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Mysterious Blob Galaxies Rev …
Title Mysterious Blob Galaxies Revealed
Description This image composite shows a giant galactic blob (red, left) and the three merging galaxies NASA's Spitzer Space Telescope discovered within it (yellow, right). Blobs are intensely glowing clouds of hot hydrogen gas that envelop faraway galaxies. They are about 10 times as large as the galaxies they surround. Visible-light images like the one shown here (left), reveal the vast extent of blobs, but don't provide much information about their host galaxies. Using its heat-seeking infrared eyes, Spitzer was able to see the dusty galaxies tucked inside one well-known blob located 11 billion light-years away. The findings reveal three monstrously bright galaxies, trillions of times brighter than the Sun, in the process of merging together (right). Spitzer also observed three other blobs located in the same cosmic neighborhood, all of which were found to be glaringly bright. One of these blobs is also known to be a galactic merger, only between two galaxies instead of three. It remains to be seen whether the final two blobs studied also contain mergers. The Spitzer data were acquired by its multiband imaging photometer. The visible-light image was taken by the Blanco Telescope at the Cerro Tololo Inter-American Observatory, Chile.
Mysterious Blob Galaxies Rev …
Title Mysterious Blob Galaxies Revealed
Description This image composite shows a giant galactic blob (red, left) and the three merging galaxies NASA's Spitzer Space Telescope discovered within it (yellow, right). Blobs are intensely glowing clouds of hot hydrogen gas that envelop faraway galaxies. They are about 10 times as large as the galaxies they surround. Visible-light images like the one shown here (left), reveal the vast extent of blobs, but don't provide much information about their host galaxies. Using its heat-seeking infrared eyes, Spitzer was able to see the dusty galaxies tucked inside one well-known blob located 11 billion light-years away. The findings reveal three monstrously bright galaxies, trillions of times brighter than the Sun, in the process of merging together (right). Spitzer also observed three other blobs located in the same cosmic neighborhood, all of which were found to be glaringly bright. One of these blobs is also known to be a galactic merger, only between two galaxies instead of three. It remains to be seen whether the final two blobs studied also contain mergers. The Spitzer data were acquired by its multiband imaging photometer. The visible-light image was taken by the Blanco Telescope at the Cerro Tololo Inter-American Observatory, Chile.
Mysterious Blob Galaxies Rev …
Title Mysterious Blob Galaxies Revealed
Description This image composite shows a giant galactic blob (red, left) and the three merging galaxies NASA's Spitzer Space Telescope discovered within it (yellow, right). Blobs are intensely glowing clouds of hot hydrogen gas that envelop faraway galaxies. They are about 10 times as large as the galaxies they surround. Visible-light images like the one shown here (left), reveal the vast extent of blobs, but don't provide much information about their host galaxies. Using its heat-seeking infrared eyes, Spitzer was able to see the dusty galaxies tucked inside one well-known blob located 11 billion light-years away. The findings reveal three monstrously bright galaxies, trillions of times brighter than the Sun, in the process of merging together (right). Spitzer also observed three other blobs located in the same cosmic neighborhood, all of which were found to be glaringly bright. One of these blobs is also known to be a galactic merger, only between two galaxies instead of three. It remains to be seen whether the final two blobs studied also contain mergers. The Spitzer data were acquired by its multiband imaging photometer. The visible-light image was taken by the Blanco Telescope at the Cerro Tololo Inter-American Observatory, Chile.
Brief History of the Univers …
Title Brief History of the Universe
Description This artist's timeline chronicles the history of the universe, from its explosive beginning to its mature, present-day state. Our universe began in a tremendous explosion known as the Big Bang about 13.7 billion years ago (left side of strip). Observations by NASA's Cosmic Background Explorer and Wilkinson Anisotropy Microwave Probe revealed microwave light from this very early epoch, about 400,000 years after the Big Bang, providing strong evidence that our universe did blast into existence. Results from the Cosmic Background Explorer were honored with the 2006 Nobel Prize for Physics. A period of darkness ensued, until about a few hundred million years later, when the first objects flooded the universe with light. This first light is believed to have been captured in data from NASA's Spitzer Space Telescope. The light detected by Spitzer would have originated as visible and ultraviolet light, then stretched, or redshifted, to lower-energy infrared wavelengths during its long voyage to reach us across expanding space. The light detected by the Cosmic Background Explorer and the Wilkinson Anisotropy Microwave Probe from our very young universe traveled farther to reach us, and stretched to even lower-energy microwave wavelengths. Astronomers do not know if the very first objects were either stars or quasars. The first stars, called Population III stars (our star is a Population I star), were much bigger and brighter than any in our nearby universe, with masses about 1,000 times that of our sun. These stars first grouped together into mini-galaxies. By about a few billion years after the Big Bang, the mini-galaxies had merged to form mature galaxies, including spiral galaxies like our own Milky Way. The first quasars ultimately became the centers of powerful galaxies that are more common in the distant universe. NASA's Hubble Space Telescope has captured stunning pictures of earlier galaxies, as far back as ten billion light-years away.
Iapetus Thermal Radiation Im …
Description Iapetus Thermal Radiation Image
Full Description This image of the infrared heat radiation from Saturn's moon Iapetus was obtained by the Cassini composite infrared spectrometer instrument 16 hours before Cassini's closest approach to this mysterious moon, on December 31, 2004. The thermal radiation is shown as both a grayscale image, equivalent to what we would see if our eyes were sensitive to infrared wavelengths near 15 microns, and as a color-coded temperature map. A previously-released mosaic obtained by Cassini's imaging camera shortly before the composite infrared spectrometer observation, with similar scale and orientation, is also shown for comparison. Temperatures reach nearly 130 Kelvin (-226 Fahrenheit) at noon on the equator on the dark material that covers most of this side of Iapetus, making high noon on Iapetus's dark side probably the warmest places in the Saturn system. This is much warmer than temperatures on another Saturnian moon, Phoebe, measured by composite infrared spectrometer in June 2004. Those Phoebe temperature measurements peaked near 112 Kelvin (-258 Fahrenheit), because though Phoebe is almost as dark as Iapetus's dark material and absorbs nearly as much sunlight, Phoebe rotates much more quickly (once every 9 hours, compared to 79 days for Iapetus). That means the surface has less time to heat up during the day. Temperatures on Iapetus's bright material are much colder, peaking near 100 Kelvin (-280 Fahrenheit), both because the bright material absorbs less sunlight and because it is further from the equator on this side of Iapetus. Temperatures in the large crater near the center of the disc are slightly different from those in surrounding areas, because sloping surfaces within the crater are warmer where they are tilted towards the Sun and cooler when tilted away from the Sun. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the instrument team's home page, http://cirs.gsfc.nasa.gov/. *Credit*: NASA/JPL/GSFC
Date January 10, 2005
Iapetus Temperature Variatio …
Description Iapetus Temperature Variation Map
Full Description This plot shows how daytime temperatures at low latitudes on the dark material on Saturn's moon Iapetus vary with time of day, from about 130 Kelvin (-226 Fahrenheit) at noon to about 70 Kelvin (-334 Fahrenheit) at sunset. The observations are compared to a "forecast" model (green line) which predicts temperatures based on an assumed value of a parameter called the "thermal inertia. This measures how well the surface can retain heat as conditions change. Rock or solid ice has a high thermal inertia, roughly 2,000,000 as measured in the obscure units used for thermal inertia, meaning that it is good at storing heat and cools down or heats up relatively slowly. On Iapetus, in contrast, temperatures drop precipitously in the afternoon as the Sun sinks towards the horizon, and a very small value of the thermal inertia (30,000 units) is needed in the model to match the data. This means that Iapetus's surface is extremely bad at storing heat, and is thus extremely fluffy, probably due to the pulverizing effect of billions of years of meteorite impacts, though the mysterious process that has darkened this side of Iapetus may also have played a role. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the instrument team's home page, http://cirs.gsfc.nasa.gov/. *Credit*: NASA/JPL/GSFC
Date January 10, 2005
SOHO Watches Saturn and Cass …
Description SOHO Watches Saturn and Cassini Pass Behind the Sun
Full Description In this SOHO image taken July 21, 2005, the Sun is represented by the white circle in the center. Saturn is the bright object to the left of the Sun. Interestingly, the streak accompanying Saturn is not the rings but a distortion caused by Saturn's brightness. Saturn is approaching "superior conjunction," that is, it will be almost directly behind the Sun from Earth -- thus the Cassini spacecraft, in orbit around Saturn, will not be able to send or receive transmissions normally. Regular science data collection has been temporarily suspended. As Cassini passes closest by the limb (edge) of the Sun on July 24 PDT, communications will be impossible because of the Sun's radio noise. The spacecraft will regain full communication with Earth on July 27, once again returning Saturn science data. In the meantime, controllers are sending approximately 100 commands per day to test communication status. Cassini radio scientists are taking advantage of this opportunity to study the Sun's corona from its effects on the radio signals that reach Earth. SOHO (Solar and Heliospheric Observatory Satellite) orbits the Sun parked in one of the five gravitational-neutral spots, called Lagrange Points. This specific spot, called L1, stays in the same place relative to the Sun and the Earth, offering a continuously uninterrupted view of the Sun. Saturn is not in sight again until the evening of July 24. After that date, it will be to the RIGHT of the sun. For more information on "superior conjunction," visit: http://www.jpl.nasa.gov/basics/bsf1-2.html#conj . For more information on the Lagrange Points, visit: http://map.gsfc.nasa.gov/m_mm/ob_techorbit1.html For more information on SOHO, visit: http://sohowww.nascom.nasa.gov/ . Finally, the latest SOHO images are available at: http://sohowww.nascom.nasa.gov/data/realtime/c3/1024/latest.gif . Credit: SOHO -- http://sohowww.nascom.nasa.gov/
Date July 22, 2005
SOHO Watches Saturn and Cass …
Description SOHO Watches Saturn and Cassini Pass Behind the Sun
Full Description In this SOHO image taken July 21, 2005, the Sun is represented by the white circle in the center. Saturn is the bright object to the left of the Sun. Interestingly, the streak accompanying Saturn is not the rings but a distortion caused by Saturn's brightness. Saturn is approaching "superior conjunction," that is, it will be almost directly behind the Sun from Earth -- thus the Cassini spacecraft, in orbit around Saturn, will not be able to send or receive transmissions normally. Regular science data collection has been temporarily suspended. As Cassini passes closest by the limb (edge) of the Sun on July 24 PDT, communications will be impossible because of the Sun's radio noise. The spacecraft will regain full communication with Earth on July 27, once again returning Saturn science data. In the meantime, controllers are sending approximately 100 commands per day to test communication status. Cassini radio scientists are taking advantage of this opportunity to study the Sun's corona from its effects on the radio signals that reach Earth. SOHO (Solar and Heliospheric Observatory Satellite) orbits the Sun parked in one of the five gravitational-neutral spots, called Lagrange Points. This specific spot, called L1, stays in the same place relative to the Sun and the Earth, offering a continuously uninterrupted view of the Sun. Saturn is not in sight again until the evening of July 24. After that date, it will be to the RIGHT of the sun. For more information on "superior conjunction," visit: http://www.jpl.nasa.gov/basics/bsf1-2.html#conj . For more information on the Lagrange Points, visit: http://map.gsfc.nasa.gov/m_mm/ob_techorbit1.html For more information on SOHO, visit: http://sohowww.nascom.nasa.gov/ . Finally, the latest SOHO images are available at: http://sohowww.nascom.nasa.gov/data/realtime/c3/1024/latest.gif . Credit: SOHO -- http://sohowww.nascom.nasa.gov/
Date July 22, 2005
Enceladus Temperature Map
Description Enceladus Temperature Map
Full Description This image shows the surprise that startled Cassini scientists on the composite infrared spectrometer team when they got their first look at the infrared (heat) radiation from the south pole of Saturn's moon Enceladus. There is a dramatic warm spot centered on the pole that is probably a sign of internal heat leaking out of the icy moon. The data were taken during the spacecraft's third flyby of this intriguing moon on July 14, 2005. Based on data from previous flybys, which did not show the south pole well, team members expected that the south pole would be very cold, as shown in the left panel. Enceladus is one of the coldest places in the Saturn system because its extremely bright surface reflects 80 percent of the sunlight that hits it, so only 20 percent is available to heat the surface. As on Earth, the poles should be even colder than the equator because the sun shines at such an oblique angle there. The right hand panel shows a global temperature image made from measurements of Enceladus' heat radiation at wavelengths between 9 and 16.5 microns. Cassini made the observation from a distance of 84,000 kilometers (52,000 miles) on the approach to Enceladus, and the image shows details as small as 25 kilometers (16 miles). Equatorial temperatures are much as expected, topping out at about 80 degrees Kelvin (-315 degrees Fahrenheit), but the south pole is occupied by a well-defined warm region reaching 85 Kelvin (-305 degrees Fahrenheit). That is 15 degrees Kelvin (27 degrees Fahrenheit) warmer than expected. The composite infrared spectrometer data further suggest that small areas of the pole are at even higher temperatures, well over 110 degrees Kelvin (-261 degrees Fahrenheit). Evaporation of this relatively warm ice probably generates the cloud of water vapor detected above Enceladus' south pole by several other Cassini instruments. The south polar temperatures are very difficult to explain if sunlight is the only energy source heating the surface, though exotic sunlight-trapping mechanisms have not yet been completely ruled out. It therefore seems likely that portions of the polar region are warmed by heat escaping from the interior of the moon. This would make Enceladus only the third solid body in the solar system, after Earth and Jupiter's volcanic moon Io, where hot spots powered by internal heat have been detected. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The composite infrared spectrometer team homepage is, http://cirs.gsfc.nasa.gov/ . Credit: NASA/JPL/GSFC
Date July 29, 2005
Phoebe Temperature Maps
Description Phoebe Temperature Maps
Full Description A montage of maps of Saturn's moon Phoebe shows surface temperatures at various times of day as determined by the composite infrared spectrometer onboard Cassini during the June 11, 2004, Phoebe flyby. The asterisk on each map shows the location of the subsolar point, where the Sun is directly overhead. This point moves across the surface as Phoebe rotates. It is morning in regions to the left of the subsolar point, and afternoon in regions to the right. Like a newspaper weather map, different colors indicate different temperatures, though Phoebe's temperatures are distinctly cooler than even the coldest January day on Earth. Equatorial temperatures peak in the early afternoon near 112 Kelvin (-257 Fahrenheit), plunging to 78 Kelvin (-319 Fahrenheit) before dawn, and are even colder at higher latitudes. The large day/night temperature contrasts imply that Phoebe's surface is covered in loose dust or ice particles that store little heat and thus cool off rapidly at night. Regions of Phoebe's surface that were not observed are shown in black. Most of the maps show the effect on surface temperatures of the large crater-like depression seen in Cassini's visible-wavelength images of Phoebe, which is located just left of center in these maps. Crater walls that are shadowed and cold in the early morning in the first map are sunlit and warm in the late afternoon in the final map. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini composite infrared spectrometer home page at http://cirs.gsfc.nasa.gov/ . Image Credit: NASA/JPL/Goddard Space Flight Center
Slower Spinning Rings #1
Description Slower Spinning Rings #1
Full Description The Cassini composite infrared spectrometer obtained temperature maps of Saturn's main rings (A, B and C) that showed ring temperatures decreasing with increasing solar phase angle (the change of the sun-spacecraft-ring angle) on both the lit and unlit sides of the rings. Temperature changes throughout Saturn's main rings, as measured by the instrument, indicate that Saturn ring particles spin slowly compared to their orbital periods of 6 to 14 hours. They may spin several times per orbit to less than one time per orbit. Scans are shown for the lit and unlit rings, at relatively low (less than 60-degree) and high (more than 130-degree) phase angles. Each scan was painted on the rings at the correct ring orientation, creating a false color image. Warmer temperatures about minus 262 degrees Fahrenheit (110 Kelvin) are shown in red and cooler temperatures about minus 343 degrees (65 K) are shown in blue. Other colors indicate temperatures between minus 343 degrees and minus 262 degrees (65 K and 110 K). The scans of the lit rings are shown in the two panels on the left and scans of the unlit rings are shown in the two panels on the right. The thermal characteristics of each main ring vary noticeably with phase angle. Radial scans of the A, B and C rings show a decrease in temperature with increasing phase angle for both the lit and unlit sides of the rings. The C ring and Cassini Division exhibit the largest change in temperature. The temperature of the lit C ring decreases by about 22 degrees (12 Kelvin) between low and high phase angles. A similar contrast is present for the unlit side of the C ring. The C ring and Cassini Division are darker than the A and B rings so they can absorb more heat from the Sun. The lit B ring shows a temperature contrast of approximately 18 degrees (10 K) while the unlit B ring shows very little thermal contrast. Very little sunlight may make it through the thick B ring to its unlit side. The lit A ring is particularly interesting because the magnitude of the thermal contrast decreases with increasing radial distance from Saturn. The outer A ring shows only a small temperature change with phase angle, possibly because it contains smaller, or more rapidly rotating ring particles, which would have more uniform temperatures with phase angle. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the instrument team's home page, http://cirs.gsfc.nasa.gov/. Credit: NASA/JPL/GSFC
Date September 5, 2005
Slower Spinning Rings #2
Description Slower Spinning Rings #2
Full Description Temperature changes mapped with Cassini's composite and infrared spectrometer throughout Saturn's main rings show the ring temperatures decreasing with the increase of the Sun-spacecraft-ring angle (called phase angle) on both the lit and unlit sides of the rings. These temperature changes indicate that the ring particles spin slowly compared to their orbital periods of 6 to 14 hours. They may spin several times per orbit to less than one time per orbit. Four scans are shown for the lit and unlit rings, at relatively low (less than 60 degrees) and high (more than 130 degrees) phase angles. Warmer temperatures about minus 262 degrees Fahrenheit (110 Kelvin) are shown in red and cooler temperatures about minus 343 degrees (65 K) are shown in blue. Other colors indicate temperatures between minus 343 degrees and minus 262 degrees (65 K and 110 K). The top two scans are for the lit rings and the bottom two scans are for the unlit rings. The change in ring temperature between each scan can be seen clearly. The thermal characteristics of each main ring vary noticeably with phase angle. Radial scans of the A, B and C rings show a decrease in temperature with increasing phase angle for both the lit and unlit sides of the rings. The C ring and Cassini Division exhibit the largest change in temperature. The temperature of the lit C ring decreases by about 22 degrees (12 Kelvin) between low and high phase angles. A similar contrast is present for the unlit side of the C ring. The C ring and Cassini Division are darker than the A and B rings so they can absorb more heat from the Sun. The lit B ring shows a temperature contrast of approximately 18 degrees (10 K) while the unlit B ring shows very little thermal contrast. Very little sunlight may make it through the thick B ring to its unlit side. The lit A ring is particularly interesting because the magnitude of the thermal contrast decreases with increasing radial distance from Saturn. The outer A ring shows only a small temperature change with phase angle, possibly because it contains smaller, or more rapidly rotating ring particles, which would have more uniform temperatures with phase angle. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the instrument team's home page, http://cirs.gsfc.nasa.gov/.
Date September 5, 2005
Iapetus Temperature Map
Description Iapetus Temperature Map
Full Description This temperature map of Saturn's moon Iapetus is constructed from observations of Iapetus's infrared heat radiation taken with the Cassini composite infrared spectrometer instrument during the Dec. 31, 2004 flyby. The orange asterisk marks the point on Iapetus where the Sun is directly overhead. Temperatures reach nearly 130 Kelvin (-226 Fahrenheit) at noon on the equator on the dark material that covers most of this side of Iapetus, making high noon on Iapetus's dark side probably the warmest places in the Saturn system. This is much warmer than temperatures on the moon Phoebe measured by the composite infrared spectrometer in June 2004, which peaked near 112 Kelvin (-258 Fahrenheit). That's because, although Phoebe is almost as dark as Iapetus's dark material and absorbs nearly as much sunlight, Phoebe rotates much more quickly (once every 9 hours, compared to 79 days for Iapetus). That means the surface has less time to heat up during the day. Temperatures on Iapetus' bright material are much colder, peaking near 100 Kelvin (-280 Fahrenheit), both because the bright material absorbs less sunlight and because it is further from the equator on this side of Iapetus. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the instrument team's home page, http://cirs.gsfc.nasa.gov/. *Credit*: NASA/JPL/GSFC
Date January 10, 2005
Hot Shot
title Hot Shot
description The black dot in this picture of the Sun is Mercury. The planet made a rare pass in front of the Sun on May 7, 2003. The SOHO and TRACE spacecraft were watching with all instruments. The spacecraft websites are among many with Mercury transit galleries. *Image Credit*: NASA Goddard Space Flight Center
Hubble Follows Rapid Changes …
Title Hubble Follows Rapid Changes in Jupiter's Aurora
Spitzer and Hubble Capture E …
Title Spitzer and Hubble Capture Evolving Planetary Systems
Spitzer and Hubble Capture E …
Title Spitzer and Hubble Capture Evolving Planetary Systems
Spitzer and Hubble Capture E …
Title Spitzer and Hubble Capture Evolving Planetary Systems
Spitzer and Hubble Capture E …
Title Spitzer and Hubble Capture Evolving Planetary Systems
Spitzer and Hubble Capture E …
Title Spitzer and Hubble Capture Evolving Planetary Systems
A Summer View of Russia's Le …
Title A Summer View of Russia's Lena Delta and Olenek River
Description These views of the Russian Arctic were acquired by NASA's Multi-angle Imaging SpectroRadiometer (MISR) instrument on July 11, 2004. The brief arctic summer had transformed the frozen tundra and the thousands of lakes, channels, and rivers of the Lena Delta into a fertile wetland, and the usual blanket of thick snow had melted from the vast plains and taiga forests. The images show an area in the northern part of the Sakha Republic in eastern Siberia. The Olenek River wends northeast from the bottom of the images to the upper left, and the delta through which the mighty Lena River empties into the Laptev Sea dominate the top portions of the images. Creating accurate maps of vegetation structure is essential for understanding the seasonal exchanges of energy and water at the Earth's surface and for preserving biodiversity. The left-hand image is a natural-color image from MISR's nadir (vertical-viewing) camera, in which the rivers appear murky due to sediment, and photosynthetically active vegetation appears green. The center image is also from MISR's nadir camera, but is a false-color view in which the predominant red color is due to the brightness of vegetation at near-infrared wavelengths. Apart from the Lena Delta, the most photosynthetically active regions are within the lower half of the image and throughout the great stretch of land that curves across the Olenek River.  The relatively barren ranges of the Volyoi Mountains appear as the pale tan-colored area to the right of image center. The right-hand image is a multiangle, false-color view made from the red band data of the 60-degree-backward, nadir, and 60-degree-forward cameras, displayed as red, green and blue, respectively. Water appears blue in this image because sun glint makes smooth, wet surfaces look brighter at the forward camera's view angle. Much of the landscape and many low clouds appear purple because these surfaces are both forward and backward scattering, and clouds that are further from the surface appear in a different spot for each view angle, creating a rainbow-like appearance. The highly vegetated region in the natural-color nadir image exhibits a faint greenish hue in the multi-angle composite. This subtle effect suggests that the nadir camera is observing more of the brighter, underlying surface than the oblique cameras, providing information about the distribution and density of trees and shrubs in this area. The Multiangle Imaging SpectroRadiometer observes the daylit Earth continuously, and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. The MISR Browse Image Viewer [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://eosweb.larc.nasa.gov/MISRBR/ ], provides access to low-resolution true-color versions of these images. These data products were generated from a portion of the imagery acquired during Terra orbit 24273. The panels cover an area of about 230 kilometers x 420 kilometers, and utilize data from blocks 30 to 34 within World Reference System-2 path 134. 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 of Technology. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. [ http://www-misr.jpl.nasa.gov/ ] Text by Clare Averill (Raytheon/JPL).
Global, Seasonal Surface Alb …
Title Global, Seasonal Surface Albedos
Description Global models of the Earth system need accurate measurements of how much solar energy is reflected and absorbed by surfaces because this energy drives processes such as plant photosynthesis, snow melt, and longwave reradiation. These images from the Multi-angle Imaging SpectroRadiometer (MISR) provide global, seasonal summaries of a quantity called the Directional Hemispherical Reflectance (DHR), also sometimes referred to as the "black-sky" albedo. The amount of sunlight reflected from a surface, relative to the incident amount, is called the albedo. Bright surfaces have albedo near unity, and dark surfaces have albedo near zero. The DHR refers to the amount of spectral radiation reflected into all upward directions through an imaginary hemisphere situated above each surface point. The "directional" part of the name describes how, in the absence of an intervening atmosphere, light from the Sun would illuminate the surface from a single direction (that is, there is no diffuse skylight, hence the name "black-sky" albedo). To generate this product accurately, it is necessary to compensate for the effects of the atmosphere, and MISR's multi-angle retrieval techniques are used to screen clouds and account for the light scattered by airborne particulates (aerosols). The four image panels show DHR as it was retrieved over land surfaces in MISR's red, green, blue spectral bands (left), and near-infrared, red, blue spectral bands (right), for the seasonal periods December 2001 through February 2002 (top), and June 2002 through August 2002 (bottom). A one-year movie is also provided. Since relatively little sunlight reaches the polar regions during winter, the images were cropped to include only the area which is illuminated in both hemispheres during winter and summer. Noteworthy features include seasonal vegetation and the advance and retreat of the snow line. Regions where DHR could not be derived, either due to an inability to retrieve the necessary atmospheric characteristics or due to the presence of clouds, are shown in black. Further global summaries of the DHR (and other surface and vegetation products) from MISR are now available at the NASA Langley Atmospheric Sciences Data Center. [ http://eosweb.larc.nasa.gov/ ] The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://www-misr.jpl.nasa.gov/ ] Text by Clare Averill (Acro Service Corporation/JPL) and David J. Diner (JPL).
Dewatering Effects from the …
Title Dewatering Effects from the Gujarat Earthquake
Description MISR Browse Image Viewer [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://eosweb.larc.nasa.gov/MISRBR/ ] provides access to low-resolution true-color versions of these images. This data product was generated from a portion of the imagery acquired during Terra orbits 5736 and 5969. The full-size images cover an area of 215 kilometers x 156 kilometers, and utilize data from blocks 71 to 72 within World Reference System-2 path 151. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://www-misr.jpl.nasa.gov/ ] Text by Clare Averill (Acro Service Corporation/JPL) and David J. Diner (JPL)., browse image of orbit 5969 (380 KB JPEG) On January 26, 2001, when India's Republic Day is normally celebrated, a devastating earthquake hit the state of Gujarat. About 20,000 people died and millions were injured throughout the region. The earthquake had a magnitude of 7.7 on the Richter scale. After the earthquake, local residents reported a mixture of water and sediments fountaining from the Earth. These effects, referred to as dewatering, can result from intense ground shaking by strong earthquakes in regions with shallow water tables. Scientists initially observed dewatering in parts of the Rann of Kutch (a large salt pan in northern Gujarat), and in areas close to the earthquake epicenter. Recent research utilizes the unique capabilities of the Multi-angle Imaging SpectroRadiometer (MISR) instrument to observe earthquake-related dewatering over a broader area (related story: NASA Satellite Helps Scientists See Effects of Earthquakes in Remote Areas [ http://earthobservatory.nasa.gov/Newsroom/NasaNews/2003/2003020511146.html ]). This research is published in the February 4, 2003, issue of EOS Transactions of the American Geophysical Union. These two false-color MISR images were acquired before and after the event, on January 15 and 31, respectively. The earthquake epicenter was located about 80 kilometers east of the city of Bhuj, situated in the lower part of the images. The later image depicts numerous areas where groundwater flowed up to the surface, including within the Rann of Kutch, as well as near the Indo-Pakistani border. These regions of earthquake-associated surface water are apparent up to 200 kilometers from the earthquake's epicenter. Water was observed in many remote areas, especially near the Indo-Pakistani border, which were not easily accessible to survey teams on the ground. Changes in reflection at different view angles and in the near-infrared spectral region assist with the identification of surface water, which appears here in shades of blue and purple. In these visualizations, data from the red band of MISR's most obliquely backward and forward-viewing cameras are displayed as red and blue, respectively, and data from the near-infrared band of MISR's vertically-downward viewing (nadir) camera are displayed as green. Water bodies tend to be more absorbing in the near-infrared, and to be brighter in the view acquired by the more sun-facing (in this case, the 70-degree forward) camera. This combination enhances the ability to distinguish wet surfaces. True color and multi-angle visualizations [ http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=4810 ] of these data were also released in April 2001. 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. The
Dewatering Effects from the …
Title Dewatering Effects from the Gujarat Earthquake
Description MISR Browse Image Viewer [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://eosweb.larc.nasa.gov/MISRBR/ ] provides access to low-resolution true-color versions of these images. This data product was generated from a portion of the imagery acquired during Terra orbits 5736 and 5969. The full-size images cover an area of 215 kilometers x 156 kilometers, and utilize data from blocks 71 to 72 within World Reference System-2 path 151. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://www-misr.jpl.nasa.gov/ ] Text by Clare Averill (Acro Service Corporation/JPL) and David J. Diner (JPL)., browse image of orbit 5969 (380 KB JPEG) On January 26, 2001, when India's Republic Day is normally celebrated, a devastating earthquake hit the state of Gujarat. About 20,000 people died and millions were injured throughout the region. The earthquake had a magnitude of 7.7 on the Richter scale. After the earthquake, local residents reported a mixture of water and sediments fountaining from the Earth. These effects, referred to as dewatering, can result from intense ground shaking by strong earthquakes in regions with shallow water tables. Scientists initially observed dewatering in parts of the Rann of Kutch (a large salt pan in northern Gujarat), and in areas close to the earthquake epicenter. Recent research utilizes the unique capabilities of the Multi-angle Imaging SpectroRadiometer (MISR) instrument to observe earthquake-related dewatering over a broader area (related story: NASA Satellite Helps Scientists See Effects of Earthquakes in Remote Areas [ http://earthobservatory.nasa.gov/Newsroom/NasaNews/2003/2003020511146.html ]). This research is published in the February 4, 2003, issue of EOS Transactions of the American Geophysical Union. These two false-color MISR images were acquired before and after the event, on January 15 and 31, respectively. The earthquake epicenter was located about 80 kilometers east of the city of Bhuj, situated in the lower part of the images. The later image depicts numerous areas where groundwater flowed up to the surface, including within the Rann of Kutch, as well as near the Indo-Pakistani border. These regions of earthquake-associated surface water are apparent up to 200 kilometers from the earthquake's epicenter. Water was observed in many remote areas, especially near the Indo-Pakistani border, which were not easily accessible to survey teams on the ground. Changes in reflection at different view angles and in the near-infrared spectral region assist with the identification of surface water, which appears here in shades of blue and purple. In these visualizations, data from the red band of MISR's most obliquely backward and forward-viewing cameras are displayed as red and blue, respectively, and data from the near-infrared band of MISR's vertically-downward viewing (nadir) camera are displayed as green. Water bodies tend to be more absorbing in the near-infrared, and to be brighter in the view acquired by the more sun-facing (in this case, the 70-degree forward) camera. This combination enhances the ability to distinguish wet surfaces. True color and multi-angle visualizations [ http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=4810 ] of these data were also released in April 2001. 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. The
Eruption of Klyuchevskaya Vo …
Title Eruption of Klyuchevskaya Volcano
Description The rising sun bathes the eastern half of Russia's Kamchatka Peninsula with light, casting long shadows in the west. The shadows highlight the plume of ash that continues to rise from the Klyuchevskaya Volcano. The largest and most active volcano on the peninsula, Klyuchevskaya has erupted regularly since its first recorded eruption in 1697. Its most recent activity began in mid-January 2005, and has not abated. Dark ash from the ongoing eruption dusts the snow in this image, acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER [ http://asterweb.jpl.nasa.gov/ ]) on NASA's Terra [ http://terra.nasa.gov/ ] satellite on March 12, 2005. In addition to the large plume of ash visible in this image, the ongoing eruption has sent molten lava down the volcano's northeast slope, where it is melting the Ehrman glacier. This activity may be responsible for the rivers of water that can be seen in the snow near the northeast base of the volcano. NASA image created by Jesse Allen, Earth Observatory, using data provided courtesy of NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.
Liquefaction Effects from th …
Title Liquefaction Effects from the Bhuj Earthquake
Description These Multi-angle Imaging Spectroradiometer (MISR) images show the Kachchh region in the Gujarat province of western India. On January 26, 2001, a magnitude 7.7 earthquake devastated this area, killing 20,000 people and destroying buildings, dams, and port facilities. The two upper MISR images are pre- and post-earthquake scenes acquired on January 15 and January 31, 2001, respectively. They are "true-color" images made by combining the red, green and blue bands from the nadir (vertically down-looking) camera. The two lower views are "false-color" images made by combining the red bands from three different cameras. Blue is assigned to the camera pointing 70 degrees forward (more sun-facing), green to the nadir camera, and red to the camera pointing 70 degrees aftward. Each of these images is about 275 kilometers wide by 218 kilometers high. The earthquake epicenter was just below the southern tip of the large, white area on the right-hand side of the images, and about 70 kilometers northeast of the city of Bhuj. The earthquake may have occurred on the Kachchh Mainland Fault, which extends from the region of the epicenter westward along the curved boundary between the darker brown region to the south and the lighter brown area north of it. The compressive stresses responsible for the earthquake are related to the collision of India with Asia and the resulting rise of the Himalayas to the northeast. That part of the Kachchh region which lies north of the Kachchh Mainland Fault includes the Banni Plains and the Rann of Kachchh. It is a low, flat basin characterized by salt pans and mud flats. The salt forms in the Rann of Kachchh as mineral-laden waters evaporate. The salt flats can be seen in the nadir images as highly reflective, white and gray areas. During the earthquake, strong shaking produced liquefaction in the fine silts and sands below the water table in the Rann of Kachchh. This caused the mineral grains to settle and expel their interstitial water to the surface. Field investigations have found abundant evidence of mud volcanos, sand boils, and fissures from which salty ground water erupted over an area exceeding 10,000 square kilometers. Evidence of the expelled water can also be seen on the MISR images. Notice the delicate, dendritic pattern of stream channels throughout many of the salt-flats on the post-earthquake image, especially due north of the epicenter. These carried water brought to the surface by liquefaction during the earthquake. Areas where shallow surface water is present are much easier to see on the false-color multi-angle composite images. Wet areas are exhibiting a combination of enhanced forward-scattered light due to the reflection by the water, and enhanced backward scattering due to surface roughness or the presence of sediments. This combination results in blue to purple hues. The region of sand dunes in the upper right and the Indus River valley and delta in the upper left are inside Pakistan. Near the top, of the images, there is an east-west trending linear feature separating the Thar desert of Pakistan from the Rann of Kachchh. This is the Nagar Parkar Fault. On both pre-earthquake images, this feature is evident only from the contrasting brown colors on either side of it. On the post-earthquake images, a narrow ribbon defines the boundary between the two geologic provinces. However, only in the multi-angle composite do we see evidence that this ribbon may be a water-filled channel. Because this area is politically sensitive and fairly inaccessible, no field teams have been able to verify liquefaction effects or the presence of water there. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://www-misr.jpl.nasa.gov/ ]
Los Angeles Faults
Title Los Angeles Faults
Description Los Angeles, Calif., is one of the world's largest metropolitan areas with a population of about 15 million people. The urban areas mostly cover the coastal plains and lie within the inland valleys. The intervening and adjacent mountains are generally too rugged for much urban development. This is in large part because the mountains are "young," meaning they are still building (and eroding) in this seismically active (earthquake prone) region. Earthquake faults commonly lie between the mountains and the lowlands. The San Andreas fault, the largest fault in California, likewise divides the very rugged San Gabriel Mountains from the low-relief Mojave Desert, thus forming a straight topographic boundary between the top center and lower right corner of the image. We present this perspective image from NASA's Shuttle Radar Topography Mission (SRTM) with a graphic overlay that maps faults that have been active in Late Quaternary times (white lines). The fault database was provided by the U.S. Geological Survey. The Landsat image used here was acquired on May 4, 2001, about seven weeks before the summer solstice, so natural terrain shading is not particularly strong. It is also not especially apparent given a view direction (northwest) nearly parallel to the sun illumination (shadows generally fall on the backsides of mountains). Consequently, topographic shading derived from the SRTM elevation model was added to the Landsat image, with a false sun illumination from the left (southwest). This synthetic shading enhances the appearance of the topography. Size: View width 134 kilometers (83 miles), view distance 150 kilometers (93 miles) Location: 34.3 degrees North latitude, 118.4 degrees West longitude Orientation: View west-northwest, 1.8 X vertical exaggeration Image Data: Landsat Bands 3, 2+4, 1 as red, green, blue, respectively Original Data Resolution: SRTM 1 arcsecond (30 meters or 98 feet), Landsat 30 meters (98 feet) Graphic Data: Earthquake faults active in Late Quaternary times Date Acquired: February 2000 (SRTM), May 4, 2001 (Landsat). Image Courtesy SRTM Team [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://www.jpl.nasa.gov/srtm/ ] NASA/JPL/NIMA and Landsat 7 Science Team [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://landsat7.usgs.gov/ ] NASA GSFC/USGS
Mount St. Helens
Title Mount St. Helens
Description Hot lava had broken through the surface of the growing lava dome on Mount St. Helens when the MASTER sensor took this image in the early morning hours of October 13, 2004. MASTER, which stands for MODIS/ASTER Airborne Simulator, is an aircraft- mounted remote sensing device built to simulate the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov/ ]) and Advanced Spaceborne Thermal Emission and Reflection Radiometer [ http://asterweb.jpl.nasa.gov/ ] (ASTER) instruments on NASA's Terra [ http://terra.nasa.gov/ ] satellite. The top image was made from MASTER's thermal sensitive bands, and shows the heat in the volcano's crater. A brilliant white spot on the southwest side of the crater is hot lava bubbling to the surface. Smaller, less intense hot spots around the crater have formed where magma near the surface has heated the rock above it. The dark area around the lava dome is the crater. Shielded from the sun and covered with snow, the dark crater floor is cooler than the surrounding landscape, which appears red. A plume of steam rising from the lava dome (colored purple) drifts southeast in this image. The plume and crater floor are more visible in the lower, true color image. Acquired just after dawn, the image has few shadows and low contrast. An image composed of thermal infrared and visible light wavelengths reveals more details around the mountain. The volcanic plume is bright cyan, the cool crater is purple, and snow is light blue. To the north of the volcano, two bright red lines extend from south to north. These are warm-water streams, possibly heated by the active volcano. NASA images courtesy Jeff Myers, MASTER [ http://masterweb.jpl.nasa.gov/ ] instrument team, NASA Ames Research Center
Mount St. Helens
Title Mount St. Helens
Description Hot lava had broken through the surface of the growing lava dome on Mount St. Helens when the MASTER sensor took this image in the early morning hours of October 13, 2004. MASTER, which stands for MODIS/ASTER Airborne Simulator, is an aircraft- mounted remote sensing device built to simulate the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov/ ]) and Advanced Spaceborne Thermal Emission and Reflection Radiometer [ http://asterweb.jpl.nasa.gov/ ] (ASTER) instruments on NASA's Terra [ http://terra.nasa.gov/ ] satellite. The top image was made from MASTER's thermal sensitive bands, and shows the heat in the volcano's crater. A brilliant white spot on the southwest side of the crater is hot lava bubbling to the surface. Smaller, less intense hot spots around the crater have formed where magma near the surface has heated the rock above it. The dark area around the lava dome is the crater. Shielded from the sun and covered with snow, the dark crater floor is cooler than the surrounding landscape, which appears red. A plume of steam rising from the lava dome (colored purple) drifts southeast in this image. The plume and crater floor are more visible in the lower, true color image. Acquired just after dawn, the image has few shadows and low contrast. An image composed of thermal infrared and visible light wavelengths reveals more details around the mountain. The volcanic plume is bright cyan, the cool crater is purple, and snow is light blue. To the north of the volcano, two bright red lines extend from south to north. These are warm-water streams, possibly heated by the active volcano. NASA images courtesy Jeff Myers, MASTER [ http://masterweb.jpl.nasa.gov/ ] instrument team, NASA Ames Research Center
Rice Cultivation in Northwes …
Title Rice Cultivation in Northwest Italy
Description The lowlands of Lombardy and Piedmont in northwest Italy are some of the most highly developed irrigation areas in the world. Irrigated lands cover at least 160,000 acres in this part of Italy, where rice is the most important crop. These views of the region were acquired on May 8, 2005, by NASA's Multi-angle Imaging SpectroRadiometer (MISR). The multiple viewing angles provided by MISR's nine cameras make it possible to tell wet surfaces, including flooded lands, from other surfaces, and they also make cities easy to locate. The left-hand image is a natural-color view acquired by MISR's downward-looking (nadir) camera, and the right-hand image is a combination of red band data from MISR's 60-degree-backward-, nadir, and 60-degree-forward-viewing cameras. (Red band is what scientists call the "channel" on the sensor that detects red light.) Color changes indicate surface texture, which is influenced by terrain, vegetation structure, soil type, and surface wetness. Wet surfaces or areas with standing water appear in blue or purple-blue hues. The purple-blue areas that dominate the center-left part of the image are part of the extensive irrigation network that exists throughout the plains and meadows of the region. Cities with tall buildings appear in red-orange hues. In this type of image, the city of Milan is the most obvious. The small orange area in the center of the purple inundated area indicates the location of Vercelli, and the larger city of Milan is the orange area to the northeast, on the other side of the Ticino River. To a lesser extent, the cities of Novara, Pavia, Galliate, Mortara, and Vigevano are also identifiable by their orange hues. MISR can tell various surface features like cities or irrigated areas apart because of the way surfaces reflect light. A smooth water surface tends to reflect sunlight away from the Sun. This effect is most apparent when a satellite views the surface with the Sun in front of the camera. Similarly, rough surfaces tend to reflect light back towards the Sun, and this "backward scattering" is most obvious when a satellites views a surface with the Sun behind the camera. Clouds present over the high country to the west of the Lago Maggiore (upper left corner) and along the coast of the Golfo di Genova (bottom) appear in a different spot for each view angle, creating a rainbow-like appearance. Mountains also have a "wavy" look in the multi-angle combination because, like clouds, their height above the surface makes them appear in a different spot in each camera's view angle. The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the entire globe between 82 degrees North and 82 degrees South latitude every nine days. This image covers an area of about 131 kilometers by 191 kilometers. These data products were generated from a portion of the imagery acquired during Terra orbit 28660 and utilize data from block 54 within World Reference System-2 path 193. MISR was, built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is managed for NASA by the California Institute of Technology. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. [ http://www-misr.jpl.nasa.gov/ ] Text by Clare Averill (Raytheon ITSS/JPL)
Eros Encounter Nears
Title Eros Encounter Nears
Explanation After an unanticipated [ http://antwrp.gsfc.nasa.gov/apod/ap000205.html ] extra trip around the Sun, the NEAR spacecraft [ http://near.jhuapl.edu/ ] is now politely approaching [ http://near.jhuapl.edu/iod/000/index.html ] asteroid 433 [ http://near.jhuapl.edu/eros/history/too_many.html ], Eros [ http://near.jhuapl.edu/eros/history/ ], at a respectful relative speed of about 20 miles per hour. Still nearly 2,000 miles distant, NEAR will [ http://www.jhuapl.edu/public/pr/000208.htm ] close to within approximately 200 miles by February 14th - Valentine's Day. If all goes well, the spacecraft will then be captured by the gentle attraction of Eros' [ http://near.jhuapl.edu/eros/sum.html ] gravity, becoming the first artificial moon of an asteroid [ http://antwrp.gsfc.nasa.gov/apod/ap990807.html ]. While Eros is not round [ http://nearweb.jhuapl.edu/cgi-bin/ion-p?page=near_shape.html ] it is certainly not heart-shaped [ http://echo.jpl.nasa.gov/asteroids/433_Eros/eros.html ] either as seen in this series [ http://near.jhuapl.edu/iod/20000207/index.html ] of frames showing the roughly 20 x 8 x 8 mile asteroid during its 5.27 hour rotation period. Different [ http://www.seds.org/nineplanets/nineplanets/pxmisc.html#otherast ] perspectives clearly show a gouge or saddle and a large impact crater with a raised rim near the asteroid's [ http://www.boulder.swri.edu/~cchapman/finderos.html ] narrow waist. The frames were recorded by the NEAR spacecraft's multi-spectral imager [ http://near.jhuapl.edu/instruments/ ] on February 4th from a range of 4,600 miles.
McCool Hill on Mars
Title McCool Hill on Mars
Explanation You can make it. Winter is rapidly advancing on the southern hemisphere on Mars [ http://www.planetary.org/explore/topics/mars/ ], and the lack of sunlight could be dangerous unless you find a good place to hibernate [ http://www.pbs.org/wgbh/nova/satoyama/hibernation.html ]. There it is ahead: McCool Hill. As the robotic Spirit rover [ http://science.howstuffworks.com/mars-rover3.htm ] rolling across Mars, you are told that this will be a good place to spend the Martian winter [ http://antwrp.gsfc.nasa.gov/apod/ap030602.html ]. On the north slope of McCool [ http://www.jsc.nasa.gov/Bios/htmlbios/mccool.html ] Hill, you can tilt your solar panels [ http://en.wikipedia.org/wiki/Solar_panels ] toward the Sun enough to generate the power you need to keep running through the winter. Between you and McCool Hill [ http://www.planetary.org/news/2006/0228_Mars_Exploration_Rovers_Update_Spirit.html ] is an unusual reddish outcropping of rocks. Also visible above [ http://photojournal.jpl.nasa.gov/catalog/PIA02688 ], unusual layered rocks [ http://antwrp.gsfc.nasa.gov/apod/ap001205.html ] lie to your right, while other scattered rocks appear either smooth [ http://antwrp.gsfc.nasa.gov/apod/ap060126.html ] or sponge [ http://en.wikipedia.org/wiki/Spongebob ]-like. Fortunately, there is still some time to explore, and the landscape before you may hold more clues to the history of ancient Mars [ http://antwrp.gsfc.nasa.gov/apod/ap040303.html ].
Natural Saturn On The Cassin …
Title Natural Saturn On The Cassini Cruise
Explanation What could you see approaching Saturn [ http://www.jpl.nasa.gov/cassini/Kids/stories/ ] aboard an interplanetary cruise [ http://www.jpl.nasa.gov:80/cassini/Mission/cruise.html ] ship? Your view would likely resemble this subtly shaded image [ http://oposite.stsci.edu/pubinfo/pr/1998/28/b.html ] of the gorgeous ringed gas giant. Processed by the Hubble Heritage project [ http://heritage.stsci.edu/ ], the picture intentionally avoids overemphasizing color contrasts and presents a natural looking Saturn [ http://heritage.stsci.edu/ public/Oct22/saturn/saturntable.html#caption ] with cloud bands, storms [ http://antwrp.gsfc.nasa.gov/apod/ap951018.html ], nearly edge-on rings [ http://antwrp.gsfc.nasa.gov/apod/ap981018.html ], and the small round shadow of the moon Enceladus near the center of the planet's disk. Of course, seats were not available on the only ship currently enroute [ http://www.jpl.nasa.gov/cassini/ ] - the Cassini spacecraft, launched in 1997 [ http://antwrp.gsfc.nasa.gov/apod/ap971016.html ] and scheduled to arrive at Saturn [ http://www.jpl.nasa.gov/cassini/today/ ] in the year 2004. After an extended cruise to a world 1,400 million kilometers from the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap960727.html ], Cassini will tour the Saturnian system [ http://www.hawastsoc.org/solar/eng/saturn.htm ], conducting a remote, robotic exploration with software and instruments designed by [ http://www.jpl.nasa.gov/cassini/Partners/ ] denizens of planet Earth. But where is Cassini now [ http://www.jpl.nasa.gov/cassini/today/ ]? Still about 980 million kilometers from Saturn, last Sunday the spacecraft flew by asteroid 2685 Masursky [ http://www.jpl.nasa.gov/cassini/MoreInfo/ sigevents/sigevent000128.html ].
Southwest Mercury
Title Southwest Mercury
Explanation The planet Mercury resembles a moon. Mercury [ http://www.seds.org/nineplanets/nineplanets/mercury.html ]'s old surface is heavily cratered [ http://liftoff.msfc.nasa.gov/Academy/SPACE/SolarSystem/Meteors/Craters.html ] like many moons. Mercury [ http://www.solarviews.com/eng/mercury.htm ] is larger than most moons but smaller than Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap990806.html ]'s moon Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap990304.html ] and Saturn [ http://antwrp.gsfc.nasa.gov/apod/ap960717.html ]'s moon Titan [ http://antwrp.gsfc.nasa.gov/apod/ap990207.html ]. Mercury is much denser and more massive than any moon, though, because it is made mostly of iron. In fact, the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990131.html ] is the only planet more dense. A visitor to Mercury's surface [ http://antwrp.gsfc.nasa.gov/apod/ap960121.html ] would see some strange sights. Because Mercury [ http://www.oulu.fi/~spaceweb/textbook/mercury.html ] rotates exactly three times every two orbits around the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap951004.html ], and because Mercury [ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mercury.html ]'s orbit is so elliptical, a visitor to Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap990102.html ] might see the Sun [ http://antwrp.gsfc.nasa.gov/htmltest/gifcity/interv.html ] rise, stop in the sky, go back toward the rising horizon [ http://antwrp.gsfc.nasa.gov/apod/ap990619.html ], stop again, and then set quickly over the other horizon. From Earth [ http://antwrp.gsfc.nasa.gov/apod/ap980530.html ], Mercury's proximity to the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ] cause it to be visible only for a short time just after sunset or just before sunrise.
Animation of Asteroids Passi …
Title Animation of Asteroids Passing Near Earth
Explanation How often does an asteroid whiz by the Earth? The above time-lapse animation [ http://cfa-www.harvard.edu/iau/Animations/Animations.html ] follows the orbit of the Earth around the Sun for two months in 2002 as numerous asteroids [ http://en.wikipedia.org/wiki/Asteroids ], also known as minor planets [ http://en.wikipedia.org/wiki/Minor_planet ], approach and pass by. Some asteroids appear out of nowhere [ http://antwrp.gsfc.nasa.gov/apod/ap041001.html ] as they are plotted only when they were discovered. Most asteroids plotted were discovered only [ http://antwrp.gsfc.nasa.gov/apod/ap040322.html ] during the previous year. Although none of the plotted objects came inside the orbit of our Moon, our Solar System is filled with objects [ http://antwrp.gsfc.nasa.gov/apod/ap050417.html ] as small as bits of sand, usually left by a comet, that appear as meteors as they streak into the Earth's atmosphere every day. The only objects displayed are those visible from Earth [ http://antwrp.gsfc.nasa.gov/apod/ap050102.html ] closer than 20 million kilometers, color coded by three-dimensional distance. In comparison, the Earth is a relatively small target having a radius of about 6,400 kilometers. One significant research area [ http://pan-starrs.ifa.hawaii.edu/public/asteroid-threat/asteroid_threat.html ] in modern astronomy involves trying to find the majority of asteroids that could pose a future collision threat [ http://neo.jpl.nasa.gov/risk/ ] with Earth.
Stereo Eros
Title Stereo Eros
Explanation Get out your red/blue glasses [ http://mpfwww.jpl.nasa.gov/MPF/mpf/glasses.html ] and float next to asteroid 433 Eros [ http://www.boulder.swri.edu/~cchapman/finderos.html ], 260 million kilometers away! Orbiting the Sun once every 1.8 earth-years, asteroid Eros [ http://near.jhuapl.edu/eros/history/eros_useful.html ] is a diminutive 40 x 14 x 14 kilometer world of undulating horizons, craters, boulders [ http://antwrp.gsfc.nasa.gov/apod/ap000216.html ] and valleys. Its unsettling scale and bizarre shape are emphasized in this picture [ http://near.jhuapl.edu/NEAR/iod/20000218/index.html ] - a mosaic of recent images from the NEAR spacecraft processed [ http://visearth.ucsd.edu/Stereo/ ] to yield a stereo anaglyphic [ http://near.jhuapl.edu/NEAR/3_d.html ] view. Along with dramatic chiaroscuro, NEAR's 3-D imaging provides important measurements of the asteroid's landforms and structures, and hopefully clues to the origin [ http://near.jhuapl.edu/NEAR/Voyage/1.html ] of this city-sized chunk of solar system [ http://space.jpl.nasa.gov/ ]. The smallest features visible here are about 30 meters across.
Saturn At Night
Title Saturn At Night
Explanation From a spectacular [ http://antwrp.gsfc.nasa.gov/apod/ap970829.html ] vantage point over 1.4 billion [ http://antwrp.gsfc.nasa.gov/apod/ap980620.html ] kilometers from the sun, the Voyager [ http://nssdc.gsfc.nasa.gov/planetary/voyager.html ] 1 spacecraft looked back toward the inner solar system to record this startling view [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA00335 ] of Saturn's nightside. The picture was taken on November 16, 1980, some four days after the robot spacecraft's closest approach to the gorgeous gas giant [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/saturn.html ]. The crescent planet casts a broad shadow [ http://antwrp.gsfc.nasa.gov/apod/ap000212.html ] across its bright rings while the translucent rings themselves can be seen to cast a shadow on Saturn's cloud tops [ http://antwrp.gsfc.nasa.gov/apod/ap951018.html ]. Since Earth is closer to the sun than Saturn [ http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-saturn.html ], only Saturn's dayside is visible to Earth-bound telescopes [ http://www.seds.org/billa/bigeyes.html ] which could never take a picture like this one. After this successful [ http://vraptor.jpl.nasa.gov/voyager/vgrsat_fs.html ] flyby two decades ago, Voyager 1 has continued outward bound [ http://vraptor.jpl.nasa.gov/flteam/weekly-rpts/current.html ] and is presently humanity's most distant spacecraft [ http://vraptor.jpl.nasa.gov/voyager/ vimdesc.html ]. The next spacecraft to approach Saturn will be Cassini [ http://www.jpl.nasa.gov/cassini/ ], on course to arrive in 2004.
Venus, Moon, and Neighbors
Title Venus, Moon, and Neighbors
Explanation Rising before the Sun on February 2nd, astrophotographer [ http://pages.prodigy.net/pam.orman/JoeGallery.html ] Joe Orman anticipated [ http://pages.prodigy.net/pam.orman/JoeAlmanac2000.html ] this apparition of the bright morning star [ http://ispec.scibernet.com/station/morn_star.html ] Venus near a lovely crescent Moon above a neighbor's house in suburban Phoenix, Arizona, USA. Fortunately, the alignment of bright planets and the Moon is one of the most inspiring sights in the night sky [ http://www.skypub.com/sights/skyevents/0004skyevents.html ] and one that is often easy to enjoy and share without any special equipment. Take tonight [ http://spacescience.com/headlines/y2000/ast30mar_1m.htm ], for example. Those blessed with clear skies can simply step outside near sunset and view a young crescent Moon very near three bright planets in the west Jupiter [ http://galileo.jpl.nasa.gov/ ], Mars [ http://mars.jpl.nasa.gov/mgs/ ], and Saturn [ http://www.jpl.nasa.gov/cassini/ ]. Jupiter will be the unmistakable brightest star near the Moon with a reddish Mars just to Jupiter's north and pale yellow Saturn directly above. Of course, these sky shows [ http://drumright.ossm.edu/astronomy/conjunctions.html ] create an evocative picture [ http://antwrp.gsfc.nasa.gov/apod/ap000310.html ] but the planets and Moon just appear to be near each other -- they are actually only approximately lined up and lie in widely separated orbits. Unfortunately, next month's highly publicized alignment of planets [ http://www.griffithobs.org/SkyAlignments.html ] on May 5th will be lost from view in the Sun's glare but such planetary alignments [ http://www.skypub.com/news/special/whypanic.html ] occur repeatedly and pose no danger [ http://www.badastronomy.com/bad/misc/planets.html ] to planet Earth.
Saturn-Sized Worlds Discover …
Title Saturn-Sized Worlds Discovered
Explanation The last decade [ http://antwrp.gsfc.nasa.gov/apod/ap991229.html ] saw the profound discovery of many worlds [ http://origins.stsci.edu/news/2000/01/background.html ] beyond our solar system, but none analogs of our home planet Earth [ http://earthobservatory.nasa.gov/ ]. Exploiting precise observational techniques, astronomers inferred [ http://cannon.sfsu.edu/~gmarcy/planetsearch/planetsearch.html ] the presence of well over two dozen extrasolar planets [ http://cfa-www.harvard.edu/planets/ ], most nearly as massive as gas giant Jupiter or more, in close orbits around sun-like stars. Less massive planets must certainly exist, and yesterday preeminent planet-finders announced [ http://origins.stsci.edu/news/2000/01/ index.html ] the further detection of two more new worlds -- each a potentially smaller, saturn-sized planet. The parent [ http://antwrp.gsfc.nasa.gov/apod/ap990611.html ] suns are 79 Ceti (constellation Cetus [ http://www.astro.wisc.edu/~dolan/constellations/ constellations/Cetus.html ]), at a distance of 117 light-years, and HD46375 (constellation Monoceros [ http://www.astro.wisc.edu/~dolan/ constellations/constellations/Monoceros.html ]), 109 light-years away. With at least 70 percent the mass of Saturn, 79 Ceti's planet orbits [ http://origins.stsci.edu/news/2000/01/animations.html ] on average 32.5 million miles from the star compared to 93 million miles for the Earth-Sun distance [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ]. This arresting artist's vision depicts the newly discovered world with rings and moons, known characteristics of giant planets in our solar system. HD46375's planet is at least 80 percent Saturn's mass, orbiting only 3.8 million miles from its parent star. While Saturn's [ http://nssdc.gsfc.nasa.gov/planetary/ factsheet/saturnfact.html ] mass is only one third of Jupiter's [ http://nssdc.gsfc.nasa.gov/planetary/ factsheet/jupiterfact.html ], it is still about 100 times that of Earth, and dramatic discoveries in the search [ http://tpf.jpl.nasa.gov/ ] for smaller planets are still to come [ http://sim.jpl.nasa.gov/science/ planet.html ].
Planets Above The Clouds
Title Planets Above The Clouds
Explanation Clouds scatter the faint orange rays of the setting sun [ http://antwrp.gsfc.nasa.gov/apod/ap000115.html ] in the foreground of this breathtaking photograph from the summit [ http://www.ifa.hawaii.edu/mko/mko.html ] of Mauna Kea, Hawaii [ http://antwrp.gsfc.nasa.gov/apod/ap980725.html ]. Taken on April 7th, this skyscape features a dramatic lunar and planetary alignment [ http://antwrp.gsfc.nasa.gov/apod/ap000406.html ]. An overexposed crescent moon [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ] dominates the celestial scene, but the bright "star" just below and to its right is Saturn [ http://www.jpl.nasa.gov/cassini/Kids/stories/ ] while further below Saturn is a close pairing of brilliant Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap000429.html ] and a fainter, yellowish Mars [ http://marsnt3.jpl.nasa.gov/education/students.html ]. Red giant star Aldebaran [ http://www.bo.astro.it/copernic/alde-eng.html ] is almost directly above the moon near the top of the image and the bright blue stars of the Pleiades cluster [ http://www.aao.gov.au/images.html/captions/uks018.html ] are visible about midway up and to the right of the moon-Aldebaran line. The good news is that planetary alignments [ http://www.skypub.com/news/special/whypanic.html ] like this one do not portend [ http://tech-two.mit.edu/Shakespeare/Tragedy/macbeth/ macbeth.html ] disasters, are relatively common, and can clearly make inspirational viewing for casual stargazers and astronomers alike. The bad [ http://www.badastronomy.com/bad/misc/planets.html ] news is that the world is not going to end because of the highly publicized planetary alignment [ http://www.griffithobs.org/SkyAlignments.html ] occurring tomorrow, May 5th -- so you probably will have to go to work [ http://www.nasa.gov/newsinfo/alignment.html ]!
Exploring Comet Tails
Title Exploring Comet Tails
Explanation Comets [ http://seds.lpl.arizona.edu/billa/tnp/comets.html ] are known for their tails. In the spring [ http://antwrp.gsfc.nasa.gov/apod/ap970320.html ] of 1997 and 1996 Comet Hale-Bopp [ http://encke.jpl.nasa.gov/hale_bopp_info.html ] (above) and Comet Hyakutake [ http://encke.jpl.nasa.gov/comets_long/96B2.html ] gave us stunning examples [ http://pages.prodigy.net/pam.orman/JoeGallery.html ] as they passed near the Sun. These extremely active comets [ http://antwrp.gsfc.nasa.gov/apod/ap980410.html ] were bright, naked-eye spectacles offering researchers an opportunity to telescopically [ http://encke.jpl.nasa.gov/ ] explore the composition of primordial chunks of our solar system by studying their long and beautiful tails. But it has only recently been discovered that surprising readings [ ftp://ftp.hq.nasa.gov/pub/pao/pressrel/2000/00-055.txt ] from experiments on-board the interplanetary Ulysses probe [ http://ulysses.jpl.nasa.gov ] which lasted for several hours on May 1, 1996, indicate the probe passed through [ http://www.sp.ph.ic.ac.uk/Ulysses/comet/ ] comet Hyakutake's tail! Ulysses experiments were intended [ http://ulysses.jpl.nasa.gov/science/objectives.html ] to study the Sun and solar wind and the spacecraft-comet [ http://stardust.jpl.nasa.gov/ ] encounter was totally unanticipated. Relative positions of Ulysses [ http://ulysses-ops.jpl.esa.int/ulysses/ ] and Hyakutake on that date indicate that this comet's ion tail [ http://antwrp.gsfc.nasa.gov/apod/ap960319.html ] stretched an impressive 360 million miles or about four times the Earth-Sun distance [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ]. This makes Hyakutake's tail the longest ever recorded [ http://heasarc.gsfc.nasa.gov/docs/heasarc/missions/isee3.html ] and suggests that comet tails [ http://antwrp.gsfc.nasa.gov/apod/ap960327.html ] are much longer than previously believed.
Pleiades, Planets, And Hot P …
Title Pleiades, Planets, And Hot Plasma
Explanation Bright stars of the Pleiades, four planets, and erupting solar plasma are all captured in this spectacular image [ http://sohowww.nascom.nasa.gov/hotshots/ ] from the space-based SOlar and Heliospheric Observatory (SOHO). In the foreground of the 15 degree wide field of view, a bubble of hot plasma, called a Coronal Mass Ejection (CME [ http://antwrp.gsfc.nasa.gov/apod/ap000309.html ]), is blasting away from the active Sun [ http://www.spaceweather.com/ ] whose position and relative size is indicated by the central white circle. Beyond [ http://sohowww.nascom.nasa.gov/hotshots/2000_05_03/ diagram1.jpg ] appear four of the five [ http://antwrp.gsfc.nasa.gov/apod/ap000505.html ] naked-eye planets [ http://sse.jpl.nasa.gov/features/planets/ planetsfeat.html ] -- courtesy [ http://www.badastronomy.com/bad/misc/planets.html ] of the planetary alignment [ http://science.nasa.gov/headlines/y2000/ ast30mar_1m.htm#alignments ] which did not destroy the world! In the background are distant stars and the famous Pleiades [ http://www.seds.org/messier/m/m045.html ] star cluster, also easily visible to the unaided eye when it shines in the night sky [ http://antwrp.gsfc.nasa.gov/apod/ap000504.html ]. Distances for these familiar [ http://www.seds.org/nineplanets/nineplanets/ nineplanets.html ] celestial objects are, the Sun [ http://helios.gsfc.nasa.gov/sun.html ], 150 million kilometers away, Mercury, Venus, Jupiter, and Saturn, about 58, 110, 780, and 1,400 million kilometers beyond the Sun respectively, and the Pleiades [ http://www.ras.ucalgary.ca/~gibson/pleiades/ ] star cluster at a mere 3,800 trillion kilometers (400 light-years). SOHO itself orbits 1.5 million kilometers sunward of planet Earth. The image [ http://sohowww.nascom.nasa.gov/data/latestimages.html ] was recorded by the Large Angle and Spectrometric COronagraph (LASCO) instrument on board SOHO on Monday, May 15 at 10:42 UT.
The View toward Husband Hill …
Title The View toward Husband Hill on Mars
Explanation This Martian vista [ http://photojournal.jpl.nasa.gov/catalog/PIA08527 ] is only part of one of the greatest panoramic views of Mars [ http://antwrp.gsfc.nasa.gov/apod/ap000514.html ] that has ever been attempted. The expansive mosaic is helping to keep the robotic Spirit rover [ http://en.wikipedia.org/wiki/MER-A ] busy over the energy draining winter in the southern hemisphere of Mars [ http://antwrp.gsfc.nasa.gov/apod/ap030602.html ]. During the winter, Spirit is constrained to stay on the side of McCool Hill [ http://antwrp.gsfc.nasa.gov/apod/ap060315.html ] in order to keep its solar panels [ http://www.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12490 ] pointed toward the Sun [ http://en.wikipedia.org/wiki/Sun ]. The panorama has so far involved over 800 exposures, very little digital compression [ http://en.wikipedia.org/wiki/Image_compression ], and will take over a month to complete. The view shown is toward Husband Hill [ http://antwrp.gsfc.nasa.gov/apod/ap051114.html ], a hill that Spirit climbed last year. A careful inspection of the above image [ http://photojournal.jpl.nasa.gov/catalog/PIA08527 ] shows tracks crossing [ http://antwrp.gsfc.nasa.gov/apod/ap040922.html ] from the center to the right.
Crescent Rhea Occults Cresce …
Title Crescent Rhea Occults Crescent Saturn
Explanation Soft hues, partially lit orbs, a thin trace of the ring, and slight shadows highlight this understated view of the majestic surroundings of the giant planet Saturn. Looking nearly back toward the Sun, the robot Cassini spacecraft [ http://en.wikipedia.org/wiki/Cassini-Huygens ] now orbiting Saturn captured crescent phases [ http://antwrp.gsfc.nasa.gov/apod/ap060618.html ] of Saturn [ http://www.nineplanets.org/saturn.html ] and its moon Rhea [ http://antwrp.gsfc.nasa.gov/apod/ap060530.html ] in color a few months ago. As striking as the above image [ http://photojournal.jpl.nasa.gov/catalog/PIA07806 ] is, it is but a single frame from a recently released 60-frame silent movie where Rhea can be seen gliding in front of its parent world. Since Cassini was nearly in the plane of Saturn's rings [ http://pds-rings.seti.org/saturn/ ], the normally impressive rings are visible here only as a thin line [ http://antwrp.gsfc.nasa.gov/apod/ap051219.html ] across the image center. Cassini has now passed the official half-way mark of its mission around Saturn, but is well situated to complete another two years [ http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=670 ] investigating this complex and surprising system.
Planets In The Sun
Title Planets In The Sun
Explanation Today [ http://science.nasa.gov/headlines/y2000/ast02may_1.htm ], all five naked-eye planets [ http://www.seds.org/nineplanets/nineplanets/ ] (Mercury, Venus, Mars, Jupiter, Saturn) plus the Moon and the Sun [ http://helios.gsfc.nasa.gov/ sun.html ] will at least approximately line-up. As viewed [ http://drumright.ossm.edu/astronomy/conjunctions.html ] from planet Earth, they will be clustered within about 26 degrees, the closest alignment for all these celestial bodies [ http://science.nasa.gov/headlines/y2000/ ast30mar_1m.htm#alignments ] since February 1962, when there was a solar eclipse [ http://antwrp.gsfc.nasa.gov/apod/ap990818.html ]! Such planetary alignments [ http://www.griffithobs.org/SkyAlignments.html ] are not dangerous, except of course that the Sun might hurt your eyes when you look at it [ http://antwrp.gsfc.nasa.gov/apod/ap981212.html ]. So it might be easier [ http://sohowww.nascom.nasa.gov/hotshots/ ] to appreciate today's solar system [ http://space.jpl.nasa.gov/ ] spectacle if
Dog-Bone Shaped Asteroid 216 …
Title Dog-Bone Shaped Asteroid 216 Kleopatra
Explanation An asteroid [ http://www.seds.org/nineplanets/nineplanets/asteroids.html ] the size of New Jersey [ http://www.state.nj.us/ ] that orbits the Sun [ http://antwrp.gsfc.nasa.gov/apod/sun.html ] between Mars [ http://www.solarviews.com/eng/mars.htm ] and Jupiter [ http://www.jpl.nasa.gov/galileo/jupiter/jupiter.html ] has been discovered to have an unusual dog-bone shape. Asteroid 216 Kleopatra [ http://echo.jpl.nasa.gov/~ostro/kle/index.html ], recently mapped with Earth-based radar [ http://www-paoc.mit.edu/Radar_Lab/FAQ.html ], reflects radio waves [ http://imagers.gsfc.nasa.gov/ems/radio.html ] so well that astronomers speculate [ http://echo.jpl.nasa.gov/~ostro/kle/jpl_press_release ] it is composed mostly of metals such as nickel [ http://pearl1.lanl.gov/periodic/elements/28.html ] and iron [ http://www.webelements.com/webelements/scholar/elements/iron/key.html ]. The unusual shape and composition of 216 Kleopatra [ http://sc6.sc.eso.org/~fmarchis/Science/Kleopatra/ ] may derive from the central regions of a tremendous collision between larger asteroids [ http://antwrp.gsfc.nasa.gov/apod/asteroids.html ] billions of years ago. Kleopatra [ http://www.space.com/scienceastronomy/solarsystem/dogbone_asteroid_000505.html ] is not completely solid - its surface is loosely consolidated rubble, although its core may contain large solid-metal lodes. Kleopatra [ http://www.spaceref.com/news/viewnews.html?id=131 ] will never strike the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap980313.html ], but it may one day serve as a valuable source of raw building materials.
The Far Infrared Sky
Title The Far Infrared Sky
Explanation Three major sources contribute to the far-infrared [ http://www.ipac.caltech.edu/Outreach/Edu/discovery.html ] sky [ http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/multiw_sky.html ]: our Solar System [ http://www.seds.org/nineplanets/nineplanets/overview.html ], our Galaxy [ http://antwrp.gsfc.nasa.gov/apod/milky_way.html ], and our Universe [ http://antwrp.gsfc.nasa.gov/apod/ap000312.html ]. The above recently released image [ http://www.astro.ucla.edu/~wright/CIBR/images.html ], in representative colors, is the highest resolution projection yet created of the entire far-infrared sky [ http://www.astro.ucla.edu/~wright/old_new_cosmo.html#FIRB ] (60 - 240 microns) created from years of observations by the now-defunct robot spacecraft COBE [ http://space.gsfc.nasa.gov/astro/cobe/ ]. Our Solar System is evidenced most prominently by the S-shaped blue sash called zodiacal light [ http://antwrp.gsfc.nasa.gov/apod/ap990613.html ], created by small pieces of rock and dust [ http://antwrp.gsfc.nasa.gov/apod/ap981121.html ] orbiting between the Sun [ http://antwrp.gsfc.nasa.gov/apod/sun.html ] and Jupiter [ http://www.jpl.nasa.gov/galileo/jupiter/jupiter.html ]. The disk of our Galaxy [ http://adc.gsfc.nasa.gov/mw/milkyway.html ] is evidenced most prominently by the thin band of light-emitting dust [ http://antwrp.gsfc.nasa.gov/apod/ap990509.html ] that crosses the middle of the image. Clouds and filaments of dust in our Milky Way [ http://antwrp.gsfc.nasa.gov/apod/ap971229.html ] also make intricate patterns pervading most of the sky. Close inspection of similar images reveal [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998ApJ...500..525S ] that the background is not completely dark, indicating that our Universe itself provides a diffuse glow [ http://antwrp.gsfc.nasa.gov/apod/ap980121.html ], created by dust left over from the star formation throughout the Universe [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998ApJ...508..106D ].
Ganymede: The Largest Moon i …
Title Ganymede: The Largest Moon in the Solar System
Explanation If Ganymede orbited the Sun, it would be considered a planet. The reason is that Jupiter [ http://galileo.jpl.nasa.gov/jupiter/jupiter.html ]'s moon Ganymede [ http://www.seds.org/nineplanets/nineplanets/ganymede.html ] is not only the largest moon in the Solar System [ http://www.seds.org/nineplanets/nineplanets/datamax.html ], it is larger than planets Mercury [ http://www.seds.org/nineplanets/nineplanets/mercury.html ] and Pluto [ http://dosxx.colorado.edu/plutohome.html ]. The robot spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/overview.html ] currently orbiting Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] has been able to zoom by Ganymede [ http://www.solarviews.com/eng/ganymede.htm ] several times and snap many close-up pictures. Ganymede, shown above [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA00716 ] in its natural colors, sports a large oval dark region known as Galileo Regio [ http://www.jpl.nasa.gov/galileo/ganymede/121896.html ]. In general, the dark regions on Ganymede [ http://sse.jpl.nasa.gov/features/planets/jupiter/ganymede.html ] are heavily cratered, implying they are very old, while the light regions are younger and dominated by unusual grooves [ http://antwrp.gsfc.nasa.gov/apod/ap960711.html ]. The origin of the grooves is still under investigation [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998Icar..135..317P ].
Saturn at Night
Title Saturn at Night
Explanation This is what Saturn looks like at night. In contrast to the human-made lights [ http://antwrp.gsfc.nasa.gov/apod/ap040822.html ] that cause the nighttime side of Earth to glow faintly, Saturn's faint nighttime glow is primarily caused by sunlight reflecting off of its own majestic rings [ http://antwrp.gsfc.nasa.gov/apod/ap050525.html ]. The above image [ http://photojournal.jpl.nasa.gov/catalog/PIA08252 ] of Saturn at night was captured in July by the Cassini spacecraft [ http://saturn.jpl.nasa.gov/spacecraft/index.cfm ] now orbiting Saturn. The above image [ http://photojournal.jpl.nasa.gov/catalog/PIA08252 ] was taken when the Sun was far in front of the spacecraft. From this vantage point, the northern hemisphere of nighttime Saturn, visible on the left, appears eerily dark. Sunlit rings are visible ahead, but are abruptly cut off by Saturn [ http://en.wikipedia.org/wiki/Saturn ]'s shadow. In Saturn's southern hemisphere, visible on the right, the dim reflected glow from the sunlit rings is most apparent. Imprinted on this diffuse glow, though, are thin black stripes not discernable to any Earth telescope [ http://antwrp.gsfc.nasa.gov/apod/ap971227.html ] -- the silhouetted C ring [ http://en.wikipedia.org/wiki/Saturn%27s_rings ] of Saturn. Cassini has been orbiting Saturn since 2004 and its mission [ http://en.wikipedia.org/wiki/Cassini-Huygens ] is scheduled to continue until 2008.
MyCn18: An Hourglass Nebula
Title MyCn18: An Hourglass Nebula
Explanation The sands of time are running out for the central star of this hourglass-shaped planetary nebula [ http://fusedweb.pppl.gov/CPEP/ Chart_Pages/5.Plasmas/Nebula/Planetary.html ]. With its nuclear fuel [ http://fusedweb.pppl.gov/default.html ] exhausted, this brief, spectacular, closing phase of a Sun-like star's life [ http://observe.ivv.nasa.gov/nasa/space/stellardeath/stellardeath_contents.html ] occurs as its outer layers are ejected - its core becoming a cooling, fading White Dwarf [ http://antwrp.gsfc.nasa.gov/apod/ap971102.html ]. Astronomers have recently used the Hubble Space Telescope [ http://hubble.stsci.edu/ ] (HST) to make a series of images of planetary nebulae [ http://antwrp.gsfc.nasa.gov/apod/planetary_nebulae.html ], including the one above [ http://www.stsci.edu/pubinfo/PR/96/07.html ]. Here, delicate rings of colorful glowing gas (nitrogen-red, hydrogen-green, and oxygen-blue) outline the tenuous walls of the "hourglass". The unprecedented sharpness of the HST images has revealed surprising details [ http://www.stsci.edu/pubinfo/gif/Hourgls.txt ] of the nebula ejection process [ http://antwrp.gsfc.nasa.gov/apod/ap960117.html ] and may help resolve the outstanding mystery of the variety of complex shapes and symmetries of planetary nebulae [ http://www.astro.washington.edu/balick/WFPC2/index.html ].
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