Central and Eastern Europe |
| Original Caption Released with Image |
Particulate air pollution is a complex mixture of particles of varying origins and compositions. Determining the type and abundance of tiny airborne particles, known as aerosols, is needed for monitoring air quality and for understanding climate change. During the last weeks of March 2003, unusually high and widespread aerosol pollution was detected over Europe by several satellite-borne instruments. The Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard NASA's Terra satellite determines aerosol amount and information about particle properties by examining the variation in scene brightness at different view angles. These images and data products illustrate the amount of aerosols on two dates over parts of Central and Eastern Europe, from the Baltic Sea in the north to the Adriatic Sea in the south. Two groups of three panels are shown. Within each group, the left and center views are natural-color images from MISR's vertical-viewing (nadir) and most obliquely forward-viewing cameras, respectively, and the right-hand panel is a map of retrieved aerosol amount, parameterized by a quantity called the optical depth. A color scale is used to represent this quantity, and high aerosol amount is indicated by yellow or green pixels, and clearer skies are indicated by blue pixels. The left-hand group of panels is comprised of data acquired on February 23, 2003, when most of the land area was still partially frozen. The right-hand group of panels portrays the same area about one month later, on March 27. The nadir camera enables surface features to stand out most clearly, whereas MISR's oblique cameras enhance sensitivity to even thin layers of aerosols. In the March image, the only strong indications of haze from the nadir view are the thin tendrils of grayish pixels over the dark waters of the Baltic Sea. Although aerosols are conventionally difficult to discern over bright surfaces, MISR is able to produce an aerosol abundance map for both the earlier snow-covered scene and for the later date, though fewer successful retrievals were obtained in the winter data. Skies were relatively clear in the earlier view, and the high optical depths implied by the red pixels are probably blunders due either to the homogeneity of the underlying snow-covered surface or the presence of unscreened clouds. In contrast, the March data show a thick haze over most of the lower-elevation parts of the observed area. Optical depths are relatively lower over the Julian Alps and the mountains of western Croatia (just north of the Adriatic), whereas higher abundances are observed to the north of the mountains and over eastern Croatia. There is a gradual transition from higher optical depths in western Poland to lower optical depths in Lithuania and along the eastern coast of the Baltic. Higher optical depths are also indicated over much of Hungary, Slovakia and eastern Austria. Places where clouds or other factors precluded an aerosol retrieval are otherwise shown in, dark gray. An overview [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=8637 ] of the haze extent and meteorological conditions for March 28, 2003 is also available from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) sensor. The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. These data products were generated from a portion of the imagery acquired during Terra orbits 16937 and 17403. The panels cover an area of about 380 kilometers x 1775 kilometers, and use data from blocks 43 to 55 within World Reference System-2 path 190. MISR was built and is managed by NASA's Jet Propulsion Laboratory,Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center,Greenbelt, MD. JPL is a division of the California Institute ofTechnology. |
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Space Radar Image of Oetzal,
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PIA01760
Sol (our sun)
| Title |
Space Radar Image of Oetzal, Austria |
| Original Caption Released with Image |
Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.V.(DLR), the major partner in science, operations and data processing of X-SAR., This is a digital elevation model that was geometrically coded directly onto an X-band seasonal change image of the Oetztal supersite in Austria. The image is centered at 46.82 degrees north latitude and 10.79 degrees east longitude. This image is located in the Central Alps at the border between Switzerland, Italy and Austria, 50 kilometers (31 miles) southwest of Innsbruck. It was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture aboard the space shuttle Endeavour on April 14, 1994 and on October 5, 1994. It was produced by combining data from these two different data sets. Data obtained in April is green, data obtained in October appears in red and blue, and was used as an enhancement based on the ratio of the two data sets. Areas with a decrease in backscatter from April to October appear in light blue (cyan), such as the large Gepatschferner glacier seen at the left of the image center, and most of the other glaciers in this view. A light blue hue is also visible at the east border of the dark blue Lake Reschensee at the upper left side. This shows a significant rise in the water level. Magenta represents areas with an increase of backscatter from April 10 to October 5. Yellow indicates areas with high radar signal response during both passes, such as the mountain slopes facing the radar. Low radar backscatter signals refer to smooth surface (lakes) or radar grazing areas to radar shadow areas, seen in the southeast slopes. The area is approximately 29 kilometers by 21 kilometers (18 miles by 13.5 miles). The summit of the main peaks reaches elevations of 3,500 to 3,768 meters (xx feet to xx feet)above sea level. The test site's core area is the glacier region of Venter Valley, which is one of the most intensively studied areas for glacier research in the world. Research in Venter Valley (below center)includes studies of glacier dynamics, glacier-climate regions, snowpack conditions and glacier hydrology. About 25 percent of the core test site is covered by glaciers. Corner reflectors are set up for calibration. Five corner reflectors can be seen on the Gepatschferner and two can be seen on the Vernagtferner. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia |
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Budapest, Hungary, Perspecti
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PIA04952
Sol (our sun)
C-Band Interferometric Radar
| Title |
Budapest, Hungary, Perspective View, SRTM Elevation Model with Landsat Overlay |
| Original Caption Released with Image |
(Landsat), After draining the northern flank of the Alps Mountains in Germany and Austria, the Danube River flows east as it enters this west-looking scene (upper right) and forms the border between Slovakia and Hungary. The river then leaves the border as it enters Hungary and transects the Transdanubian Mountains, which trend southwest to northeast. Upon exiting the mountains, the river turns southward, flowing past Budapest (purplish blue area) and along the western margin of the Great Hungarian Plain. South and west of the Danube, the Transdanubian Mountains have at most only about 400 meters (about 1300 feet) of relief but they exhibit varied landforms, which include volcanic, tectonic, fluvial (river), and eolian (wind) features. A thick deposit of loess (dust deposits likely blown from ancient glacial outwash) covers much of this area, and winds from the northwest, funneled between the Alps and the Carpathian Mountains, are apparently responsible for a radial pattern of erosional streaks across the entire region. This image was generated from a Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM). The view uses a 3-times vertical exaggeration to enhance topographic expression. The false colors of the scene result from displaying Landsat bands 1, 4, and 7 in blue, green, and red, respectively. Band 1 is visible blue light, but bands 4 and 7 are reflected infrared light. This band combination maximizes color contrasts between the major land cover types, namely vegetation (green), bare ground (red), and water (blue). Shading of the elevation model was used to further highlight the topographic features. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. View Size: 133 kilometers (82 miles) wide, 90 kilometers (56 miles) distance Location: 47.5 degrees North latitude, 19.0 degrees East longitude Orientation: Looking West, 15 degrees down from horizontal, 3X vertical exaggeration Image Data: Landsat Bands 1, 4, 7 as blue, green, red respectively Date Acquired: February 2000 (SRTM), October 11, 1990 |
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