Galerie de photos de Ganymède, satellite galiléen de la planète Jupiter

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<h1>PIA00081: Ganymede Mosaic</h1><div class="PIA00081" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The hemisphere of Ganymede that faces away from the Sun displays a great variety of terrain. In this Voyager 2 mosaic, photographed at a range of 300,000 kilometers, the ancient dark area of Regio Galileo lies at the upper left. Below it, the ray system is probably caused by water-ice, splashed out in a relatively recent impact.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00081" onclick="window.open(this.href); return false;" title="Voir l'image PIA00081: Ganymede Mosaic sur le site de la NASA">Voir l'image PIA00081: Ganymede Mosaic sur le site de la NASA.</a></div>
PIA00081: Ganymede Mosaic
<h1>PIA00273: Optical Navigation Image of Ganymede</h1><div class="PIA00273" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">NASA's Galileo spacecraft, now in orbit around Jupiter, returned this optical navigation image June 3, 1996, showing that the spacecraft is accurately targeted for its first flyby of the giant moon Ganymede on June 27. The missing data in the frame is the result of a special editing feature recently added to the spacecraft's computer to transmit navigation images more quickly. This is first in a series of optical navigation frames, highly edited onboard the spacecraft, that will be used to fine-tune the spacecraft's trajectory as Galileo approaches Ganymede. The image, used for navigation purposes only, is the product of new computer processing capabilities on the spacecraft that allow Galileo to send back only the information required to show the spacecraft is properly targeted and that Ganymede is where navigators calculate it to be. "This navigation image is totally different from the pictures we'll be taking for scientific study of Ganymede when we get close to it later this month," said Galileo Project Scientist Dr. Torrence Johnson. On June 27, Galileo will fly just 844 kilometers (524 miles) above Ganymede and return the most detailed, full-frame, high-resolution images and other measurements of the satellite ever obtained. Icy Ganymede is the largest moon in the solar system and three-quarters the size of Mars. It is one of the four large Jovian moons that are special targets of study for the Galileo mission. Of the more than 5 million bits contained in a single image, Galileo performed on-board editing to send back a mere 24,000 bits containing the essential information needed to assure proper targeting. Only the light-to-dark transitions of the crescent Ganymede and reference star locations were transmitted to Earth. The navigation image was taken from a distance of 9.8 million kilometers (6.1 million miles). On June 27th, the spacecraft will be 10,000 times closer to Ganymede.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00273" onclick="window.open(this.href); return false;" title="Voir l'image PIA00273: Optical Navigation Image of Ganymede sur le site de la NASA">Voir l'image PIA00273: Optical Navigation Image of Ganymede sur le site de la NASA.</a></div>
PIA00273: Optical Navigation Image of Ganymede
<h1>PIA00276: Ganymede - Ridges, Grooves, Craters and Smooth Areas of Uruk Sulcus Region</h1><div class="PIA00276" lang="en" style="width:526px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Ridges, grooves, craters and relatively smooth areas in the Uruk Sulcus region of Jupiter's moon Ganymede are shown in this high-resolution image captured by NASA's Galileo spacecraft during its first flyby of Ganymede on June 27, 1996. This image was taken when Galileo was 7,448 kilometers (4.628 miles) away from Ganymede; north is to the top of the picture, and sunlight illuminates the surface from the lower left nearly overhead (77 degrees above the horizon). The area shown, at latitude 10 degrees north, longitude 168 degrees west, is about 55 by 35 kilometers (34 by 25 miles); the smallest features that can be discerned are 74 meters (243 feet). The line-like features are sunlit ridges, often arranged in parallel sets. The patterns of ridges and grooves indicate that extension (pulling apart) and shear (horizontal sliding) have both shaped the icy landscape. The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00276" onclick="window.open(this.href); return false;" title="Voir l'image PIA00276: Ganymede - Ridges, Grooves, Craters and Smooth Areas of Uruk Sulcus Region sur le site de la NASA">Voir l'image PIA00276: Ganymede - Ridges, Grooves, Craters and Smooth Areas of Uruk Sulcus Region sur le site de la NASA.</a></div>
PIA00276: Ganymede - Ridges, Grooves, Craters and Smooth Areas of Uruk Sulcus Region
<h1>PIA00277: Ganymede - Comparison of Voyager and Galileo Resolution</h1><div class="PIA00277" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">These images demonstrate the dramatic improvement in the resolution of pictures that NASA's Galileo spacecraft is returning compared to previous images of the Jupiter system. The frame at left was taken by the Voyager 2 spacecraft when it flew by in 1979, with a resolution of about 1.3 kilometers (0.8 mile) per pixel. The frame at right showing the same area was captured by Galileo during its first flyby of Ganymede on June 27, 1996; it has a resolution of about 74 meters (243 feet) per pixel, more than 17 times better than that of the Voyager image. In the Voyager frame, line-like bright and dark bands can be seen but their detailed structure and origin are not clear. In the Galileo image, each band is now seen to be composed of many smaller ridges. The structure and shape of the ridges permit scientists to determine their origin and their relation to other terrains, helping to unravel the complex history of the planet-sized moon. In each of these frames, north is to the top, and the sun illuminates the surface from the lower left nearly overhead (about 77 degrees above the horizon). The area shown, at latitude 10 degrees north, 167 degrees west, is about 35 by 55 kilometers (25 by 34 miles). The image was taken June 27 when Galileo was 7,448 kilometers (4.628 miles) away from Ganymede. The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00277" onclick="window.open(this.href); return false;" title="Voir l'image PIA00277: Ganymede - Comparison of Voyager and Galileo Resolution sur le site de la NASA">Voir l'image PIA00277: Ganymede - Comparison of Voyager and Galileo Resolution sur le site de la NASA.</a></div>
PIA00277: Ganymede - Comparison of Voyager and Galileo Resolution
<h1>PIA00278: Ganymede - Dark Terrain in Galileo Regio</h1><div class="PIA00278" lang="en" style="width:640px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This view of a part of the Galileo Regio region on Jupiter's moon Ganymede shows fine details of the dark terrain that makes up about half of the surface of the planet-sized moon. One of many ancient impact craters in the region is visible at the middle left. The crater is cut by numerous fractures, showing that the ancient crust was highly deformed early in Ganymede's history. Dark areas may have originated from dark material thrown off by dark meteorites hitting the surface in thousands of impact events. In this view, north is to the top and the sun illuminates the surface from the lower left about 58 degrees above the horizon. The area shown, at latitude 19 degrees north, longitude 149 degrees west, is about 19 by 26 kilometers (12 by 16 miles); resolution is about 80 meters (262 feet) per pixel. The image was taken June 27 at a range of 7.652 kilometers (4,755 miles). The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00278" onclick="window.open(this.href); return false;" title="Voir l'image PIA00278: Ganymede - Dark Terrain in Galileo Regio sur le site de la NASA">Voir l'image PIA00278: Ganymede - Dark Terrain in Galileo Regio sur le site de la NASA.</a></div>
PIA00278: Ganymede - Dark Terrain in Galileo Regio
<h1>PIA00279: Ganymede - Ancient Impact Craters in Galileo Regio</h1><div class="PIA00279" lang="en" style="width:574px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Ancient impact craters shown in this image of Jupiter's moon Ganymede taken by NASA's Galileo spacecraft testify to the great age of the terrain, dating back several billion years. At the margin at the left, half of a 19-kilometer-diameter (12-mile) crater is visible. The dark and bright lines running from lower right to upper left and from top to bottom are deep furrows in the ancient crust of dirty water ice. The origin of the dark material is unknown, but it may be accumulated dark fragments from many meteorites that hit Ganymede. In this view, north is to the top, and the sun illuminates the surface from the lower left about 58 degrees above the horizon. The area shown is part of Ganymede's Galileo Regio region at latitude 18 degrees north, longitude 147 degrees west; it is about 46 by 64 kilometers (29 by 38 miles) in extent. Resolution is about 80 meters (262 feet) per pixel. The image was taken June 27 at a range of 7.563 kilometers (4,700 miles). The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00279" onclick="window.open(this.href); return false;" title="Voir l'image PIA00279: Ganymede - Ancient Impact Craters in Galileo Regio sur le site de la NASA">Voir l'image PIA00279: Ganymede - Ancient Impact Craters in Galileo Regio sur le site de la NASA.</a></div>
PIA00279: Ganymede - Ancient Impact Craters in Galileo Regio
<h1>PIA00280: Ganymede - Mixture of Terrains and Large Impact Crater in Uruk Sulcus Region</h1><div class="PIA00280" lang="en" style="width:544px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">A mixture of terrains studded with a large impact crater is shown in this view of the Uruk Sulcus region of Jupiter's moon Ganymede taken by NASA's Galileo spacecraft during its first flyby of the planet-sized moon on June 27, 1996. The image shows fine details of bright areas that make up about half of the surface of Ganymede. Pock-marked, ancient, heavily cratered terrain is seen at the top; it is cut by younger, line-like structures in the lower left of the image. The bright, circular feature in the lower middle is an impact crater with some dark ejecta superimposed on the linear ridges. These types of relationships revealed by Galileo allow scientists to work out the complex geologic history of Ganymede. In this view, north is to the top and the sun illuminates the surface from the lower left nearly overhead. The area shown, at latitude 10 degrees north, longitude 168 degrees west, is about 59 by 40 kilometers (36 by 25 miles), and the resolution is 74 meters (80 yards) per picture element. The image was taken on June 27 at a range of 7,448 kilometers (4.628 miles). The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00280" onclick="window.open(this.href); return false;" title="Voir l'image PIA00280: Ganymede - Mixture of Terrains and Large Impact Crater in Uruk Sulcus Region sur le site de la NASA">Voir l'image PIA00280: Ganymede - Mixture of Terrains and Large Impact Crater in Uruk Sulcus Region sur le site de la NASA.</a></div>
PIA00280: Ganymede - Mixture of Terrains and Large Impact Crater in Uruk Sulcus Region
<h1>PIA00281: Ganymede - Galileo Mosaic Overlayed on Voyager Data in Uruk Sulcus Region</h1><div class="PIA00281" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">A mosaic of four Galileo high-resolution images of the Uruk Sulcus region of Jupiter's moon Ganymede is shown within the context of an image of the region taken by Voyager 2 in 1979. The image shows details of parallel ridges and troughs that are the principal features in the brighter regions of Ganymede. The Galileo frames unveil the fine-scale topography of Ganymede's ice-rich surface, permitting scientists to develop a detailed understanding of the processes that have shaped Ganymede. Resolution of the Galileo images is 74 meters (243 feet) per pixel, while resolution of the Voyager image is 1.3 kilometers (0.8 mile) per pixel. In this view, north is to the top, and the sun illuminates the surface from the lower left nearly overhead. The area shown, at latitude 10 degrees north, longitude 168 degrees west, is about 120 by 110 kilometers (75 by 68 miles) in extent. The image was taken June 27 at a range of 7,448 kilometers (4,628 miles). The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00281" onclick="window.open(this.href); return false;" title="Voir l'image PIA00281: Ganymede - Galileo Mosaic Overlayed on Voyager Data in Uruk Sulcus Region sur le site de la NASA">Voir l'image PIA00281: Ganymede - Galileo Mosaic Overlayed on Voyager Data in Uruk Sulcus Region sur le site de la NASA.</a></div>
PIA00281: Ganymede - Galileo Mosaic Overlayed on Voyager Data in Uruk Sulcus Region
<h1>PIA00334: Crater Rays on Ganymede</h1><div class="PIA00334" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This mosaic of Voyager 2 images taken July 9, 1979, shows a prominent rayed crater on Jupiter's icy moon, Ganymede. The view on the left is a monochrome image, and that on the right is the same scene shown in false color designed to accentuate the icy ejecta rays splashed out by the impact. This crater is about 150 km (93 miles) across. Like several other large craters in this scene, the rayed one has a central pit, whose origins remain speculative but may involve impact melting or solid-state fluidization of the icy crust. Bright crater rays on Ganymede, like those on our own Moon, are useful to geologists because they constitute a set of features that were laid across the moon's surface at a discrete point in time--thus they serve as time markers that can be used to establish the sequence of events that shaped Ganymede's surface. For instance, the crater rays appear to be painted over, hence are younger than, areas of grooved terrain (lower left quadrant), whereas a somewhat smaller crater at the center of the scene has icy ejecta that appears to bury (hence, post-dates) the large crater ray system. One can conclude that the grooved terrain formed first, then the large crater and its rays, and then the smaller crater and its fresh icy ejecta deposits.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00334" onclick="window.open(this.href); return false;" title="Voir l'image PIA00334: Crater Rays on Ganymede sur le site de la NASA">Voir l'image PIA00334: Crater Rays on Ganymede sur le site de la NASA.</a></div>
PIA00334: Crater Rays on Ganymede
<h1>PIA00351: Ganymede at 2.6 million miles</h1><div class="PIA00351" lang="en" style="width:300px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This photo of Ganymede, largest of Jupiter's Galilean satellites and the third from the planet, was taken shortly after midnight March 1, from a distance of 2.6 million miles (4.2 million kilometers). Ganymede is slightly larger than the planet Mercury, but is much less dense; it has = roughly twice the density of water. Ganymede's surface brightness is = four times that of Earth's Moon. This photo shows dark features = reminiscent of the dark, mare regions on the Moon. On Ganymede, however, = these features have twice the brightness of lunar mare. Scientists = believe they are unlikely to be composed of rock or lava as the Moon's = mare regions are. Ganymede's north polar region appears to be covered = with brighter material, and scientists say it could be water frost. = Later photos of Ganymede will be taken from closer range and will = therefore have higher resolution if those photos of the polar region show = underlying terrain blanketed by frost, it could indicate movement of water= across Ganymede's surface, possibly in a very thin atmosphere. Brighter = spots are also scattered across this hemisphere of Ganymede. They may be = related to impact craters, or may represent source regions of fresh ice. = JPL manages and controls the Voyager project for NASA's Office of Space = Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00351" onclick="window.open(this.href); return false;" title="Voir l'image PIA00351: Ganymede at 2.6 million miles sur le site de la NASA">Voir l'image PIA00351: Ganymede at 2.6 million miles sur le site de la NASA.</a></div>
PIA00351: Ganymede at 2.6 million miles
<h1>PIA00352: Ganymede at 3.4 million miles</h1><div class="PIA00352" lang="en" style="width:300px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This color picture of Ganymede, Jupiter's largest satellite, was taken on the afternoon of March 2, 1979, by Voyager 1 from a distance of about 3.4 million kilometers (2.1 million miles). This photograph was assembled from three black-and-white pictures in the Image Processing Laboratory at JPL. This face of Ganymede is centered on the 260=B0 meridian. Ganymede is slightly larger than the planet Mercury but has a density almost three times less than Mercury. Therefore, Ganymede probably consists in large part of ice. At this resolution the surface shows light and dark markings interspersed with bright spots. The large darkish area near the center of the satellite is crossed by irregular light streaks somewhat similar to rays seen on the Moon. The bright patch in the southern hemisphere is reminiscent of some of the larger rayed craters on the Moon caused by meteorite impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00352" onclick="window.open(this.href); return false;" title="Voir l'image PIA00352: Ganymede at 3.4 million miles sur le site de la NASA">Voir l'image PIA00352: Ganymede at 3.4 million miles sur le site de la NASA.</a></div>
PIA00352: Ganymede at 3.4 million miles
<h1>PIA00353: Ganymede Full Disk</h1><div class="PIA00353" lang="en" style="width:600px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture was taken on March 4, 1979 at 2:30 A.M. PST by Voyager 1 from a distance of 2.6 million kilometers (1.6 million miles). Ganymede is Jupiter's largest satellite with a radius of about 2600 kilometers, about 1.5 times that of our Moon. Ganymede has a bulk density of only approximately 2.0 g/cc almost half that of the Moon. Therefore, Ganymede is probably composed of a mixture of rock and ice. The features here, the large dark regions, in the northeast quadrant, and the white spots, resemble features found on the Moon, mare and impact craters respectively. The long white filaments resemble rays associated with impacts on the lunar surface. The various colors of different regions probably represent differing surface materials. There are several dots on the picture of single color (blue, green, and orange) which are the result of markings on the camera used for pointing determinations and are not physical markings. JPL manages and controls the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00353" onclick="window.open(this.href); return false;" title="Voir l'image PIA00353: Ganymede Full Disk sur le site de la NASA">Voir l'image PIA00353: Ganymede Full Disk sur le site de la NASA.</a></div>
PIA00353: Ganymede Full Disk
<h1>PIA00354: Ganymede at 87,000 miles</h1><div class="PIA00354" lang="en" style="width:460px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture of Ganymede, Jupiter's largest satellite was taken on the afternoon of March 5, 1979 from a range 145,000 km (87,000 mi). The width of the picture represents about 580 km (548 mi.) on the surface of Ganymede, and the smallest visible features are about 3 km (1.7 mi) across. The picture shows complex patterns of ridges and grooves which are probably the results of deformations of Ganymede's thick icy crust. Some systems of grooves and ridges are superposed on the ridge and groove systems indicating they are younger. A more degraded crater near the left center of the picture is crossed by ridges indicated that it predates the period of crystal deformation. JPL manages and controls the Voyager Project of NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00354" onclick="window.open(this.href); return false;" title="Voir l'image PIA00354: Ganymede at 87,000 miles sur le site de la NASA">Voir l'image PIA00354: Ganymede at 87,000 miles sur le site de la NASA.</a></div>
PIA00354: Ganymede at 87,000 miles
<h1>PIA00356: Ganymede's Northern Hemisphere</h1><div class="PIA00356" lang="en" style="width:740px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This color reconstruction of part of the northern hemisphere of Ganymede was made from pictures taken at a range of 313,000 kilometers (194,000 miles). The scene is approximately 1,300 kilometers (806 miles) across. It shows part of dark, densely cratered block which is bound on the south by lighter, and less cratered, grooved terrain. The dark blocks are believed to be the oldest parts of Ganymede's surface. Numerous craters are visible, many with central peaks. The large bright circular features have little relief and are probably the remnants of old, large craters that have been annealed by flow of the icy near-surface material. The closely-spaced arcuate, linear features are probably analogous to similar features on Ganymede which surround a large impact basin. The linear features here may indicate the former presence of a large impact basin to the southwest.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00356" onclick="window.open(this.href); return false;" title="Voir l'image PIA00356: Ganymede's Northern Hemisphere sur le site de la NASA">Voir l'image PIA00356: Ganymede's Northern Hemisphere sur le site de la NASA.</a></div>
PIA00356: Ganymede's Northern Hemisphere
<h1>PIA00357: Bright Halo Impact Crater on Ganymede</h1><div class="PIA00357" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">his color picture of Ganymede in the region 30 S 180 W shows features as small as 6 kilometers (3.7 miles) across. Shown is a bright halo impact crater that shows the fresh material thrown out of the crater. In the background is bright grooved terrain that may be the result of shearing of the surface materials along fault planes. The dark background material is the ancient heavily cratered terrain -- the oldest material preserved on the Ganymede surface.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00357" onclick="window.open(this.href); return false;" title="Voir l'image PIA00357: Bright Halo Impact Crater on Ganymede sur le site de la NASA">Voir l'image PIA00357: Bright Halo Impact Crater on Ganymede sur le site de la NASA.</a></div>
PIA00357: Bright Halo Impact Crater on Ganymede
<h1>PIA00380: Ganymede At 150,000 Miles</h1><div class="PIA00380" lang="en" style="width:700px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture of Ganymede, Jupiter's largest satellite, was taken by Voyager 1 on the afternoon of March 5, 1979, from a range of about 250,000 km (150,000 mi.). The center of the picture is at 60 north latitude and 318 longitude, and the distance across the bottom of the photograph is about 1000 km (600 mi.). The smallest features visible in this picture are about 5 km (3 mi.) across. This picture shows impact craters many of which display ray systems probably consisting largely of icy material thrown out by the impacts. Peculiar systems of sinuous ridges and grooves traverse the surface and are best seen near the terminator. These ridges and grooves are probably the result of deformation of the thick ice crust on Ganymede. JPL manages and controls the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00380" onclick="window.open(this.href); return false;" title="Voir l'image PIA00380: Ganymede At 150,000 Miles sur le site de la NASA">Voir l'image PIA00380: Ganymede At 150,000 Miles sur le site de la NASA.</a></div>
PIA00380: Ganymede At 150,000 Miles
<h1>PIA00492: Galileo Regio Mosaic - Galileo over Voyager Data</h1><div class="PIA00492" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>A mosaic of four Galileo images of the Galileo Regio region on Ganymede (Latitude 18 N, Longitude: 149 W) is shown overlayed on the data obtained by the Voyager 2 spacecraft in 1979. North is to the top of the picture, and the sun illuminates the surface from the lower left, about 58 degrees above the horizon. The smallest features that can be discerned are about 80 meters (262 feet) in size in the Galileo images. These Galileo images show fine details of the dark terrain that makes up about half of the surface of the planet-sized moon. Ancient impact craters of various sizes and states of degradation testify to the great age of the terrain, dating back several billion years. The images reveal distinctive variations in albedo from the brighter rims, knobs, and furrow walls to a possible accumulation of dark material on the lower slopes, and crater floors. High photometric activity (large light contrast at high spatial frequencies) of this ice-rich surface was such that the Galileo camera's hardware data compressor was pushed into truncating lines. The north-south running gap between the left and right halves of the mosaic is a result of line truncation from the normal 800 samples per line to about 540. The images were taken on 27 June, 1996 Universal Time at a range of 7,580 kilometers (4,738 miles) through the clear filter of the Galileo spacecraft's imaging system. Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00492" onclick="window.open(this.href); return false;" title="Voir l'image PIA00492: Galileo Regio Mosaic - Galileo over Voyager Data sur le site de la NASA">Voir l'image PIA00492: Galileo Regio Mosaic - Galileo over Voyager Data sur le site de la NASA.</a></div>
PIA00492: Galileo Regio Mosaic - Galileo over Voyager Data
<h1>PIA00493: Uruk Sulcus Mosaic - Galileo over Voyager Data</h1><div class="PIA00493" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>A mosaic of four Galileo images of the Uruk Sulcus region on Ganymede (Latitude 11 N, Longitude: 170 W) is shown overlayed on the data obtained by the Voyager 2 spacecraft in 1979. North is to the top of the picture, and the sun illuminates the surface from the lower left, nearly overhead. The area shown is about 120 by 110 kilometers (75 by 68 miles) in extent and the smallest features that can be discerned are 74 meters (243 feet) in size in the Galileo images and 1.3 kilometers (0.8 miles) in the Voyager data. The higher resolution Galileo images unveil the details of parallel ridges and troughs that are principal features in the brighter regions of Ganymede. High photometric activity (large light contrast at high spatial frequencies) of this ice-rich surface was such that the Galileo camera's hardware data compressor was pushed into truncating lines. The north-south running gap between the left and right halves of the mosaic is a result of line truncation from the normal 800 samples per line to about 540. The images were taken on 27 June, 1996 Universal Time at a range of 7,448 kilometers (4,628 miles) through the clear filter of the Galileo spacecraft's imaging system.<p>Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00493" onclick="window.open(this.href); return false;" title="Voir l'image PIA00493: Uruk Sulcus Mosaic - Galileo over Voyager Data sur le site de la NASA">Voir l'image PIA00493: Uruk Sulcus Mosaic - Galileo over Voyager Data sur le site de la NASA.</a></div>
PIA00493: Uruk Sulcus Mosaic - Galileo over Voyager Data
<h1>PIA00496: Ice-frosted crater tops on Ganymede</h1><div class="PIA00496" lang="en" style="width:400px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Scientists believe that water-ice frosts are the likely cause for the brightening seen around the circular rims of these craters located at a high northern latitude (57 degrees) on Jupiter's moon Ganymede in this image taken by NASA's Galileo spacecraft on September 6, 1996. The image, just recently radioed to Earth from the spacecraft, shows the same kind of bright, high-latitude surface areas as those first seen by the Voyager spacecraft in 1979, but at higher resolution (this image spans about 18 kilometers or 11 miles on a side). Even though the Sun is shining from the south, the north-facing walls of the ridges and craters are brighter than the walls facing the Sun. This is interpreted to mean that the very bright north-facing slopes are covered with surface water-ice frosts, and that these frosts preferentially accumulate in such high-latitude locations. Galileo scientists say that at the high resolution seen in Galileo images, the high-latitude brightness seen by Voyager is partly attributable to frosts forming on cooler, north-facing slopes.<p>The right-hand side of the image is dominated by a north-south line of impact craters; the smallest ones at the top are about 2 kilometers (1.2 miles) in diameter and the large one at the bottom is about 5 kilometers (about 3 miles) in diameter. Ganymede is the largest moon in the solar system, larger than the planet Mercury and nearly the size of Mars.<p>The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00496" onclick="window.open(this.href); return false;" title="Voir l'image PIA00496: Ice-frosted crater tops on Ganymede sur le site de la NASA">Voir l'image PIA00496: Ice-frosted crater tops on Ganymede sur le site de la NASA.</a></div>
PIA00496: Ice-frosted crater tops on Ganymede
<h1>PIA00497: Ganymede's Nippur Sulcus</h1><div class="PIA00497" lang="en" style="width:560px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>New terrain overlays older terrain, which overlays still older surface, in this view of part of the surface of Jupiter's moon Ganymede, taken by the camera onboard NASA's Galileo spacecraft. Galileo obtained the images that make up this mosaic when it flew past Jupiter's moon Ganymede for the second time on September 6, 1996. An area about 54 kilometers (33 miles) wide and 90 kilometers (55 miles) high is shown. Northern Marius Regio (the dark terrain at bottom), Philus Sulcus (bright terrain at center), and Nippur Sulcus (bright terrain at top) are seen illuminated by the Sun from the southeast (north is at the top).<p>The key characteristics and relationships of the major terrain types on tectonically active Ganymede are seen at a resolution 16 times better than images taken by the Voyager spacecraft in 1979. At the bottom, the ancient dark terrain is seen to be very deformed by tectonic fractures and faults. An impact crater about 18 kilometers (about 11 miles) in diameter has been highly modified by faulting. More recent cross-cutting fractures and faults at center illustrate to scientists the sequence of events that have created the younger bright terrain. The lines in the middle left of the image are faults that are cross-cut by younger faults in the upper part of the image. The smooth band in the upper middle of the image may represent water-ice volcanic deposits flooding a fault valley. Clusters of small craters, representing ejecta transported from distant craters and re-impacting here, are seen in the middle of the photo. The images that make up this mosaic were taken at a range of about 11,620 kilometers (about 7,200 miles).<p>The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00497" onclick="window.open(this.href); return false;" title="Voir l'image PIA00497: Ganymede's Nippur Sulcus sur le site de la NASA">Voir l'image PIA00497: Ganymede's Nippur Sulcus sur le site de la NASA.</a></div>
PIA00497: Ganymede's Nippur Sulcus
<h1>PIA00519: Ganymede G1 & G2 Encounters - Interior of Ganymede</h1><div class="PIA00519" lang="en" style="width:666px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Voyager images are used to create a global view of Ganymede. The cut-out reveals the interior structure of this icy moon. This structure consists of four layers based on measurements of Ganymede's gravity field and theoretical analyses using Ganymede's known mass, size and density. Ganymede's surface is rich in water ice and Voyager and Galileo images show features which are evidence of geological and tectonic disruption of the surface in the past. As with the Earth, these geological features reflect forces and processes deep within Ganymede's interior. Based on geochemical and geophysical models, scientists expected Ganymede's interior to either consist of: a) an undifferentiated mixture of rock and ice or b) a differentiated structure with a large lunar sized "core" of rock and possibly iron overlain by a deep layer of warm soft ice capped by a thin cold rigid ice crust. Galileo's measurement of Ganymede's gravity field during its first and second encounters with the huge moon have basically confirmed the differentiated model and allowed scientists to estimate the size of these layers more accurately. In addition the data strongly suggest that a dense metallic core exists at the center of the rock core. This metallic core suggests a greater degree of heating at sometime in Ganymede's past than had been proposed before and may be the source of Ganymede's magnetic field discovered by Galileo's space physics experiments.<p>Galileo's primary 24 month mission includes eleven orbits around Jupiter and will provide observations of Jupiter, its moons and its magnetosphere. The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C.<p>This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00519" onclick="window.open(this.href); return false;" title="Voir l'image PIA00519: Ganymede G1 & G2 Encounters - Interior of Ganymede sur le site de la NASA">Voir l'image PIA00519: Ganymede G1 & G2 Encounters - Interior of Ganymede sur le site de la NASA.</a></div>
PIA00519: Ganymede G1 & G2 Encounters - Interior of Ganymede
<h1>PIA00521: Stereo View of Ganymede's Galileo Region</h1><div class="PIA00521" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Topographic detail is seen in this stereoscopic view of the Galileo Regio region of Jupiter's moon Ganymede. The picture is a computer reconstruction from two images taken by NASA's Galileo spacecraft this summer. One image of the Galileo Regio region was taken June 27, 1996, at a range of 9,515 kilometers (about 5,685 miles) with a resolution of 76 meters. The other was taken September 6, 1996 at a range of 10,220 kilometers (about 6,350 miles) with a resolution of 86 meters. The topographic nature of the deep furrows and impact craters that cover this portion of Ganymede is apparent. The blue-sky horizon is artificial.<p>The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C.<p>This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00521" onclick="window.open(this.href); return false;" title="Voir l'image PIA00521: Stereo View of Ganymede's Galileo Region sur le site de la NASA">Voir l'image PIA00521: Stereo View of Ganymede's Galileo Region sur le site de la NASA.</a></div>
PIA00521: Stereo View of Ganymede's Galileo Region
<h1>PIA00579: Ganymede Uruk Sulcus High Resolution Mosaic Shown in Context</h1><div class="PIA00579" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">A mosaic of four Galileo high-resolution images of the Uruk Sulcus region of Jupiter's moon Ganymede (Latitude 11 N, Longitude: 170 W) is shown within the context of an image of the region taken by Voyager 2 in 1979, which in turn is shown within the context of a full-disk image of Ganymede. North is to the top of the picture, and the sun illuminates the surface from the lower left, nearly overhead. The area shown is about 120 by 110 kilometers (75 by 68 miles) in extent and the smallest features that can be discerned are 74 meters (243 feet) in size in the Galileo images and 1.3 kilometers (0.8 miles) in the Voyager data. The higher resolution Galileo images unveil the details of parallel ridges and troughs that are principal features in the brighter regions of Ganymede. High photometric activity (large light contrast at high spatial frequencies) of this ice-rich surface was such that the Galileo camera's hardware data compressor was pushed into truncating lines. The north-south running gap between the left and right halves of the mosaic is a result of line truncation from the normal 800 samples per line to about 540. The images were taken on 27 June, 1996 Universal Time at a range of 7,448 kilometers (4,628 miles) through the clear filter of the Galileo spacecraft's imaging system.<p>Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment.<p>The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00579" onclick="window.open(this.href); return false;" title="Voir l'image PIA00579: Ganymede Uruk Sulcus High Resolution Mosaic Shown in Context sur le site de la NASA">Voir l'image PIA00579: Ganymede Uruk Sulcus High Resolution Mosaic Shown in Context sur le site de la NASA.</a></div>
PIA00579: Ganymede Uruk Sulcus High Resolution Mosaic Shown in Context
<h1>PIA00580: Ganymede Galileo Regio High Resolution Mosaic Shown in Context</h1><div class="PIA00580" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Ancient impact craters shown in this image of Jupiter's moon Ganymede taken by NASA's Galileo spacecraft testify to the great age of the terrain, dating back several billion years. At the margin at the left, half of a 19-kilometer-diameter (12-mile) crater is visible. The dark and bright lines running from lower right to upper left and from top to bottom are deep furrows in the ancient crust of dirty water ice. The origin of the dark material is unknown, but it may be accumulated dark fragments from many meteorites that hit Ganymede. In this view, north is to the top, and the sun illuminates the surface from the lower left about 58 degrees above the horizon. The area shown is part of Ganymede's Galileo Regio region at latitude 18 degrees north, longitude 147 degrees west; it is about 46 by 64 kilometers (29 by 38 miles) in extent. Resolution is about 80 meters (262 feet) per pixel. The image was taken June 27 at a range of 7.563 kilometers (4,700 miles).<p>The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00580" onclick="window.open(this.href); return false;" title="Voir l'image PIA00580: Ganymede Galileo Regio High Resolution Mosaic Shown in Context sur le site de la NASA">Voir l'image PIA00580: Ganymede Galileo Regio High Resolution Mosaic Shown in Context sur le site de la NASA.</a></div>
PIA00580: Ganymede Galileo Regio High Resolution Mosaic Shown in Context
<h1>PIA00705: Detail of Ganymede's Uruk Sulcus Region as Viewed by Galileo and Voyager</h1><div class="PIA00705" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">View of the region of Ganymede's Uruk Sulcus placed on a lower resolution Voyager view taken 17 years earlier. North is to the top of the picture and the sun illuminates the surface from almost overhead in the Galileo view. The finest details that can be discerned in the Galileo picture are about 80 meters across. The four boxes outlined in white show the extent of Galileo's initial look at this area. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00705" onclick="window.open(this.href); return false;" title="Voir l'image PIA00705: Detail of Ganymede's Uruk Sulcus Region as Viewed by Galileo and Voyager sur le site de la NASA">Voir l'image PIA00705: Detail of Ganymede's Uruk Sulcus Region as Viewed by Galileo and Voyager sur le site de la NASA.</a></div>
PIA00705: Detail of Ganymede's Uruk Sulcus Region as Viewed by Galileo and Voyager
<h1>PIA00706: Ganymede Global</h1><div class="PIA00706" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">View of Ganymede from the Galileo spacecraft during its first encounter with the Satellite. North is to the top of the picture and the sun illuminates the surface from the right. The finest details that can be discerned in this picture are about 6.7 kilometers across. The Universal Time is 8:45:09 UT on June 26, 1996. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00706" onclick="window.open(this.href); return false;" title="Voir l'image PIA00706: Ganymede Global sur le site de la NASA">Voir l'image PIA00706: Ganymede Global sur le site de la NASA.</a></div>
PIA00706: Ganymede Global
<h1>PIA00707: Fine Details of the Icy Surface of Ganymede</h1><div class="PIA00707" lang="en" style="width:580px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Dramatic view of fine details in ice hills and valleys in an unnamed region on Jupiter's moon Ganymede. North is to the top of the picture and the sun illuminates the surface from the left. The finest details that can be discerned in this picture are only 11 meters across (similar to the size of an average house) some 2000 times better than previous images of this region. The bright areas in the left hand version are the sides of hills facing the sun; the dark areas are shadows. In the right hand version the processing has been changed to bring out details in the shadowed regions that are illuminated by the bright hillsides. The brightness of some of the hillsides is so high that the picture elements "spill over" down the columns of the picture. The image was taken on June 28, 1996 from a distance of about 1000 kilometers. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00707" onclick="window.open(this.href); return false;" title="Voir l'image PIA00707: Fine Details of the Icy Surface of Ganymede sur le site de la NASA">Voir l'image PIA00707: Fine Details of the Icy Surface of Ganymede sur le site de la NASA.</a></div>
PIA00707: Fine Details of the Icy Surface of Ganymede