Galerie de photos de la planète Vénus

$<h1>PIA00244: Venus - Volcanic Domes East of Beta Regio</h1><div class="PIA00244" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Two unusual volcanic domes are shown in this Magellan full-resolution mosaic. The image covers an area 180 by 240 kilometers (120 by 160 miles) centered at 18 degrees north latitude, 303.5 degrees east longitude, just east of Beta Regio. The dome in the south center of the image is about 45 kilometers (30 miles) across, with a 20 kilometer (13 mile) caldera, or volcanic collapse crater, in the center. The dome in the northwest corner of the image is about 30 kilometers (20 miles) across with a small (5 kilometer or 3 mile) summit crater. The very bright radar return from the western flank of this dome indicates that it has steep slopes. The flanks of the volcanoes display prominent gullies which may have been formed by slumping of surface material or thermal erosion by lava flows. Variations in the brightness with the surrounding plains show the extent of lava flows which originated at these volcanoes. Curved or bowed fractures surrounding the southern structure indicate that there has been subsidence, or sinking, of the dome following eruptive activity.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00244" onclick="window.open(this.href); return false;" title="Voir l'image PIA00244: Venus - Volcanic Domes East of Beta Regio sur le site de la NASA">Voir l'image PIA00244: Venus - Volcanic Domes East of Beta Regio sur le site de la NASA.</a></div>$ PIA00244: Venus - Volcanic Domes East of Beta Regio	PIA00463: Venus - Barton Crater
Map_of_Venus.jpg	PIA00480: Venus - Impact Crater 'Isabella
Venus_a00.jpg
PIA00082: Venus - Lakshmi Region	$<h1>PIA00215: Venus - Alpha Regio</h1><div class="PIA00215" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The eastern edge of Alpha Regio is shown in this image centered at 30 degrees south latitude and 11.8 degrees east longitude (longitude on Venus is measured from 0 degrees to 360 degrees east). Seven circular, dome-like hills, averaging 25 kilometers (15 miles) in diameter with maximum heights of 750 meters (2,475 feet) dominate the scene. These features are interpreted as very thick lava flows that came from an opening on the relatively level ground, which allowed the lava to flow in an even pattern outward from the opening. The complex fractures on top of the domes suggest that if the domes were created by lava flows, a cooled outer layer formed and then further lava flowing in the interior stretched the surface. The domes may be similar to volcanic domes on Earth. Another interpretation is that the domes are the result of molten rock or magma in the interior that pushed the surface layer upward. The near-surface magma then withdrew to deeper levels, causing the collapse and fracturing of the dome surface. The bright margins possibly indicate the presence of rock debris on the slopes of the domes. Some of the fractures on the plains cut through the domes, while others appear to be covered by the domes. This indicates that active processes pre date and post date the dome-like hills. The prominent black area in the northeast corner of the image is a data gap. North is at the top of the image.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00215" onclick="window.open(this.href); return false;" title="Voir l'image PIA00215: Venus - Alpha Regio sur le site de la NASA">Voir l'image PIA00215: Venus - Alpha Regio sur le site de la NASA.</a></div>$ PIA00215: Venus - Alpha Regio
PIA00269: Venus - Stereo Image Pair of Crater Goeppert-Mayer	Venus_d270.jpg
Venus_d_pole-sud.jpg	$<h1>PIA00202: Venus - Aine Corona (F-MIDR 59S164)</h1><div class="PIA00202" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This Magellan radar image shows a region approximately 300 kilometers (180 miles) across, centered on 59 degrees south latitude, 164 degrees east longitude and located in a vast plain to the south of Aphrodite Terra. The data for this image was obtained in January 1991. The large circular structure near the center of the image is a corona, approximately 200 kilometers (120 miles) in diameter and provisionally named Aine Corona. Just north of Aine Corona is one of the flat-topped volcanic constructs known as 'pancake' domes for their shape and flap-jack appearance. This pancake dome is about 35 kilometers (21 miles) in diameter and is thought to have formed by the eruption of an extremely viscous lava. Another pancake dome is located inside the western parts of the annulus of the corona fractures. Complex fracture patterns like the one in the upper right of the image are often observed in association with coronae and various volcanic features. They are thought to form because magma beneath the surface follows pre-existing fracture patterns. When eruptions or other movements of the magma occur, the magma drains from the fractures and the overlying surface rock collapses. Other volcanic features associated with Aine Corona include a set of small domes, each less than 10 kilometers (6 miles) across, located along the southern portion of the annulus of fractures, and a smooth, flat region in the center of the corona, probably a relatively young lava flow. The range of volcanic features associated with coronae suggests that volcanism plays a significant role in their formation.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00202" onclick="window.open(this.href); return false;" title="Voir l'image PIA00202: Venus - Aine Corona (F-MIDR 59S164) sur le site de la NASA">Voir l'image PIA00202: Venus - Aine Corona (F-MIDR 59S164) sur le site de la NASA.</a></div>$ PIA00202: Venus - Aine Corona (F-MIDR 59S164)
$<h1>PIA00245: Venus - 600 Kilometer Segment of Longest Channel on Venus</h1><div class="PIA00245" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This compressed resolution radar mosaic from Magellan at 49 degrees north latitude, 165 degrees east longitude with dimensions of 460 by 460 kilometers (285 by 285 miles), shows a 600 kilometers (360 mile segment of the longest channel discovered on Venus to date. The channel is approximately 1.8 kilometers (1.1 miles) wide. At more than 7,000 kilometers (4,200 miles) long, it is several hundred kilometers longer than the Nile River, Earth's longest river, thus making it the longest known channel in the solar system. Both ends of the channel are obscured, however, so its original length is unknown. The channel was initially discovered by the Soviet Venera 15-16 orbiters which, in spite of their one kilometer resolution, detected more than 1,000 kilometers (620 miles) of the channel. These channel-like features are common on the plains of Venus. In some places they appear to have been formed by lava which may have melted or thermally eroded a path over the plains' surface. Most are 1 to 3 kilometers (0.6 to 2 miles) wide. They resemble terrestrial meandering rivers in some aspects, with meanders, cutoff bows and abandoned channel segments. However, Venus channels are not as tightly sinuous as terrestrial rivers. Most are partly buried by younger lava plains, making their sources difficult to identify. A few have vast radar-dark plains units associated with them, suggesting large flow volumes. These channels, with large deposits appear to be older than other channel types, as they are crossed by fractures and wrinkle ridges, and are often buried by other volcanic materials. In addition, they appear to run both upslope and downslope, suggesting that the plains were warped by regional tectonism after channel formation. Resolution of the Magellan data is about 120 meters (400 feet).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00245" onclick="window.open(this.href); return false;" title="Voir l'image PIA00245: Venus - 600 Kilometer Segment of Longest Channel on Venus sur le site de la NASA">Voir l'image PIA00245: Venus - 600 Kilometer Segment of Longest Channel on Venus sur le site de la NASA.</a></div>$ PIA00245: Venus - 600 Kilometer Segment of Longest Channel on Venus	Venus_a180.jpg
PIA00239: Venus - Crater Aurelia	Venus_04.jpg
Venus_03.jpg	Venus_a90.jpg
	$<h1>PIA00242: Venus - Ovda Regio</h1><div class="PIA00242" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This Magellan image shows part of the northern boundary of Ovda Regio, one of the large highlands ringing the equator of Venus. The scene consists largely of low-relief, rounded linear ridges. These ridges, 8-15 kilometers (5-9 miles) in width and 30-60 kilometers (20-40 miles) long, lie mostly along a 100-200 kilometer (60-120 mile) wide slope where the elevation drops 3 kilometers (2 miles) from Ovda Regio to the surrounding plains. Some of the ridges have been cut at right angles by extension fractures. Dark material, either lava or windblown dirt, fills the region between the ridges. The curvilinear, banded nature of these ridges suggests that crustal shortening, roughly oriented north-south, is largely responsible for their formation. Such crustal shortening was unexpected by Magellan scientists, who believed that Ovda Region, a likely site of hot upwelling from the interior of Venus, should be dominated by volcanism and crustal extension. This image, centered approximately at 1 degree north, 81 degrees east, measures 300 kilometers (190 miles) by 225 kilometers (140 miles) and was acquired by Magellan in November 1990.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00242" onclick="window.open(this.href); return false;" title="Voir l'image PIA00242: Venus - Ovda Regio sur le site de la NASA">Voir l'image PIA00242: Venus - Ovda Regio sur le site de la NASA.</a></div>$ PIA00242: Venus - Ovda Regio
$<h1>PIA00253: Venus - Sinuous Channel</h1><div class="PIA00253" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This full resolution radar mosaic from Magellan at 49 degrees south latitude, 273 degrees east longitude of an area with dimensions of 130 by 190 kilometers (81 by 118 miles), shows a 200 kilometer (124 mile) segment of a sinuous channel on Venus. The channel is approximately 2 kilometers (1.2 miles) wide. These channel-like features are common on the plains of Venus. In some places they appear to have been formed by lava which may have melted or thermally eroded a path over the plains' surface. Most are 1 to 3 kilometers (0.6 to 2 miles) wide. They resemble terrestrial rivers in some respects, with meanders, cutoff oxbows, and abandoned channel segments. However, Venus channels are not as tightly sinuous as terrestrial rivers. Most are partly buried by younger lava plains, making their sources difficult to identify. A few have vast radar-dark plains units associated with them, suggesting large flow volumes. These channels appear to be older than other channel types on Venus, as they are crossed by fractures and wrinkle ridges, and are often buried by other volcanic materials. In addition, they appear to run both upslope and downslope, suggesting that the plains were warped by regional tectonism after channel formation. Resolution of the Magellan data is about 120 meters (400 feet).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00253" onclick="window.open(this.href); return false;" title="Voir l'image PIA00253: Venus - Sinuous Channel sur le site de la NASA">Voir l'image PIA00253: Venus - Sinuous Channel sur le site de la NASA.</a></div>$ PIA00253: Venus - Sinuous Channel	$<h1>PIA00214: Venus - Lavinia Region Impact Craters</h1><div class="PIA00214" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Three large meteorite impact craters, with diameters that range from 37 to 50 kilometers (23 to 31 miles), are seen in this image of the Lavinia region of Venus. The image is centered at 27 degrees south latitude and 339 degrees east longitude (longitude on Venus is measured from 0 degrees to 360 degrees east), and covers an area 550 kilometers (342 miles) wide by about 500 kilometers (311 miles) long. Situated in a region of fractured plains, the craters show many features typical of meteorite impact craters, including rough (bright) material around the rim, terraced inner walls and central peaks. Numerous domes, probably caused by volcanic activity, are seen in the southeastern corner of the mosaic. The domes range in diameter from 1 to 12 kilometers (0.6 to 7 miles). Some of the domes have central pits that are typical of some types of volcanoes. North is at the top of the image.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00214" onclick="window.open(this.href); return false;" title="Voir l'image PIA00214: Venus - Lavinia Region Impact Craters sur le site de la NASA">Voir l'image PIA00214: Venus - Lavinia Region Impact Craters sur le site de la NASA.</a></div>$ PIA00214: Venus - Lavinia Region Impact Craters
$<h1>PIA00261: Venus - Volcanos in Guinevere Planitia</h1><div class="PIA00261" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This image, with radar illumination from west to east, shows three unusual volcanoes located in the Guinevere Planitia lowland. At the center of the image is a large feature (50 kilometers or 31 miles in diameter) with an unusual shape; very round when viewed from above with steep slides and a flat top. These volcanoes are believed to be the result of relatively thick and sticky (viscous) lava flows that originated from a point source. Although a faint remnant of its original circular shape is preserved, the northern rim of this center volcano has a steep scarp. The scarp is probably the result of material that has slid away from the volcano and subsequently has been covered by lava flows. This volcano overlaps another feature to the southwest that is about 45 kilometers (28 miles) in diameter and disrupted by many fractures. The southeastern volcano (25 kilometers or 15.5 miles in diameter) appears to be the highest of the three as its illuminated western edge has the brightest radar return. The scalloped edges give this feature a bottlecap-like appearance. The highly scalloped edges are probably the result of multiple material slides along the volcano margin.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00261" onclick="window.open(this.href); return false;" title="Voir l'image PIA00261: Venus - Volcanos in Guinevere Planitia sur le site de la NASA">Voir l'image PIA00261: Venus - Volcanos in Guinevere Planitia sur le site de la NASA.</a></div>$ PIA00261: Venus - Volcanos in Guinevere Planitia	$<h1>PIA00083: Venus - Adivar Crater</h1><div class="PIA00083" lang="en" style="width:685px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Many of the impact craters of Venus revealed by Magellan have characteristics unlike craters on any other planetary body. This 30-kilometer (18.6-mile) diameter crater, named Adivar crater for the Turkish educator and author Halide Adivar (1883-1964), is located just north of the western Aphrodite highland (9 degrees north latitude, 76 degrees east longitude). Surrounding the crater rim is ejected material which appears bright in the radar image due to the presence of rough fractured rock. A much broader area has also been affected by the impact, particularly to the west of the crater. Radar-bright materials, including a jet-like streak just west of the crater, extend for over 500 kilometers (310 miles) across the surrounding plains. A darker streak, in a horseshoe or paraboloidal shape, surrounds the bright area. Radar-dark (i.e., smooth) paraboloidal streaks were observed around craters in earlier Magellan images, but this is a rare bright crater streak. These unusual streaks, seen only on Venus, are believed to result from the interaction of crater materials (the meteoroid, ejecta, or both) and high-speed winds in the upper atmosphere. The precise mechanism that produces the streaks is poorly understood, but it is clear that the dense atmosphere of Venus plays an important role in the cratering process.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00083" onclick="window.open(this.href); return false;" title="Voir l'image PIA00083: Venus - Adivar Crater sur le site de la NASA">Voir l'image PIA00083: Venus - Adivar Crater sur le site de la NASA.</a></div>$ PIA00083: Venus - Adivar Crater
PIA00084: Venus - Eistla Region

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