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

<h1>PIA00716: Ganymede Color Global</h1><div class="PIA00716" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Natural color 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 dark areas are the older, more heavily cratered regions and the light areas are younger, tectonically deformed regions. The brownish-gray color is due to mixtures of rocky materials and ice. Bright spots are geologically recent impact craters and their ejecta. The finest details that can be discerned in this picture are about 13.4 kilometers across. The images which combine for this color image were taken beginning at Universal Time 8:46:04 UT on June 26, 1996.<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 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/PIA00716" onclick="window.open(this.href); return false;" title="Voir l'image PIA00716: Ganymede Color Global sur le site de la NASA">Voir l'image PIA00716: Ganymede Color Global sur le site de la NASA.</a></div>
PIA00716: Ganymede Color Global
<h1>PIA00722: Galileo Resolutions: Ganymede and the San Francisco Bay Area</h1><div class="PIA00722" lang="en" style="width:523px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">These frames 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 spacecraft's many orbits allow numerous close flyby's of Jupiter and its moons. The top left frame shows the best resolution (1.3 kilometers per picture element or pixel) data of the Uruk Sulcus region on Jupiter's moon Ganymede which was available after the 1979 flyby of the Voyager 2 spacecraft. The top right frame shows the same area as captured by Galileo during its closer flyby of Ganymede on June 27, 1996 at a range of 7,448 kilometers (4.628 miles). For comparison, the bottom frames show images of the San Francisco Bay area trimmed to the size of the Ganymede images and adjusted to similar resolutions.<p>The Galileo image of Uruk Sulcus has a resolution of about 74 meters per pixel. The area shown is about 35 by 55 kilometers (25 by 34 miles). North is to the top, and the sun illuminates the surface from the lower left. The image taken by the Solid State Imaging (CCD) system reveals details of the structure and shape of the ridges which permit scientists to determine their origin and their relation to other terrains. These new views are helping to unravel the complex history of this planet-sized moon.<p>The left SF Bay area image is from an image obtained by an Advanced Very High Resolution Radiometer aboard an NOAA satellite. The right SF Bay area image is from a LandSat Thematic Mapper. Golden Gate Park is clearly visible as a narrow dark rectangle towards the middle of this image. Both images were trimmed and adjusted to resolutions similar to the Ganymede images.<p>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 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/PIA00722" onclick="window.open(this.href); return false;" title="Voir l'image PIA00722: Galileo Resolutions: Ganymede and the San Francisco Bay Area sur le site de la NASA">Voir l'image PIA00722: Galileo Resolutions: Ganymede and the San Francisco Bay Area sur le site de la NASA.</a></div>
PIA00722: Galileo Resolutions: Ganymede and the San Francisco Bay Area
<h1>PIA00878: NIMS Observes Melkart Crater on Ganymede</h1><div class="PIA00878" lang="en" style="width:445px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The top figure is an image of the crater Melkart on Ganymede, at a wavelength of 0.85 microns, taken by the Near Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft, The crater is illuminated by the Sun from the left. The finest detail that can be seen is approximately 30 km in size. What is most obvious, and of great interest, are the two concentric ring structures and the central dome. The walls of these rings are in shadow on the left, and are in sunlight on the right. To understand how these rings and central dome are thought to form, consider a pebble dropped into a pond. Ripples spread out from the center, oscillating up and down. The rings and dome forming Melkart are a snapshot of these ripples in the ice of Ganymede, possibly caused by the impact of a comet or asteroid. Similar features on the Moon are only associated with much larger craters as the stronger Moon rock behaves this way only with large impacts. NIMS can obtain images at many different wavelengths from 0.7 to 5.2 microns.<p>The spectrum shows the amount of reflected light as a function of wavelength from the crater floor of Melkart. Several distinct absorption features, caused by water ice, are evident at 1.5 and 2.0 microns. Beyond 3.0 microns the intensity increases again as the longer wavelengths are more sensitive to Ganymede's thermal radiation. The shape of the absorption features suggest that the ice is mixed with hydrated minerals. These relatively dark minerals probably cause the variations in ice brightness seen at visible wavelengths.<p>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 URL http://www.jpl.nasa.gov/ galileo.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00878" onclick="window.open(this.href); return false;" title="Voir l'image PIA00878: NIMS Observes Melkart Crater on Ganymede sur le site de la NASA">Voir l'image PIA00878: NIMS Observes Melkart Crater on Ganymede sur le site de la NASA.</a></div>
PIA00878: NIMS Observes Melkart Crater on Ganymede
<h1>PIA01056: Ganymede Groove Lanes</h1><div class="PIA01056" lang="en" style="width:321px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">An ancient dark terrain surface is cut by orthogonal sets of fractures on Jupiter's moon Ganymede. Subdued pits visible on unbroken blocks are the remnants of impact craters which have degraded with time. Across the top of the image, a line of these subdued pits may have been a chain of craters which are now cut apart by the northwest to southeast trending fractures. North is to the top. Younger craters appear as bright circles. The fractures in this image range from less than 100 meters (328 feet) to over a kilometer (0.62 miles) in width. They display bright walls where cleaner ice may be exposed, and deposits of dark material fill their floors. This 27 by 22 kilometer (17 by 14 mile) image of northern Marius Regio was obtained on September 6, 1996 by NASA's Galileo spacecraft at a resolution of 85 meters (278 feet) per picture element (pixel).<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 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/PIA01056" onclick="window.open(this.href); return false;" title="Voir l'image PIA01056: Ganymede Groove Lanes sur le site de la NASA">Voir l'image PIA01056: Ganymede Groove Lanes sur le site de la NASA.</a></div>
PIA01056: Ganymede Groove Lanes
<h1>PIA01057: A Polar Crater on Ganymede</h1><div class="PIA01057" lang="en" style="width:519px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This circular 36 kilometer (22 mile) diameter impact crater near the north pole of Jupiter's moon Ganymede has a floor that is partially brightened. On September 6, 1996, NASA's Galileo spacecraft obtained images of an 18 kilometer (11 miles) wide swath through this area. The Galileo data, acquired at a resolution of 46 meters (151 feet) pixel (picture element), is shown overlain on data obtained by NASA's Voyager spacecraft in 1979. In Voyager data the crater was thought to be flooded by icy volcanism, but in Galileo data it is seen to be brightened by frost deposition. The Voyager data, taken at a resolution of 1.3 kilometers (0.8 miles) per pixel, shows a circular feature with a bright deposit on the northern half of its floor. North is toward the top of the picture. Illumination in the image is from the southeast, and frost appears to be collecting on north facing slopes of ridges and crater rims. Fractures cross the floor of the large crater, and the northeastern rim displays two large blocks of ice which have collapsed off the side of the steep crater wall. The Galileo images were taken by the Solid State Imaging (CCD) system at a range of about 2243 kilometers (1391 miles) from the surface of Ganymede.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 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/PIA01057" onclick="window.open(this.href); return false;" title="Voir l'image PIA01057: A Polar Crater on Ganymede sur le site de la NASA">Voir l'image PIA01057: A Polar Crater on Ganymede sur le site de la NASA.</a></div>
PIA01057: A Polar Crater on Ganymede
<h1>PIA01058: Bright and Dark Slopes on Ganymede</h1><div class="PIA01058" lang="en" style="width:411px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Ridges on the edge of Ganymede's north polar cap show bright east-facing slopes and dark west-facing slopes with troughs of darker material below the larger ridges. North is to the top. The bright slopes may be due to grain size differences, differences in composition between the original surface and the underlying material, frost deposition, or illumination effects. The large 2.4 kilometer (1.5 mile) diameter crater in this image shows frost deposits located on the north-facing rim slope, away from the sun. A smaller 675 meter (2200 foot) diameter crater in the center of the image is surrounded by a bright deposit which may be ejecta from the impact. Ejecta deposits such as this are uncommon for small craters on Ganymede. This image measures 18 by 19 kilometers (11 by 12 miles) and has a resolution of 45 meters (148 feet) per pixel. NASA's Galileo spacecraft obtained this image on September 6, 1996 during its second orbit around Jupiter.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 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/PIA01058" onclick="window.open(this.href); return false;" title="Voir l'image PIA01058: Bright and Dark Slopes on Ganymede sur le site de la NASA">Voir l'image PIA01058: Bright and Dark Slopes on Ganymede sur le site de la NASA.</a></div>
PIA01058: Bright and Dark Slopes on Ganymede
<h1>PIA01059: Grooves and Craters on Ganymede</h1><div class="PIA01059" lang="en" style="width:245px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Grooved terrain in this area of Nippur Sulcus on Jupiter's moon Ganymede is composed of ridges and troughs spaced 1 to 2 kilometers (0.6 to 1.2 miles) apart. North is to the top. A few broad (4 to 5 kilometer (2.5 to 3.1 mile) wide) ridges such as those in the northeast and southwest corners have smaller ridges on top of them. A 12 kilometer (7 mile) diameter impact crater is superimposed on these ridges. A dark ring at the base of the crater walls may be due to a collection of dark material at the base of the steep slopes. The image is 49 by 41 kilometers (30 by 25 miles) with a resolution of 200 meters (656 feet) per picture element (pixel). This image was obtained on September 6, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 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/PIA01059" onclick="window.open(this.href); return false;" title="Voir l'image PIA01059: Grooves and Craters on Ganymede sur le site de la NASA">Voir l'image PIA01059: Grooves and Craters on Ganymede sur le site de la NASA.</a></div>
PIA01059: Grooves and Craters on Ganymede
<h1>PIA01060: Palimpsest secondary craters on Ganymede</h1><div class="PIA01060" lang="en" style="width:430px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This region of grooved terrain on Jupiter's moon Ganymede has been partially covered by ejecta from an ancient impact structure known as a palimpsest. Palimpsests are circular, bright, low relief features formed long ago by impacts into Ganymede's surface when this surface behaved differently than it does today.<p>This composite of three images was obtained by the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on 6 September, 1996 (Universal Time) at a resolution of 88 meters per picture element (pixel). A lower resolution Voyager image of the same area is in the background. North is to the top. Part of this 350 kilometer (km) diameter unnamed palimpsest is visible as only a slight brightening of the surface in the upper left half of this image. The edge of the palimpsest crosses this picture from lower left to upper right.<p>Secondary craters 5 to 7 km across produced during the palimpsest-forming impact are visible outside the palimpsest, in the lower right half of the picture. Inside the palimpsest, short northwest-southeast trending chains of similar sized craters can be discerned but with much more difficulty, as these craters inside the palimpsest are buried by ejecta. Similarly, the southwest-northeast trending grooves seen clearly outside the palimpsest can be seen with difficulty for a short distance within the palimpsest, where they have been covered by ejecta. This shows that the edge of the palimpsest is the edge of an ejecta blanket.<p>Lower resolution images from the NASA's Voyager mission in 1979 revealed the palimpsests on Ganymede, but did not provide enough detail to allow them to be understood completely. Galileo images of this and several other palimpsests on Ganymede are used in conjunction with the Voyager images to provide a more complete understanding of just how these structures formed.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 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/PIA01060" onclick="window.open(this.href); return false;" title="Voir l'image PIA01060: Palimpsest secondary craters on Ganymede sur le site de la NASA">Voir l'image PIA01060: Palimpsest secondary craters on Ganymede sur le site de la NASA.</a></div>
PIA01060: Palimpsest secondary craters on Ganymede
<h1>PIA01061: Secondary Craters on Ganymede</h1><div class="PIA01061" lang="en" style="width:382px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Two large, ancient impact craters, known as palimpsests, have modified this area of dark terrain on Jupiter's moon Ganymede. In lower resolution images from the Voyager mission in 1979, it was observed that the diffuse edge of a large, circular bright feature cut through this area. This image was obtained by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft, on September 6, 1996, at a higher resolution of 190 meters (623 feet) per picture element (pixel). North is to the top. The diffuse margin of this palimpsest is noticeable only as a gradual increase in the area covered by bright hummocks toward the western edge of the image. A more recent palimpsest-forming impact to the south has peppered this area with chains and clusters of secondary craters ranging from 5.7 to 1.2 kilometers (3.5 to 0.7 miles) in diameter. The image covers an area of 73 by 65 kilometers (45 by 40 miles).<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 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/PIA01061" onclick="window.open(this.href); return false;" title="Voir l'image PIA01061: Secondary Craters on Ganymede sur le site de la NASA">Voir l'image PIA01061: Secondary Craters on Ganymede sur le site de la NASA.</a></div>
PIA01061: Secondary Craters on Ganymede
<h1>PIA01062: Fractures in Transitional Terrain on Ganymede</h1><div class="PIA01062" lang="en" style="width:357px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This area of dark terrain on Jupiter's moon Ganymede lies near a transitional area between dark and bright terrain. The dark surface is cut by a pervasive network of fractures, which range in width from the limit of resolution up to 2.2 kilometers (1.4 miles). Bright material is exposed in the walls of the chasms, and dark material fills the troughs. The impurities which darken the ice on the surface of dark terrain may be only a thin veneer over a brighter ice crust. Over time, these materials may be shed down steep slopes, where they collect in low areas. The image is 68 by 54 kilometers (42 by 33 miles), and has a resolution of 190 meters (623 feet) per picture element (pixel). North is to the top. This image was obtained on September 6, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 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/PIA01062" onclick="window.open(this.href); return false;" title="Voir l'image PIA01062: Fractures in Transitional Terrain on Ganymede sur le site de la NASA">Voir l'image PIA01062: Fractures in Transitional Terrain on Ganymede sur le site de la NASA.</a></div>
PIA01062: Fractures in Transitional Terrain on Ganymede
<h1>PIA01086: Grooved Terrain in Nippur Sulcus on Ganymede</h1><div class="PIA01086" lang="en" style="width:648px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Complex sets of ridges and grooves are visible in this image of the Nippur Sulcus region on Jupiter's largest moon Ganymede. NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. The Nippur Sulcus region is an example of Bright Terrain on Ganymede which is typified by multiple sets of ridges and grooves. The intersections of these sets reveal complex age relationships. North is to the top of the picture and the sun illuminates the surface from the southeast (lower right). In this image a younger sinuous northwest-southeast trending groove set cuts through and apparently destroys the older east-west trending features on the right of the image, allowing scientists to determine the sequence of events that led to the region's formation. The area contains many impact craters. The large crater in the bottom of the image is about 12 kilometers (8 miles) in diameter.<p>The image, centered at 51 degrees latitude and 204 degrees longitude, covers an area approximately 79 kilometers (50 miles) by 57 kilometers (36 miles) across. The resolution is 93 meters (330 feet) per picture element. The images were taken on September 6, 1996 at a range of 9,971 kilometers (6,232 miles) by the solid state imaging (CCD) system on NASA's Galileo spacecraft.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 URL http://galileo.jpl.nasa.gov.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01086" onclick="window.open(this.href); return false;" title="Voir l'image PIA01086: Grooved Terrain in Nippur Sulcus on Ganymede sur le site de la NASA">Voir l'image PIA01086: Grooved Terrain in Nippur Sulcus on Ganymede sur le site de la NASA.</a></div>
PIA01086: Grooved Terrain in Nippur Sulcus on Ganymede
<h1>PIA01087: Geological mysteries on Ganymede</h1><div class="PIA01087" lang="en" style="width:648px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This image shows some unusual features on the surface of Jupiter's moon, Ganymede. NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. The region is located at 31 degrees latitude, 186 degrees longitude in the north of Marius Regio, a region of ancient dark terrain, and is near the border of a large swathe of younger, heavily tectonised bright terrain known as Nippur Sulcus. Situated in the transitional region between these two terrain types, the area shown here contains many complex tectonic structures, and small fractures can be seen crisscrossing the image. North is to the top-left of the picture, and the sun illuminates the surface from the southeast. This image is centered on an unusual semicircular structure about 33 kilometers (20 miles) across. A 38 kilometer (24 miles) long, remarkably linear feature cuts across its northern extent, and a wide east-west fault system marks its southern boundary. The origin of these features is the subject of much debate among scientists analyzing the data. Was the arcuate structure part of a larger feature? Is the straight lineament the result of internal or external processes? Scientists continue to study this data in order to understand the surface processes occurring on this complex satellite.<p>The image covers an area approximately 80 kilometers (50 miles) by 52 kilometers (32 miles) across. The resolution is 189 meters (630 feet) per picture element. The images were taken on September 6, 1996 at a range of 9,971 kilometers (6,232 miles) by the solid state imaging (CCD) system on NASA's Galileo spacecraft.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 URL http://galileo.jpl.nasa.gov.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01087" onclick="window.open(this.href); return false;" title="Voir l'image PIA01087: Geological mysteries on Ganymede sur le site de la NASA">Voir l'image PIA01087: Geological mysteries on Ganymede sur le site de la NASA.</a></div>
PIA01087: Geological mysteries on Ganymede
<h1>PIA01088: Nergal Crater on Ganymede</h1><div class="PIA01088" lang="en" style="width:648px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Two impact craters surrounded by an unusual ejecta blanket dominate this high resolution image of the surface of Jupiter's moon, Ganymede. NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. North is to the top of the picture and the sun illuminates the surface from the southeast. Nergal, the larger crater, is about eight kilometers (five miles) in diameter, while the smaller (unnamed) crater to its west is three kilometers (1.8 miles) across. The craters are situated in a region of bright grooved terrain named Byblus Sulcus, located in the northern part of Marius Regio at 39 degrees latitude and 201 degrees longitude. The distinctive ejecta blanket that surrounds them is darker nearer the craters and brighter further away. The inner region of the ejecta is characterized by a lobate appearance indicative of the flow of a liquid (or slushy) substance over the surface. The flow was probably icy surface material melted by the energy released during the impact that formed the crater.<p>The picture covers an area about 48 kilometers (30 miles) by 34 kilometers (21 miles) across at a resolution of 86 meters (287 feet) per picture element. The image was taken on September 6, 1996 by the solid state imaging (CCD) system on NASA's Galileo spacecraft.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 URL http://galileo.jpl.nasa.gov.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01088" onclick="window.open(this.href); return false;" title="Voir l'image PIA01088: Nergal Crater on Ganymede sur le site de la NASA">Voir l'image PIA01088: Nergal Crater on Ganymede sur le site de la NASA.</a></div>
PIA01088: Nergal Crater on Ganymede
<h1>PIA01089: Fractured Craters on Ganymede</h1><div class="PIA01089" lang="en" style="width:400px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Two highly fractured craters are visible in this high resolution image of Jupiter's moon, Ganymede. NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. North is to the top of the picture and the sun illuminates the surface from the southeast. The two craters in the center of the image lie in the ancient dark terrain of Marius Regio, at 40 degrees latitude and 201 degrees longitude, at the border of a region of bright grooved terrain known as Byblus Sulcus (the eastern portion of which is visible on the left of this image). Pervasive fracturing has occurred in this area that has completely disrupted these craters and destroyed their southern and western walls. Such intense fracturing has occurred over much of Ganymede's surface and has commonly destroyed older features. The image covers an area approximately 26 kilometers (16 miles) by 18 kilometers (11 miles) across at a resolution of 86 meters (287 feet) per picture element. The image was taken on September 6, 1996 by the solid state imaging (CCD) system on NASA's Galileo spacecraft.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 URL http://galileo.jpl.nasa.gov.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01089" onclick="window.open(this.href); return false;" title="Voir l'image PIA01089: Fractured Craters on Ganymede sur le site de la NASA">Voir l'image PIA01089: Fractured Craters on Ganymede sur le site de la NASA.</a></div>
PIA01089: Fractured Craters on Ganymede
<h1>PIA01090: Khensu Crater on Ganymede</h1><div class="PIA01090" lang="en" style="width:620px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The dark-floored crater, Khensu, is the target of this image of Ganymede. The solid state imaging camera on NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. Khensu is located at 2 degrees latitude and 153 degrees longitude in a region of bright terrain known as Uruk Sulcus, and is about 13 kilometers (8 miles) in diameter. Like some other craters on Ganymede, it possesses an unusually dark floor and a bright ejecta blanket. The dark component may be residual material from the impactor that formed the crater. Another possibility is that the impactor may have punched through the bright surface to reveal a dark layer beneath.<p>Another large crater named El is partly visible in the top-right corner of the image. This crater is 54 kilometers (34 miles) in diameter and has a small "pit" in its center. Craters with such a "central pit" are common across Ganymede and are especially intriguing since they may reveal secrets about the structure of the satellite's shallow subsurface.<p>North is to the top-left of the picture and the sun illuminates the surface from nearly overhead. The image covers an area about 100 kilometers (62 miles) by 86 kilometers (54 miles) across at a resolution of 111 meters (370 feet) per picture element. The image was taken on September 6, 1996 by the solid state imaging (CCD) system on NASA's Galileo spacecraft.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 URL http://galileo.jpl.nasa.gov.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01090" onclick="window.open(this.href); return false;" title="Voir l'image PIA01090: Khensu Crater on Ganymede sur le site de la NASA">Voir l'image PIA01090: Khensu Crater on Ganymede sur le site de la NASA.</a></div>
PIA01090: Khensu Crater on Ganymede
<h1>PIA01091: Complex Tectonism on Ganymede</h1><div class="PIA01091" lang="en" style="width:720px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Complex tectonism is evident in these images of Ganymede's surface. The solid state imaging camera on NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. The 80 kilometer (50 mile) wide lens-shaped feature in the center of the image is located at 32 degrees latitude and 188 degrees longitude along the border of a region of ancient dark terrain known as Marius Regio, and is near an area of younger bright terrain named Nippur Sulcus. The tectonism that created the structures in the bright terrain nearby has strongly affected the local dark terrain to form unusual structures such as the one shown here. The lens-like appearance of this feature is probably due to shearing of the surface, where areas have slid past each other and also rotated slightly. Note that in several places in these images, especially around the border of the lens-shaped feature, bright ridges appear to turn into dark grooves. Analysis of the geologic structures in areas like this are helping scientists to understand the complex tectonic history of Ganymede.<p>North is to the top-left of the image, and the sun illuminates the surface from the southeast. The image covers an area about 63 kilometers (39 miles) by 120 kilometers (75 miles) across at a resolution of 188 meters (627 feet) per picture element. The images were taken on September 6, 1996 at a range of 18,522 kilometers (11,576 miles) by the solid state imaging (CCD) system on NASA's Galileo spacecraft.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<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 URL http://galileo.jpl.nasa.gov.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01091" onclick="window.open(this.href); return false;" title="Voir l'image PIA01091: Complex Tectonism on Ganymede sur le site de la NASA">Voir l'image PIA01091: Complex Tectonism on Ganymede sur le site de la NASA.</a></div>
PIA01091: Complex Tectonism on Ganymede
<h1>PIA01515: Bright Ray Craters in Ganymede's Northern Hemisphere</h1><div class="PIA01515" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">GANYMEDE COLOR PHOTOS: This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The images show detail on the surface with a resolution of four and a half km. This picture is of a region in the northern hemisphere near the terminator. It shows a variety of impact structures, including both razed and unrazed craters, and the odd, groove-like structures discovered by Voyager in the lighter regions. The most striking features are the bright ray craters which have a distinctly 'bluer' color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggests that here, too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems of the crater in the southern part of this picture, which has rays at least 300-500 kilometers long, down to craters which have only faint remnants of bright ejects patterns (such as several of the craters in the southern half of PIA01516; P21262). This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably 'gardening' by micrometeoroid 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/PIA01515" onclick="window.open(this.href); return false;" title="Voir l'image PIA01515: Bright Ray Craters in Ganymede's Northern Hemisphere sur le site de la NASA">Voir l'image PIA01515: Bright Ray Craters in Ganymede's Northern Hemisphere sur le site de la NASA.</a></div>
PIA01515: Bright Ray Craters in Ganymede's Northern Hemisphere
<h1>PIA01516: Cratering and Grooved Terrain on Ganymede</h1><div class="PIA01516" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The image shows detail on the surface with a resolution of four and a half km. This picture is just south of PIA001515 (P21161) and shows more craters. It also shows the two distinctive types of terrain found by Voyager, the darker ungrooved regions and the lighter areas which show the grooves or fractures in abundance. The most striking features are the bright ray craters which havE a distinctly "bluer" color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggests that here too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems of the crater in the northern part of this picture, which has rays at least 300-500 kilometers long, down to craters which have only faint remnants of bright ejecta patterns. This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably "gardening" by micrometeoroid 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/PIA01516" onclick="window.open(this.href); return false;" title="Voir l'image PIA01516: Cratering and Grooved Terrain on Ganymede sur le site de la NASA">Voir l'image PIA01516: Cratering and Grooved Terrain on Ganymede sur le site de la NASA.</a></div>
PIA01516: Cratering and Grooved Terrain on Ganymede
<h1>PIA01517: Ganymede's Equatorial Region</h1><div class="PIA01517" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">GANYMEDE COLOR PHOTOS: This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The images show detail on the surface with a resolution of four and a half km. This picture is south of PIA01516 (P21262) near the equator of Ganymede, and has relatively subdued colors in the visible part of the spectrum (later, scientists will analyze Voyager pictures taken in UV). The most striking features are the bright ray craters which have a distinctly "bluer" color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggest that here, too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems, down to craters which have only faint remnants of bright ejecta patterns. This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably "gardening" by micrometeoroid 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/PIA01517" onclick="window.open(this.href); return false;" title="Voir l'image PIA01517: Ganymede's Equatorial Region sur le site de la NASA">Voir l'image PIA01517: Ganymede's Equatorial Region sur le site de la NASA.</a></div>
PIA01517: Ganymede's Equatorial Region
<h1>PIA01520: Ganymede's Varied Terrain</h1><div class="PIA01520" lang="en" style="width:780px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Voyager 2 took this picture of Ganymede as the spacecraft was nearing its encounter with the ice giant. It was taken from a range of 312,000 kilometers (195,000 miles), and it shows features down to about 5 to 6 kilometers across. Clear examples of several of the different types of terras in common on Ganymede s surface are visible (right).. The boundary of the largest region of dark ancient terrain on Ganymede can be seen to the east (right), revealing some of the light linear features which may be all that remains of a large ancient impact structure similar to the large ring structure on Callisto. The broad light regions running through the image are the typical grooved structures seen within most of the light regions on Ganymede. To the lower left is another example of what might be evidence of large scale lateral motion in Ganymede's crust. The band of grooved terrain (about 100 kilometers wide) in this region appears to be offset by 50 kilometers or more on the left hand edge by a linear feature perpendicular to it. A feature similar to this one was previously discovered by Voyager 1. These are the first clear examples of strike-slip style faulting on any planet other than Earth. Many examples of craters of all ages can be seen in this image, ranging from fresh, bright ray craters to large, subdued circular markings thought to be the "scars" of large ancient impacts that have been flattened by glacier-like flows.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01520" onclick="window.open(this.href); return false;" title="Voir l'image PIA01520: Ganymede's Varied Terrain sur le site de la NASA">Voir l'image PIA01520: Ganymede's Varied Terrain sur le site de la NASA.</a></div>
PIA01520: Ganymede's Varied Terrain
<h1>PIA01606: Completing a Global Map of Ganymede</h1><div class="PIA01606" lang="en" style="width:670px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>When NASA's two Voyager spacecraft passed through the Jupiter system in 1979, they captured many high resolution images of the Galilean satellites, but these encounters left some regions of these four largest Jovian moons poorly seen. One of the primary objectives of NASA's Galileo mission was to acquire images of areas that Voyager could not see. This is one such image, showing part of the leading hemisphere of Ganymede. Many fragmented regions of dark terrain split by lanes of bright grooved terrain cover the surface. Several bright young craters can be seen, including a linear chain of craters near the center of the image which may have resulted from the impact of a fragmented comet, similar to comet Shoemaker-Levy/9 which hit Jupiter in 1994.</p><p>North is to the top of the picture and the sun illuminates the surface from the left. The mosaic, centered at 0 degrees latitude and 285 degrees longitude, covers an area approximately 2800 by 5100 kilometers. The resolution is 3.6 kilometers per picture element. The images were taken on February 21, 1997 at 20 hours, 25 minutes, 29 seconds Universal Time at a range of 34,386 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://galileo.jpl.nasa.gov">http:// galileo.jpl.nasa.gov</a>. 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/PIA01606" onclick="window.open(this.href); return false;" title="Voir l'image PIA01606: Completing a Global Map of Ganymede sur le site de la NASA">Voir l'image PIA01606: Completing a Global Map of Ganymede sur le site de la NASA.</a></div>
PIA01606: Completing a Global Map of Ganymede
<h1>PIA01607: Dark-floored Impact Craters on Ganymede</h1><div class="PIA01607" lang="en" style="width:392px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>View of two impact craters that are superimposed on Memphis Facula, a large bright circular feature in the otherwise generally dark terrain in Galileo Regio on Jupiter's moon, Ganymede. These are thought to be impact craters because they share many of the features of such structures on other planets, including steep walls, flat floors, and central mountain peaks. Bright icy material is exposed on the walls, rims and peaks of these features and darker material can be seen covering the floors and streaming down the inner walls of the craters. The dark material may have been concentrated on the crater floors during the impact events. A dark line near the crater rim may be exposures of layered bedrock which has been uplifted. These craters have been degraded to the degree that their ejecta and surrounding secondary crater fields are no longer visible. The crater on the left (Chrysor) is about 6 kilometers (km) in diameter and the larger one on the right (Aleyn) is about 12 km wide. Smaller craters are seen as bright circles on the crater floors and in the surrounding areas. The density of these superposed impact features allows scientists to estimate the age of the surface and the age of the craters, thought to be many hundreds of millions of years old. Memphis Facula, a large 350 km diameter bright feature on which the craters are situated, appears to have formed from the excavation of bright water ice material during an ancient, large impact event.</p><p>North is to the top left of the picture and the sun illuminates the surface from the bottom. The image, centered at 15 degrees latitude and 134 degrees longitude, covers an area approximately 23 by 23 kilometers. The resolution is 59 meters per picture element. The image was taken on June 27, 1996 at 6 hours, 21 minutes, 19 seconds Universal Time at a range of 2849 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://galileo.jpl.nasa.gov/galileo/sepo"><a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.</a><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01607" onclick="window.open(this.href); return false;" title="Voir l'image PIA01607: Dark-floored Impact Craters on Ganymede sur le site de la NASA">Voir l'image PIA01607: Dark-floored Impact Craters on Ganymede sur le site de la NASA.</a></div>
PIA01607: Dark-floored Impact Craters on Ganymede
<h1>PIA01608: High Latitude "Bright" and "Dark" Terrains on Ganymede</h1><div class="PIA01608" lang="en" style="width:707px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>During Galileo's second orbit, a series of images were obtained within the northern polar cap of Jupiter's moon, Ganymede, across a north-south trending boundary between the grooved terrain of Philae Sulcus and the dark terrain of Galileo Regio. The blurry appearing background of this scene is the best Voyager image of the area, at a resolution of about 1.4 kilometers per picture element. The Voyager data shows that the grooved terrain of Philae Sulcus to the west (left) is bright, and the older terrain of Galileo Regio to the east (right) is dark; however, this brightness difference is not at all apparent in the high resolution Galileo images. Instead, bright and dark patches occur in both Philae Sulcus and in Galileo Regio. <a href="/catalog/PIA00496">The bright patches occur mostly on the north and east facing slopes of craters and ridges</a>, which are expected to be colder, and therefore to collect frost in this high latitude region. The principal way that Ganymede's terrain types can be distinguished in the high resolution Galileo images is by their texture: the "bright" grooved terrain shows north-south trending ridges and grooves, and the ancient "dark" terrain shows a rolling appearance and is more heavily cratered.</p><p>North is to the top of the picture and the sun illuminates the surface from the lower right. The image, centered at 63 degrees latitude and 168 degrees longitude, covers an area approximately 94 by 64 kilometers. The finest details that can discerned in this picture are about 92 meters across. The images were taken on September 6, 1996 beginning at 18 hours, 52 minutes, 46 seconds Universal Time at a range of 2266 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://galileo.jpl.nasa.gov">http:// galileo.jpl.nasa.gov</a>. 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/PIA01608" onclick="window.open(this.href); return false;" title="Voir l'image PIA01608: High Latitude "Bright" and "Dark" Terrains on Ganymede sur le site de la NASA">Voir l'image PIA01608: High Latitude "Bright" and "Dark" Terrains on Ganymede sur le site de la NASA.</a></div>
PIA01608: High Latitude "Bright" and "Dark" Terrains on Ganymede
<h1>PIA01609: Fresh Impact Craters on Ganymede</h1><div class="PIA01609" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Oblique view of two fresh impact craters in bright grooved terrain near the north pole of Jupiter's moon, Ganymede. The craters postdate the grooved terrain since each is surrounded by swarms of smaller craters formed by material which was ejected out of the crater as it formed, and which subsequently reimpacted onto the surrounding surface. The crater to the north, Gula, which is 38 kilometers (km) in diameter, has a distinctive central peak, while the crater to the south, Achelous, (32 km in diameter) has an outer lobate ejecta deposit extending about a crater radius from the rim. Such images show the range of structural details of impact craters, and help in understanding the processes that form them.</p><p>North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at 62 degrees latitude and 12 degrees longitude, covers an area approximately 142 by 132 kilometers. The resolution is 175 meters per picture element. The images were taken on April 5, 1997 at 6 hours, 33 minutes, 37 seconds Universal Time at a range of 17,531 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://galileo.jpl.nasa.gov">http:// galileo.jpl.nasa.gov</a>. 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/PIA01609" onclick="window.open(this.href); return false;" title="Voir l'image PIA01609: Fresh Impact Craters on Ganymede sur le site de la NASA">Voir l'image PIA01609: Fresh Impact Craters on Ganymede sur le site de la NASA.</a></div>
PIA01609: Fresh Impact Craters on Ganymede
<h1>PIA01610: Anatomy of a Torn Comet</h1><div class="PIA01610" lang="en" style="width:392px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>View of a chain of craters named Enki Catena on Jupiter's moon, Ganymede. This chain of 13 craters probably formed by a comet which was pulled into pieces by Jupiter's gravity as it passed too close to the planet. Soon after this breakup, the 13 fragments crashed onto Ganymede in rapid succession. The Enki craters formed across the sharp boundary between areas of bright terrain and dark terrain, delimited by a thin trough running diagonally across the center of this image. The ejecta deposit surrounding the craters appears very bright on the bright terrain. Even though all the craters formed nearly simultaneously, it is difficult to discern any ejecta deposit on the dark terrain. This may be because the impacts excavated and mixed dark material into the ejecta and the resulting mix is not apparent against the dark background.</p><p>North is to the bottom of the picture and the sun illuminates the surface from the left. The image, centered at 39 degrees latitude and 13 degrees longitude, covers an area approximately 214 by 217 kilometers. The resolution is 545 meters per picture element. The image was taken on April 5, 1997 at 6 hours, 12 minutes, 22 seconds Universal Time at a range of 27282 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://galileo.jpl.nasa.gov">http:// galileo.jpl.nasa.gov</a>. 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/PIA01610" onclick="window.open(this.href); return false;" title="Voir l'image PIA01610: Anatomy of a Torn Comet sur le site de la NASA">Voir l'image PIA01610: Anatomy of a Torn Comet sur le site de la NASA.</a></div>
PIA01610: Anatomy of a Torn Comet
<h1>PIA01611: Kittu Dark Ray Crater</h1><div class="PIA01611" lang="en" style="width:692px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>View of the dark ray crater Kittu on Jupiter's moon, Ganymede. Kittu is seen in approximately true color, as imaged with the Galileo camera's violet, one micrometer, and near infrared filters. The crater shows a bright white central peak and rim, and dark brownish material surrounding it. Diffuse dark rays, sprinkled thinly atop surrounding grooved terrain, emanate from the impact site. The dark material dusted over the surface is probably part of a dark impactor (asteroid or comet) which was strewn across the surface upon impact. The impactor hit grooved terrain, and a straight segment of the crater's rim was created when a portion of the rim collapsed along the trend of an older fault.</p><p>North is to the bottom of the picture and the sun illuminates the surface from the left. The mosaic, centered at 0 degrees latitude and 335 degrees longitude, covers an area approximately 70 by 100 kilometers. The resolution in the color portion of this image is about 280 meters per picture element, while the resolution in the black and white portion is 145 meters per picture element. The images were taken beginning on April 5, 1997 from 6 hours, 39 minutes, 46 seconds Universal Time at a range of 14252 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://galileo.jpl.nasa.gov/galileo/sepo"><a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.</a><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01611" onclick="window.open(this.href); return false;" title="Voir l'image PIA01611: Kittu Dark Ray Crater sur le site de la NASA">Voir l'image PIA01611: Kittu Dark Ray Crater sur le site de la NASA.</a></div>
PIA01611: Kittu Dark Ray Crater
<h1>PIA01612: A Tumultuous Past for Ganymede's Dark Terrain</h1><div class="PIA01612" lang="en" style="width:615px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Dark terrain of Nicholson Regio on Jupiter's moon, Ganymede. On the left is a crater that has been torn apart by tectonic forces. A lane of ridges and grooves (probably extensional fault blocks) cuts through the crater and distorts its originally circular shape. Though such deformation is more typical of Ganymede's bright grooved terrain, this image demonstrates that extreme tectonic disruption has occurred in the satellite's dark terrain also. The pair of oblong craters on the right was formed by the impact of a gravitationally bound pair of asteroids or a split comet. The oblong shapes of the craters suggest that the impactors struck the surface at a shallow angle. Toward the top left, an old crater has been partially buried by dark ejecta tossed from another impact about 50 kilometers to the north of this image.</p><p>North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at 14 degrees south latitude and 352 degrees longitude, covers an area approximately 111 by 93 kilometers. The resolution is 180 meters per picture element. The image was taken on April 5, 1997 at 6 hours, 31 minutes, 44 seconds Universal Time at a range of 17,840 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. 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/PIA01612" onclick="window.open(this.href); return false;" title="Voir l'image PIA01612: A Tumultuous Past for Ganymede's Dark Terrain sur le site de la NASA">Voir l'image PIA01612: A Tumultuous Past for Ganymede's Dark Terrain sur le site de la NASA.</a></div>
PIA01612: A Tumultuous Past for Ganymede's Dark Terrain
<h1>PIA01613: Fractures in Nicholson Regio</h1><div class="PIA01613" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>View of Nicholson Regio on Jupiter's moon, Ganymede, showing heavily fractured dark terrain and a lane of smooth bright terrain. North is to the top of the picture. A smooth, linear plank-like strip of bright terrain cuts across the southeast (lower right) corner of the image. Just west (left) of this is a very heavily fractured lane of dark terrain, curving towards the south. This fractured lane looks bright in lower resolution Voyager images and may be transitional between the older, heavily fractured dark terrain, and younger, less densely cratered bright terrain. The many other fractures visible within the dark terrain probably result from extension in the area. Some of these fractures were focused around weaknesses created by older craters (such as the one just east of the image center).</p><p>The sun illuminates the surface from the right. The image, centered at 14 degrees south latitude and 352 degrees longitude, covers an area approximately 144 by 144 kilometers. The resolution is 180 meters per picture element. The image was taken on April 5, 1997 at 6 hours, 31 minutes, 35 seconds Universal Time at a range of 17,842 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://galileo.jpl.nasa.gov/galileo/sepo"><a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.</a><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01613" onclick="window.open(this.href); return false;" title="Voir l'image PIA01613: Fractures in Nicholson Regio sur le site de la NASA">Voir l'image PIA01613: Fractures in Nicholson Regio sur le site de la NASA.</a></div>
PIA01613: Fractures in Nicholson Regio
<h1>PIA01614: "Calderas" on Ganymede?</h1><div class="PIA01614" lang="en" style="width:531px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>NASA's Galileo imaging camera targeted an area in Sippar Sulcus on Jupiter's moon, Ganymede. Images obtained in 1979 by NASA's Voyager spacecraft showed that the area contained curvilinear and arcuate scarps or cliffs. These features appeared to be depressions which were candidate sources for some of the water ice volcanism thought to form the bright grooved terrain on Ganymede. The high resolution Galileo images seen here reveal that one of these structures contains a lobate, flow-like feature that is the best candidate yet seen for an icy volcanic lava flow on Ganymede. The prominent depression with scalloped walls and internal terraces is about 55 kilometers (km) in length and 17 to 20 km wide. On the floor of the inner depression is a lobate flow-like deposit 7 to 10 km wide with ridges that are curved outward (and apparently downslope) toward a cross-cutting lane of grooved terrain. The morphology of this structure suggests the possibility of volcanic eruptions creating a channel and flow, and cutting down into the surface.</p><p>North is to the bottom of the picture and the sun illuminates the surface from the left. The mosaic, centered at 31 degrees south latitude and 189 degrees longitude, covers an area approximately 91 by 62 kilometers. The resolution is 172 meters per picture element. The images were taken on May 7, 1997 at 15 hours, 18 minutes, 35 seconds Universal Time at a range of 17,489 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. 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/PIA01614" onclick="window.open(this.href); return false;" title="Voir l'image PIA01614: "Calderas" on Ganymede? sur le site de la NASA">Voir l'image PIA01614: "Calderas" on Ganymede? sur le site de la NASA.</a></div>
PIA01614: "Calderas" on Ganymede?
<h1>PIA01615: Swaths of Grooved Terrain on Ganymede</h1><div class="PIA01615" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>A swath of grooved terrain named Erech Sulcus cuts north-south across the ancient dark terrain of Marius Regio. The multiple scales of ubiquitous grooves in Erech Sulcus probably formed when tectonic forces pulled apart the icy surface of Jupiter's moon, Ganymede. Similar sets of faults occur in rift zones on Earth, as in eastern Africa. The southern edge of Erech Sulcus is truncated by the smoother bright terrain of Sippar Sulcus, trending roughly east-west. The relatively smooth appearance of Sippar Sulcus hints that icy volcanism once paved over the area.</p><p>North is to the top of the picture and the sun illuminates the surface from the right. The mosaic, centered at 16 degrees south latitude and 177 degrees longitude, covers an area approximately 950 by 560 kilometers. The resolution is 143 meters per picture element. The images were taken on May 7, 1997 at 15 hours, 24 minutes, 39 seconds Universal Time at a range of 14,263 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><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 URL <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. 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/PIA01615" onclick="window.open(this.href); return false;" title="Voir l'image PIA01615: Swaths of Grooved Terrain on Ganymede sur le site de la NASA">Voir l'image PIA01615: Swaths of Grooved Terrain on Ganymede sur le site de la NASA.</a></div>
PIA01615: Swaths of Grooved Terrain on Ganymede