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

<h1>PIA02599: Colorful Tupan Patera, Io</h1><div class="PIA02599" lang="en" style="width:736px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Wonderful colors in a volcanic crater named Tupan Patera on Jupiter's moon Io, as seen in this image from NASA's Galileo spacecraft, show varied results of lava interacting with sulfur-rich materials.<p>The colorfulness of the image is only slightly enhanced from what the human eye would see on the scene. The red in the image includes a small amount of infrared energy. Tupan Patera, named after a Brazilian thunder god, was seen as an active hot spot in earlier Galileo observations, but those <a href="/catalog/PIA02319">low-resolution views</a> did not show details of volcanic activity. This image taken in October 2001 at a resolution of 135 meters (443 feet) per picture element reveals the complex nature of the crater.<p>Tupan is now clearly shown to be a volcanic depression, about 75 kilometers (47 miles) across, surrounded by cliffs about 900 meters (3000 feet) tall. In the center is a large area that must be higher than the rest of the crater floor because it has not been covered by the dark lavas. Much of the area is coated with a diffuse red deposit that Galileo scientists believe has condensed from sulfur gas escaping from volcanic vents. The floor of Tupan is covered with a surreal pattern of dark black, green, red, and yellow materials. The black material is recent, still-warm lava. The yellow is presumed to be a mix of sulfurous compounds, and the green appears to form where red sulfur has interacted with the dark lavas. While Galileo scientists have found previous evidence for both molten sulfur and molten rock on Io, this image shows the best evidence to date of chemical reactions taking place between the two.<p>The intermingled patches of sulfur and lava are difficult to explain. The yellowish sulfur may be melting from within the crater walls over solidified but warm lava. The sulfur may boil away from the areas too hot for liquid sulfur to sit on, leaving patches where the dark lava is still visible.<p>North is to the top of the image and the Sun illuminates the surface from the upper right.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02599" onclick="window.open(this.href); return false;" title="Voir l'image PIA02599: Colorful Tupan Patera, Io sur le site de la NASA">Voir l'image PIA02599: Colorful Tupan Patera, Io sur le site de la NASA.</a></div>
PIA02599: Colorful Tupan Patera, Io
<h1>PIA02860: Io in Front of Jupiter</h1><div class="PIA02860" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Jupiter's four largest satellites, including Io, the golden ornament in front of Jupiter in this image from NASA's Cassini spacecraft, have fascinated Earthlings ever since Galileo Galilei discovered them in 1610 in one of his first astronomical uses of the telescope.<p>Images from Cassini that will be released over the next several days capture each of the four Galilean satellites in their orbits around the giant planet.<p>This true-color composite frame, made from narrow angle images taken on Dec. 12, 2000, captures Io and its shadow in transit against the disk of Jupiter. The distance of the spacecraft from Jupiter was 19.5 million kilometers (12.1 million miles). The image scale is 117 kilometers (73 miles) per pixel.<p>The entire body of Io, about the size of Earth's Moon, is periodically flexed as it speeds around Jupiter and feels, as a result of its non-circular orbit, the periodically changing gravitational pull of the planet. The heat arising in Io's interior from this continual flexure makes it the most volcanically active body in the solar system, with more than 100 active volcanoes. The white and reddish colors on its surface are due to the presence of different sulfurous materials. The black areas are silicate rocks.<p>Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02860" onclick="window.open(this.href); return false;" title="Voir l'image PIA02860: Io in Front of Jupiter sur le site de la NASA">Voir l'image PIA02860: Io in Front of Jupiter sur le site de la NASA.</a></div>
PIA02860: Io in Front of Jupiter
<h1>PIA02879: A New Year for Jupiter and Io</h1><div class="PIA02879" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Galilean satellite Io floats above the cloudtops of Jupiter in this image captured on the dawn of the new millennium, January 1, 2001 10:00 UTC (spacecraft time), two days after Cassini's closest approach. The image is deceiving: there are 350,000 kilometers -- roughly 2.5 Jupiters -- between Io and Jupiter's clouds. Io is the size of our Moon, and Jupiter is very big.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02879" onclick="window.open(this.href); return false;" title="Voir l'image PIA02879: A New Year for Jupiter and Io sur le site de la NASA">Voir l'image PIA02879: A New Year for Jupiter and Io sur le site de la NASA.</a></div>
PIA02879: A New Year for Jupiter and Io
<h1>PIA03527: Detailed View of Mountain and Craters at Tohil, Io</h1><div class="PIA03527" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Scientists pointed NASA's Galileo spacecraft camera at the Tohil region of Jupiter's moon Io to investigate the curious relationship between Io's mountains and its volcanoes.</p><p>This mosaic of Galileo images taken Oct. 16, 2001, shows details of the mountain called Tohil Mons (lower left), a small dark-floored volcanic crater, or "patera," bordered by mountain walls (middle), and intricate patterns of dark lava flows intertwined with bright material on the floor of a larger crater, Tohil Patera (upper right). An earlier <a href="/catalog/PIA02586">stereo observation</a> by Galileo revealed that Tohil Mons rises up to 6 kilometers (19,700 feet) above the surrounding plains. In contrast, shadows in the new images indicate the two paterae are only about 100 meters (330 feet) deep.</p><p>The new images were taken soon after sunrise at Tohil, with a resolution of 50 meters (160 feet) per picture element to reveal details never seen before. <a href="/catalog/PIA03600">Another view showing the entire mountain at lower resolution</a> was also acquired.</p><p>Despite Io's extremely high rate of volcanic activity, its mountains do not resemble volcanoes seen elsewhere in the solar system. Instead, the mountains appear to be formed by the uplift of large blocks of Io's crust. This image shows evidence of numerous landslides from the mountain (bottom left). However, one of the most surprising revelations from this observation is that despite the closeness of the small, dark-floored patera to the mountain walls, the patera floor is not covered with any landslide debris. This indicates that the patera floor has been resurfaced with lava more recently than any landslides have occurred. Another possibility is that this patera, like <a href="/catalog/PIA02596">others on Io</a>, is actually a lava lake and completely consumes debris that falls into it from the mountain. Galileo's infrared-mapping instrument has detected heat from the patera, indicating an active or very recent eruption.</p><p>North is to the top of the picture and the Sun illuminates the surface from the right. The mosaic is centered at 27.5 degrees south latitude and 160 degrees west longitude and covers 280 kilometers (170 miles) from upper right to lower left.</p><p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <a href="http://galileo.jpl.nasa.gov" class="external free" target="wpext">http://galileo.jpl.nasa.gov</a>. Background information and educational context for the images can be found at <a href="http://solarsystem.nasa.gov/galileo/gallery/index.cfm" class="external free" target="wpext">http://solarsystem.nasa.gov/galileo/gallery/index.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03527" onclick="window.open(this.href); return false;" title="Voir l'image PIA03527: Detailed View of Mountain and Craters at Tohil, Io sur le site de la NASA">Voir l'image PIA03527: Detailed View of Mountain and Craters at Tohil, Io sur le site de la NASA.</a></div>
PIA03527: Detailed View of Mountain and Craters at Tohil, Io
<h1>PIA03528: Collapsing Cliff at Telegonus Mensa, Io</h1><div class="PIA03528" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>These images of an area called Telegonus Mensa on Jupiter's moon Io, taken by NASA's Galileo spacecraft on Oct. 16, 2001, reveal a complex interplay of geologic processes.</p><p>Four small, high-resolution frames (9.6 meters, or 32 feet, per picture element) have been set into the larger context mosaic, which has a resolution of 42 meters (140 feet) per picture element. The illumination is from the upper right and north is to the top of the mosaic.</p><p>A fracture runs northwest from the lower right corner of the mosaic into the amphitheater in the center of the frame. A high-resolution image along this fracture reveals that lava has erupted from it.</p><p>The amphitheater itself is the site of extensive erosion, as the cliff has slumped southeastward under the influence of Io's gravity. High-resolution frames directly south of the amphitheater show another slumping cliff in detail. Flat tops of massive slump blocks—up to 6 kilometers (3.7 miles) long and 0.5 kilometers (0.3 miles) across—are illuminated by the Sun and cast shadows down the face of the cliff. Based on these shadows, Galileo scientists estimate that the cliff is 1 to 2 kilometers (3300 to 6600 feet) high. Just to the left of center a series of landslides can be seen, the longest of which extends 4 kilometers (2.5 miles).</p><p>The mosaic is centered at 21.45 degrees south latitude and 124.8 degrees west longitude and is 67 kilometers (42 miles) across.</p><p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <a href="http://galileo.jpl.nasa.gov" class="external free" target="wpext">http://galileo.jpl.nasa.gov</a>. Background information and educational context for the images can be found at <a href="http://solarsystem.nasa.gov/galileo/gallery/index.cfm" class="external free" target="wpext">http://solarsystem.nasa.gov/galileo/gallery/index.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03528" onclick="window.open(this.href); return false;" title="Voir l'image PIA03528: Collapsing Cliff at Telegonus Mensa, Io sur le site de la NASA">Voir l'image PIA03528: Collapsing Cliff at Telegonus Mensa, Io sur le site de la NASA.</a></div>
PIA03528: Collapsing Cliff at Telegonus Mensa, Io
<h1>PIA03529: Galileo's Last View of Tvashtar, Io</h1><div class="PIA03529" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This mosaic of Tvashtar Catena on Jupiter's moon Io, taken by NASA's Galileo spacecraft on Oct. 16, 2001, completes a series of views depicting changes in the region over a period of nearly two years. A catena is a chain of volcanic craters.</p><p>Streaks of light and dark deposits that radiate from the central volcanic crater, or "patera," are remnants of a tall plume that was seen erupting in earlier images.</p><p>This image and the others from <a href="/catalog/PIA02584">November 1999, February 2000</a>, <a href="/catalog/PIA02588">December 2000</a>, and <a href="/catalog/PIA02592">August 2001</a> were all taken to study aspects of this ever-changing, extremely active volcanic field.</p><p>Tvashtar is pictured here just 10 months after both the Galileo and Cassini spacecraft observed the eruption of a giant plume of volcanic gas emanating from it. The plume rose 385 kilometers (239 miles) high and blanketed terrain as far as 700 kilometers (435 miles) from its center.</p><p>Tvashtar has erupted in a variety of styles over the course of almost two years: (1) a <a href="/catalog/PIA02519">lava curtain</a> 50 kilometers (30 miles) long in the center patera, (2) a <a href="/catalog/PIA02550">giant lava flow or lava lake eruption</a> in the giant patera at far left, and (3) the large <a href="/catalog/PIA02588">plume eruption</a>. Therefore Galileo scientists expected that the lava flow margins or patera boundaries within Tvashtar would have changed drastically. However, the series of observations revealed little modification of this sort, suggesting that the intense eruptions at Tvashtar are confined by the local topography.</p><p>North is to the top of the mosaic, which is approximately 300 kilometers(186 miles) across and has a resolution of 200 meters (656 feet) per picture element.</p><p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <a href="http://galileo.jpl.nasa.gov" class="external free" target="wpext">http://galileo.jpl.nasa.gov</a>. Background information and educational context for the images can be found at <a href="http://solarsystem.nasa.gov/galileo/gallery/index.cfm" class="external free" target="wpext">http://solarsystem.nasa.gov/galileo/gallery/index.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03529" onclick="window.open(this.href); return false;" title="Voir l'image PIA03529: Galileo's Last View of Tvashtar, Io sur le site de la NASA">Voir l'image PIA03529: Galileo's Last View of Tvashtar, Io sur le site de la NASA.</a></div>
PIA03529: Galileo's Last View of Tvashtar, Io
<h1>PIA03530: Galileo's Best View of Loki Volcano on Io</h1><div class="PIA03530" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Light from the setting Sun falls across the Loki volcanic region on Jupiter's moon Io in this image taken by NASA's Galileo spacecraft on Oct. 16, 2001.<p>The image was taken to examine the relative depths and heights of features in the region. The Sun illuminates the surface from the right. Galileo's camera caught the large volcanic crater, or "patera" of Loki near the boundary between night and day. The image also shows several smaller craters plus shadows cast by the high peaks of several mountains.<p>Shadows cast by the low sun should reveal any topography associated with Loki, such as a plateau in the center of the patera or high patera walls. The near absence of shadows in this region surprised Galileo scientists, as they had expected much more pronounced topography near Loki.<p>Another surprising aspect of this image is that features that have been black in previous <a href="/catalog/PIA00375">Voyager</a> and <a href="/catalog/PIA02588">Galileo</a> images of Loki, such as the dark lava flows inside the patera, are here brighter than their surroundings. The best explanation is that the shiny, glassy surfaces of chilled lava flows look extremely dark when the Sun is directly overhead, but they reflect the Sun's light comparatively well when it shines at a low angle, in a similar manner to the reflective surfaces of bodies of water. Other volcanic paterae in this image show the same unusual reflectance as seen at Loki. Some of them are being viewed at such an angle that these reflections from lava flows are the brightest features in the image. This image tells us that lava flows on Io chill quickly and form glassy surfaces, not unlike recently cooled lava flows in Hawaii.<p>The image has a resolution of 1.1 kilometers (0.7 miles) per picture element. North is to the top of the picture.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03530" onclick="window.open(this.href); return false;" title="Voir l'image PIA03530: Galileo's Best View of Loki Volcano on Io sur le site de la NASA">Voir l'image PIA03530: Galileo's Best View of Loki Volcano on Io sur le site de la NASA.</a></div>
PIA03530: Galileo's Best View of Loki Volcano on Io
<h1>PIA03531: New plume vent near Zamama, Io</h1><div class="PIA03531" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The source area of what had been a towering volcanic plume two months earlier lies in the far-right frame of this mosaic of images taken of Jupiter's moon Io by NASA's Galileo spacecraft on Oct. 16, 2001.<p>The region in the images includes the Zamama lava flow in Jupiter's northern hemisphere. The Zamama flow field emanates from the northernmost of two small volcanoes in the far left frame. These lava flows were not present in Voyager images of Io, so they formed some time between the Voyager 1 flyby in 1979 and the first Galileo observations of Io in 1996. Galileo also observed Zamama during Io encounters in <a href="/catalog/PIA02504">1999</a>, and scientists identified narrow, long, dark lava flows thought to be similar to lava flows in Hawaii.<p>Moving northeast, the second and third frames of this mosaic contain lava flow fields and several unnamed volcanic depressions, called "paterae." It is unclear whether the broad, shield-like features or plateaus on which the paterae rest were created by eruptions from the paterae, or if they were preexisting features. Some fractures and dark lines suggest that the crust here is breaking up, creating cracks that magma can use to rise to the surface.<p>The far-right frame of this mosaic shows dark lava flows and bright spots. The bright spots are probably sulfur-bearing plume deposits, which are thought to be associated with the source of a <a href="/catalog/PIA02592">plume eruption</a> 500 kilometers (310 miles) high that was observed by the Galileo spacecraft in August, 2001. It was the largest plume eruption ever observed on Io.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03531" onclick="window.open(this.href); return false;" title="Voir l'image PIA03531: New plume vent near Zamama, Io sur le site de la NASA">Voir l'image PIA03531: New plume vent near Zamama, Io sur le site de la NASA.</a></div>
PIA03531: New plume vent near Zamama, Io
<h1>PIA03532: Volcanic Depression and Shield Volcano, Io</h1><div class="PIA03532" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This image taken by NASA's Galileo spacecraft on Oct. 16, 2001, near the equator of Jupiter's moon Io shows the contrast in volcanism styles found on Io.<p>The central feature is a large patera, or volcanic depression, almost 100 kilometers (60 miles) long. It may have formed after eruptions of lava emptied a subsurface magma chamber and left an empty space into which the crust collapsed. Evidence of lava flows associated with this patera, however, is difficult to find. Either the flows have been buried, or perhaps they never erupted and simply drained back deep into the crust.<p>On the right of the image is a small shield volcano, similar to volcanoes in Hawaii. It is rare for lavas on Io to be thick enough to pile up into shields around vents. They usually run out in thin, long flows instead. This shield abuts some very pale lava flows that emerged from a small vent to the west. These flows could be made of sulfur, like flows at Io's <a href="/catalog/PIA02598">Emakong Patera</a>. The vent is also surrounded by dark, diffuse material, which may be the result of lava erupted in an explosive, gas-rich eruption, similar to the 1980 eruption of Mount Saint Helens in Washington.<p>North is to the top of the image and the illumination is from the right. The image has a resolution of 330 meters (1,080 feet) per picture element and is 340 (211 miles) kilometers across.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03532" onclick="window.open(this.href); return false;" title="Voir l'image PIA03532: Volcanic Depression and Shield Volcano, Io sur le site de la NASA">Voir l'image PIA03532: Volcanic Depression and Shield Volcano, Io sur le site de la NASA.</a></div>
PIA03532: Volcanic Depression and Shield Volcano, Io
<h1>PIA03533: Amirani Lava Flow on Io</h1><div class="PIA03533" lang="en" style="width:720px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Amirani lava flow on Jupiter's moon Io appears to be made up of many individual flows; the newest flows are the brightest spots in this infrared image from NASA's Galileo spacecraft.<p>The thermal map from Galileo's near-infrared mapping spectrometer instrument is presented on the left, beside a reference picture of the same area from Galileo's camera. The infrared image uses false color to indicate intensity of glowing at a wavelength of 5 microns. White, reds and yellows indicate hotter regions; blues are cold. North is to the top.<p>Amirani is the largest active lava flow known in the solar system. Galileo has previously observed many <a href="/catalog/PIA02585"> changes in its flows</a>. In this infrared image, Amirani includes the two brightest spots and two others closest to that pair. The image also shows three other active volcanoes on Io: Maui (lower left, corresponding to a dark, roughly circular area in the reference image), Dusurra (top, corresponding to the dark, roughly circular area at the top of the reference image) and an unnamed hot spot that appears as an elongated small feature in the reference image between Dussura and the Amirani flow.<p>Of Amirani's four bright areas, the one on the lower left corresponds to what is thought to be the flow's vent: a dark elongated crater surrounded by red materials. Red deposits are indicative of recent plume activity on Io. The other three bright areas along the flow correspond to where hot lavas are breaking out.<p>Notice that the dark flow going from the main flow to the left is not seen in the infrared image. This indicates that this flow has cooled and is no longer active. NASA's Voyager spacecraft detected a plume more than 20 years ago from a location near the end of this now-inactive flow. The plume was probably created by interaction of the hot flow with sulfur-dioxide frost, in the same way as Io's <a href="/catalog/PIA02512">Prometheus plume</a>. Once the flow cooled, the plume shut off.<p>This infrared image was taken on Aug. 6, 2001. It has a resolution of about 9 kilometers (6 miles) per picture element.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03533" onclick="window.open(this.href); return false;" title="Voir l'image PIA03533: Amirani Lava Flow on Io sur le site de la NASA">Voir l'image PIA03533: Amirani Lava Flow on Io sur le site de la NASA.</a></div>
PIA03533: Amirani Lava Flow on Io
<h1>PIA03534: Io in Infrared with Giant Plume's New Hot Spot</h1><div class="PIA03534" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Nine previously unknown volcanoes have been discovered from this infrared image of Jupiter's moon Io, acquired by NASA's Galileo spacecraft on Oct. 16, 2001.<p>The infrared image, on the right, serves as a thermal map to a section of Io's surface from pole to pole. An image from Galileo's camera showing the same face of Io (left) is included for correlating the heat-sensing infrared data with geological features apparent in visible wavelengths. The infrared image uses false color to portray the intensity with which the surface glows at the invisible wavelength of 5 microns, as observed by Galileo's near infrared mapping spectrometer instrument. White, reds and yellows indicate hotter regions; blues are cold. The resolution varies from 24 to 39 kilometers (15 to 24 miles) per picture element.<p>Some of the hot spots visible in this image were not seen in a similar infrared image taken just <a href="/catalog/PIA02591">10 weeks earlier</a> of an overlapping section of Io.<p>Three sites of major activity in the images are Prometheus, which is a bright spot at center left; Amirani, which is an elongated feature in the upper right; and the site where a giant plume was erupting in August, which is the bright spot near the top of the image.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03534" onclick="window.open(this.href); return false;" title="Voir l'image PIA03534: Io in Infrared with Giant Plume's New Hot Spot sur le site de la NASA">Voir l'image PIA03534: Io in Infrared with Giant Plume's New Hot Spot sur le site de la NASA.</a></div>
PIA03534: Io in Infrared with Giant Plume's New Hot Spot
<h1>PIA03535: Io in Infrared, Night and Day</h1><div class="PIA03535" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Hot eruption sites scattered across Jupiter's moon Io stand out dramatically in an infrared image taken Oct. 13, 2001, by NASA's Galileo spacecraft as it sped past this most volcanically active of all known worlds.<p>The infrared image (right) serves as a thermal map to nearly a full hemisphere of Io. An image from Galileo's camera showing the same face of Io (left) is included for correlating the heat-sensing infrared data with geological features apparent in visible wavelengths. When Galileo snapped the infrared shot, the left half of the hemisphere was actually in darkness and the right half in daylight.<p>The infrared image uses false color to portray the intensity with which the surface glows at the invisible wavelength of 5 microns, as observed by Galileo's near infrared mapping spectrometer instrument. White, reds and yellows indicate hotter regions; blues are cold. The resolution varies from 83 to 93 kilometers (52 to 58 miles) per picture element.<p>Four previously unknown volcanoes have been discovered from this image, including one also detected in another infrared image taken the same day. Those new-found hot spots are faint. Among the more easily identified brighter volcanoes in the image are the pair Pillan and Pele located near the left-hand edge at about 8 o'clock if the circular image is taken as a clock face. Marduk is located a little farther from the edge at 7 o'clock. The bright spot at about 2 o'clock is the site where a plume was seen erupting about 500 kilometers (320 miles) high 10 weeks before this image was taken.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03535" onclick="window.open(this.href); return false;" title="Voir l'image PIA03535: Io in Infrared, Night and Day sur le site de la NASA">Voir l'image PIA03535: Io in Infrared, Night and Day sur le site de la NASA.</a></div>
PIA03535: Io in Infrared, Night and Day
<h1>PIA03600: Tall Mountain, Tohil Mons, on Io</h1><div class="PIA03600" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Dramatic shadows across a mountainous landscape on Jupiter's moon Io reveal details of the topography around a peak named Tohil Mons in this mosaic created from images taken by NASA's Galileo spacecraft in October 2001.<p>Tohil Mons rises 5.4 kilometers (18,000 feet) above Io's surface, according to analysis of <a href="/catalog/PIA02586">stereo imaging</a> from earlier Galileo flybys of Io. The new images, with a resolution of 327 meters (1,070 feet) per picture element, were taken when the Sun was low in the sky, producing informative shadows. North is to the top and the Sun illuminates the surface from the upper right. The topographic features revealed include a very straight ridge extending southwest from the peak, 500- to 850-meter-high (1,640- to 2,790-foot-high) cliffs to the northwest and a curious pit immediately east of the peak.<p>Major questions remain about how Io's mountains form and how they are related to Io's ubiquitous volcanoes. Although Io is extremely active volcanically, few of its mountains appear to be volcanoes. However, two volcanic craters do lie directly to the northeast of Tohil's peak, a smaller dark-floored one and a larger one at the very edge of the mosaic. Furthermore, the shape of the pit directly east of the peak suggests a volcanic origin. Galileo scientists will use these images to investigate the geologic history of Tohil Mons and its relationship to the neighboring volcanic features.<p>The image is centered at 28 degrees south latitude and 161 degrees west longitude.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03600" onclick="window.open(this.href); return false;" title="Voir l'image PIA03600: Tall Mountain, Tohil Mons, on Io sur le site de la NASA">Voir l'image PIA03600: Tall Mountain, Tohil Mons, on Io sur le site de la NASA.</a></div>
PIA03600: Tall Mountain, Tohil Mons, on Io
<h1>PIA03884: Recent Eruption at Gish Bar Patera on Io</h1><div class="PIA03884" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This image taken by NASA's Galileo spacecraft reveals fresh lava in a wide pit named Gish Bar Patera on Jupiter's moon Io.<p>The patera, or depression, is quite large: 106.3 kilometers (66 miles) by 115.0 kilometers (71 miles). Galileo has detected volcanic activity at this site in the past, particularly in late 1996.<p>Galileo took this image on Oct. 16, 2001, during its 32nd orbit of Jupiter. Effects of a new eruption at Gish Bar can be seen in a comparison with images from 1999 (see figure below). The new eruption was first detected in infrared imaging by Galileo's near-infrared mapping spectrometer in August 2001. This visible-light image shows a pair of new lava flows. The largest runs to the western boundary and extends to the central and northern portions of the patera. The other flow corresponds to a secondary depression in the southeastern portion of the patera. Based on changes seen at this depression between July and October 1999, this is thought to be the site of an outburst seen by Earth-based observers in August 1999.<p><a href="/figures/PIA03884-fig1.png"></a><p>Gish Bar Patera lies at the base of an 11-kilometer (36,000-foot) mountain at 15.6 degrees north latitude, 89.1 degrees west longitude on Io. This image was taken from a distance of 25,000 kilometers (15,500 miles) and has a resolution of 250 meters (820 feet) per pixel. The Sun is straight behind the observer, an illumination angle that minimizes shadows and emphasizes inherent brightness variations rather than topography.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03884" onclick="window.open(this.href); return false;" title="Voir l'image PIA03884: Recent Eruption at Gish Bar Patera on Io sur le site de la NASA">Voir l'image PIA03884: Recent Eruption at Gish Bar Patera on Io sur le site de la NASA.</a></div>
PIA03884: Recent Eruption at Gish Bar Patera on Io
PIA03885-fig1.jpg
PIA03885-fig1.jpg
<h1>PIA03885: Io's Culann-Tohil Region in Color</h1><div class="PIA03885" lang="en" style="width:774px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Repeated flybys of Io by NASA's Galileo spacecraft have allowed scientists to develop an understanding of Io's Tohil-Culann region of interconnected volcanoes and mountains.<p>An active volcano named Culann Patera (top center) is one of the most colorful volcanoes on Jupiter's innermost large moon (see <a href="/catalog/PIA02535">PIA02535</a>). It lies just north of an enigmatic mountain called Tohil Mons (see <a href="/catalog/PIA03600">PIA03600</a>). This mosaic image uses high-resolution Galileo images of Culann (200 meters or 660 feet per picture element) from the November 1999 flyby and high-resolution images of Tohil (165 meters or 540 feet per picture element) from the February 2000 flyby, and combines them with lower-resolution color images (1.4 kilometers or 0.9 mile per picture element) taken during the July 1999 flyby. Using the combined information, Galileo scientists have identified relationships among many colorful features in this complex.<p>The volcano Culann has produced both dark black and dark red lava flows, as well as diffuse, inner and outer rings of red and yellowish sulfur particles from explosive plumes (for example, <a href="/catalog/PIA02502">PIA02502</a>). Molten silicate rock inside Culann must occasionally mix with subsurface reservoirs of sulfur and sulfur dioxide to produce the plume deposits. The green color at the center of Culann and inside the older volcano Tohil Patera (center right) forms when red sulfur plume deposits land on dark black silicate lava flows and form a green veneer. The large white patch in southwestern Tohil Patera is rich in sulfur dioxide, and comparison with higher-resolution views (for example, <a href="/catalog/PIA03527">PIA03527</a>) suggests that this might be a region of cold sulfur dioxide flows. The small white patches on the mountain Tohil Mons might be deposits of sulfur dioxide snow that accumulate in grooves and at the bases of steep slopes in colder areas on the mountain. At upper right is a global view of Io showing the location of the mosaic.<p>Although Tohil Mons rises up to 6 kilometers (19,700 feet) above Io's plains, it is difficult to see in this image because the Sun was behind Galileo at the time it was taken. The topography of the mountainous region is clearer in a mosaic of images taken when the Sun was low in the sky, with illumination from the right (see figure below) The side-lit mosaic combines a high-resolution (330 meters or 1,100 feet per picture element) image from October 2001 with lower-resolution color images (1.4 kilometers or 0.9 mile per picture element) from July 1999.<p><a href="/figures/PIA03885-fig1.png"></a><p>North is to the top of all images.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03885" onclick="window.open(this.href); return false;" title="Voir l'image PIA03885: Io's Culann-Tohil Region in Color sur le site de la NASA">Voir l'image PIA03885: Io's Culann-Tohil Region in Color sur le site de la NASA.</a></div>
PIA03885: Io's Culann-Tohil Region in Color
<h1>PIA03886: Mountains on Io at Sunset</h1><div class="PIA03886" lang="en" style="width:798px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>NASA's Galileo spacecraft captured this dramatic image of mountains on Io in February 2000.<p>The image was taken when the Sun was low in the sky, illuminating the scene from the left, so it reveals topographic details of Io's surface. A low scarp, roughly 250 meters (820 feet) high, runs from the upper left toward the center of the image. Mongibello Mons, the jagged ridge at the left of the image, rises 7 kilometers (23,000 feet) above the plains of Io, higher than any mountain in North America.<p>Few of Io's mountains (see also <a href="/catalog/PIA02526">PIA02526</a>) resemble volcanoes. Instead, Galileo scientists believe that the mountains are formed when blocks of Io's crust are uplifted along thrust faults. Angular mountains are thought to be younger, while older mountains have more subdued topography, such as the rise near the top center of this image.<p>The image has a resolution of 335 meters (1,100 feet) per picture element. North is to the top of the image.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03886" onclick="window.open(this.href); return false;" title="Voir l'image PIA03886: Mountains on Io at Sunset sur le site de la NASA">Voir l'image PIA03886: Mountains on Io at Sunset sur le site de la NASA.</a></div>
PIA03886: Mountains on Io at Sunset
<h1>PIA03887: Potential Source of Sulfur Flow on Io</h1><div class="PIA03887" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">A field of bright lava flows next to a shield volcano could be a source of recent sulfur volcanism on Io, as detected by instruments aboard NASA's Galileo spacecraft.<p>The mosaic at left combines higher-resolution images (330 meters or about 1080 feet per picture element) taken in October 2001 with lower-resolution color images (1.4 kilometers or 0.9 mile per picture element) taken in July 1999 by Galileo's solid-state imaging camera.<p>By comparing these images with a map of hot spots taken in February by Galileo's near-infrared mapping spectrometer (lower right), Galileo scientists noted that a new hot spot west of the active volcano Prometheus became bright in February 2000 and dimmed later. This hot spot appears to correspond with the bright flow field just west of a recently discovered shield volcano (see <a href="/catalog/PIA03532">PIA03532</a>), which is the only fresh volcanic material in the area.<p>The relatively low intensity of the February 2000 hot spot in the infrared data suggests a low-temperature eruption, consistent with sulfur lava rather than silicate lava as found elsewhere on Io and also on Earth. Sulfur lavas are thought to cool to a gray-yellow color on Io, as seen in the new flow field visible in the camera image. This bright flow field could be the best example of active sulfur lava flows deposited on Io during the Galileo mission. At upper right is a global view of Io showing the location of the more-detailed images.<p>The low temperature of this hot spot differs from many of Io's other active volcanoes, such as Pele, Tvashtar and Prometheus. Intense tidal flexing of Io helps keep the moon's interior molten, at some places producing silicate lavas hotter than any seen on Earth in billions of years. Io has the greatest known diversity of volcanic activity in the solar system.<p>North is to the top of all these images.<p>The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at <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://solarsystem.nasa.gov/planets/profile.cfm?Object=Jup_Io" target="_blank">http://galileo.jpl.nasa.gov/gallery/io.cfm</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA03887" onclick="window.open(this.href); return false;" title="Voir l'image PIA03887: Potential Source of Sulfur Flow on Io sur le site de la NASA">Voir l'image PIA03887: Potential Source of Sulfur Flow on Io sur le site de la NASA.</a></div>
PIA03887: Potential Source of Sulfur Flow on Io
<h1>PIA09244: An Eruption on Io</h1><div class="PIA09244" lang="en" style="width:500px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The first images returned to Earth by New Horizons during its close encounter with Jupiter feature the Galilean moon Io, snapped with the Long Range Reconnaissance Imager (LORRI) at 0840 UTC on February 26, while the moon was 2.5 million miles (4 million kilometers) from the spacecraft.</p><p>Io is intensely heated by its tidal interaction with Jupiter and is thus extremely volcanically active. That activity is evident in these images, which reveal an enormous dust plume, more than 150 miles high, erupting from the volcano Tvashtar. The plume appears as an umbrella-shaped feature of the edge of Io's disk in the 11 o'clock position in the right image, which is a long-exposure (20-millisecond) frame designed specifically to look for plumes like this. The bright spots at 2 o'clock are high mountains catching the setting sun; beyond them the night side of Io can be seen, faintly illuminated by light reflected from Jupiter itself. </p><p>The left image is a shorter exposure -- 3 milliseconds -- designed to look at surface features. In this frame, the Tvashtar volcano shows as a dark spot, also at 11 o'clock, surrounded by a large dark ring, where an area larger than Texas has been covered by fallout from the giant eruption. </p><p>This is the clearest view yet of a plume from Tvashtar, one of Io's most active volcanoes. Ground-based telescopes and the Galileo Jupiter orbiter first spotted volcanic heat radiation from Tvashtar in November 1999, and the Cassini spacecraft saw a large plume when it flew past Jupiter in December 2000. The Keck telescope in Hawaii picked up renewed heat radiation from Tvashtar in spring 2006, and just two weeks ago the Hubble Space Telescope saw the Tvashtar plume in ultraviolet images designed to support the New Horizons flyby. </p><p>Most of those images will be stored onboard the spacecraft for downlink to Earth in March and April.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09244" onclick="window.open(this.href); return false;" title="Voir l'image PIA09244: An Eruption on Io sur le site de la NASA">Voir l'image PIA09244: An Eruption on Io sur le site de la NASA.</a></div>
PIA09244: An Eruption on Io
<h1>PIA09248: Tvashtar's Plume</h1><div class="PIA09248" lang="en" style="width:420px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This dramatic image of Io was taken by the Long Range Reconnaissance Imager (LORRI) on New Horizons at 11:04 Universal Time on February 28, 2007, just about 5 hours after the spacecraft's closest approach to Jupiter. The distance to Io was 2.5 million kilometers (1.5 million miles) and the image is centered at 85 degrees west longitude. At this distance, one LORRI pixel subtends 12 kilometers (7.4 miles) on Io. </p><p>This processed image provides the best view yet of the enormous 290-kilometer (180-mile) high plume from the volcano Tvashtar, in the 11 o'clock direction near Io's north pole. The plume was first seen by the Hubble Space Telescope two weeks ago and then by New Horizons on February 26; this image is clearer than the February 26 image because Io was closer to the spacecraft, the plume was more backlit by the Sun, and a longer exposure time (75 milliseconds versus 20 milliseconds) was used. Io's dayside was deliberately overexposed in this picture to image the faint plumes, and the long exposure also provided an excellent view of Io's night side, illuminated by Jupiter. The remarkable filamentary structure in the Tvashtar plume is similar to details glimpsed faintly in 1979 Voyager images of a similar plume produced by Io's volcano Pele. However, no previous image by any spacecraft has shown these mysterious structures so clearly. </p><p>The image also shows the much smaller symmetrical fountain of the plume, about 60 kilometers (or 40 miles) high, from the Prometheus volcano in the 9 o'clock direction. The top of a third volcanic plume, from the volcano Masubi, erupts high enough to catch the setting Sun on the night side near the bottom of the image, appearing as an irregular bright patch against Io's Jupiter-lit surface. Several Everest-sized mountains are highlighted by the setting Sun along the terminator, the line between day and night. </p><p>This is the last of a handful of LORRI images that New Horizons is sending "home" during its busy close encounter with Jupiter -- hundreds of images and other data are being taken and stored onboard. The rest of the images will be returned to Earth over the coming weeks and months as the spacecraft speeds along to Pluto.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09248" onclick="window.open(this.href); return false;" title="Voir l'image PIA09248: Tvashtar's Plume sur le site de la NASA">Voir l'image PIA09248: Tvashtar's Plume sur le site de la NASA.</a></div>
PIA09248: Tvashtar's Plume
<h1>PIA09250: A Brilliant Plume</h1><div class="PIA09250" lang="en" style="width:498px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Long Range Reconnaissance Imager (LORRI) on New Horizons captured another dramatic picture of Jupiter's moon Io and its volcanic plumes, 19 hours after the spacecraft's closest approach to Jupiter on Feb. 28, 2007. LORRI took this 75 millisecond exposure at 0035 Universal Time on March 1, 2007, when Io was 2.3 million kilometers (1.4 million miles) from the spacecraft.</p><p>Io's dayside is deliberately overexposed to bring out faint details in the plumes and on the moon's night side. The continuing eruption of the volcano Tvashtar, at the 1 o'clock position, produces an enormous plume roughly 330 kilometers (200 miles) high, which is illuminated both by sunlight and "Jupiter light." </p><p>The shadow of Io, cast by the Sun, slices across the plume. The plume is quite asymmetrical and has a complicated wispy texture, for reasons that are still mysterious. At the heart of the eruption incandescent lava, seen here as a brilliant point of light, is reminding scientists of the fire fountains spotted by the Galileo Jupiter orbiter at Tvashtar in 1999.</p><p>The sunlit plume faintly illuminates the surface underneath. "New Horizons and Io continue to astonish us with these unprecedented views of the solar system's most geologically active body" says John Spencer, deputy leader of the New Horizons Jupiter Encounter Science Team and an Io expert from Southwest Research Institute.</p><p>Because this image shows the side of Io that faces away from Jupiter, the large planet does not illuminate the moon's night side except for an extremely thin crescent outlining the edge of the disk at lower right. Another plume, likely from the volcano Masubi, is illuminated by Jupiter just above this lower right edge. A third and much fainter plume, barely visible at the 2 o'clock position, could be the first plume seen from the volcano Zal Patera.</p><p>As in other New Horizons images of Io, mountains catch the setting Sun just beyond the terminator (the line dividing day and night). The most prominent, seen as a bright vertical line, is the edge of a plateau about 4.5 kilometers (15,000 feet) high, similar in altitude to the Colorado Rockies. Io itself has a diameter of 3,630 kilometers (about 2,250 miles). </p><p>The image is centered at Io coordinates 4 degrees S, 165 degrees W. It has been processed to reduce contrast, in order to show details over the full 1000-to-1 brightness range of the original data. </p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09250" onclick="window.open(this.href); return false;" title="Voir l'image PIA09250: A Brilliant Plume sur le site de la NASA">Voir l'image PIA09250: A Brilliant Plume sur le site de la NASA.</a></div>
PIA09250: A Brilliant Plume
<h1>PIA09254: A Burst of Color</h1><div class="PIA09254" lang="en" style="width:249px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>New Horizons captured this unique view of Jupiter's moon Io with its color camera -- the Multispectral Visible Imaging Camera (MVIC) -- at 00:25 UT on March 1, 2007, from a range of 2.3 million kilometers (1.4 million miles). The image is centered at Io coordinates 4 degrees south, 162 degrees west, and was taken shortly before the complementary Long Range Reconnaissance Imager (LORRI) photo of Io released on March 13 (see <a href="/catalog/PIA09250">PIA09250</a>), which had higher resolution but was not in color.</p><p>As in the LORRI picture, this processed image shows the nighttime glow of the Tvashtar volcano and its plume rising 330 kilometers (200 miles) into sunlight above Io's north pole. However, the MVIC picture reveals the intense red of the glowing lava at the plume source and the contrasting blue of the fine dust particles in the plume (similar to the bluish color of smoke), as well as more subtle colors on Io's sunlit crescent. The lower parts of the plume in Io's shadow, lit only by the much fainter light from Jupiter, are almost invisible in this rendition. Contrast has been reduced to show the large range of brightness between the plume and Io's disk.</p><p>A component of the Ralph imaging instrument, MVIC has three broadband color filters: blue (480 nanometers), red (620 nm) and infrared (850 nm); as well as a narrow methane filter (890 nm). Because the camera was designed for the dim illumination at Pluto, not the much brighter sunlight at Jupiter, the red and infrared filters are overexposed on Io's dayside. This image is therefore composed from the blue and methane filters only, and the colors shown are only approximations to those that the eye would see. Nevertheless, the human eye would easily see the red color of the volcano and the blue color of the plume.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09254" onclick="window.open(this.href); return false;" title="Voir l'image PIA09254: A Burst of Color sur le site de la NASA">Voir l'image PIA09254: A Burst of Color sur le site de la NASA.</a></div>
PIA09254: A Burst of Color
<h1>PIA09256: Two Moons Meet over Jupiter</h1><div class="PIA09256" lang="en" style="width:419px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This beautiful image of the crescents of volcanic Io and more sedate Europa was snapped by New Horizons' color Multispectral Visual Imaging Camera (MVIC) at 10:34 UT on March 2, 2007, about two days after New Horizons made its closest approach to Jupiter. </p><p>The picture was one of a handful of the Jupiter system that New Horizons took primarily for their artistic, rather than scientific value. This particular scene was suggested by space enthusiast Richard Hendricks of Austin, Texas, in response to an Internet request by New Horizons scientists for evocative, artistic imaging opportunities at Jupiter.</p><p>This image was taken from a range of 4.6 million kilometers (2.8 million miles) from Io and 3.8 million kilometers (2.4 million miles) from Europa. Although the moons appear close in this view, a gulf of 790,000 kilometers (490,000 miles) separates them. The night side of Io is illuminated here by light reflected from Jupiter, which is out of the frame to the right. Europa's night side is completely dark, in contrast to Io, because that side of Europa faces away from Jupiter. </p><p>Here, Io steals the show with its beautiful display of volcanic activity. Three volcanic plumes are visible. Most conspicuous is the enormous 300-kilometer (190-mile) -high plume from the Tvashtar volcano at the 11 o'clock position on Io's disk. Two much smaller plumes are barely visible: one from the volcano Prometheus, at the 9 o'clock position on the edge of Io's disk, and one from the volcano Amirani, seen between Prometheus and Tvashtar along Io's terminator (the line dividing day and night). The plumes appear blue because of the scattering of light by tiny dust particles ejected by the volcanoes, similar to the blue appearance of smoke. In addition, the contrasting red glow of hot lava can be seen at the source of the Tvashtar plume.</p><p>The images are centered at 1 degree north, 60 degrees west on Io, and 0 degrees north, 149 degrees west on Europa. The color in this image was generated using individual MVIC images at wavelengths of 480, 620 and 850 nanometers. The human eye is sensitive to slightly shorter wavelengths, from 400 to 700 nanometers, and thus would see the scene slightly differently. For instance, while the eye would notice the difference between the yellow and reddish brown colors of Io's surface and the paler color of Europa, the two worlds appear very similar in color to MVIC's longer-wavelength vision. The night side of Io appears greenish compared to the day side, because methane in Jupiter's atmosphere absorbs 850-nanometer light and makes Jupiter-light green to MVIC's "eyes."</p><p>MVIC is a component of the Ralph imaging instrument.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09256" onclick="window.open(this.href); return false;" title="Voir l'image PIA09256: Two Moons Meet over Jupiter sur le site de la NASA">Voir l'image PIA09256: Two Moons Meet over Jupiter sur le site de la NASA.</a></div>
PIA09256: Two Moons Meet over Jupiter
<h1>PIA09264: The Colors of the Night</h1><div class="PIA09264" lang="en" style="width:386px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The New Horizons Multicolor Visible Imaging Camera (MVIC) took this image of Jupiter's volcanic moon Io at 04:30 Universal Time on February 28, 2007, about one hour before New Horizons' closest approach to Jupiter, from a range of 2.7 million kilometers (1.7 million miles). Part of the Ralph imaging instrument, MVIC is designed for the very faint solar illumination at Pluto, and is too sensitive to image the brightly lit daysides of Jupiter's moons. Io's dayside is therefore completely overexposed in this image, and appears white and featureless. However, the Jupiter-lit nightside of Io and the giant plume from the Tvashtar volcano are well exposed, and the versions of the image shown here have been processed to bring out each of these features.<p></p>The scale of the original image is 53 kilometers (33 miles) per pixel; Io itself has a diameter of 3,630 kilometers (2,250 miles). <p></p>The nightside of Io (left panel) is illuminated brightly enough by Jupiter to reveal many details in full color to MVIC's sensitive vision. The nightside color has been corrected to account for the greenish hue of Jupiter's light as seen by MVIC -- see the April 2 Featured Image of Io and Europa (<a href="/catalog/PIA09256">PIA09256</a>) -- so the colors approximate what the human eye would see in daylight illumination. The image shows Io's reddish-brown polar areas and the yellow and white colors of its equatorial regions, mostly due to various forms of sulfur. <p></p>Several dark volcanic centers are also visible -- the most prominent, appearing as an elongated spot just above and to the right of the disk's center, is called Fjorgynn. Near the disk center, just over the night side of the terminator (the line separating day and night), is a row of three or four pale yellow patches, which likely are volcanic plumes catching the setting sun. These features have caught the attention of New Horizons scientists because no major plumes have been seen previously in this region of Io, and it is rare for Io's plumes to cluster so closely together.<p></p>The right panel shows the bluish color of the plume from Tvashtar, rising above the overexposed edge of Io's disk at the 11 o'clock position. The plume is blue because it contains fine dust that preferentially scatters blue light, in the same way that smoke appears blue. The red line on the edge of the disk, below the plume, is an artifact caused by the overexposure of Io's surface.<p></p>The image is centered at Io coordinates 26 degrees west, 6 degrees south, and is produced using MVIC's blue, red and near-infrared filters. In the original image, the overexposure of Io's dayside hemisphere caused extensive electronic "blooming" of the image toward the left and bottom edges of the frame, and this has been removed from the versions shown here.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09264" onclick="window.open(this.href); return false;" title="Voir l'image PIA09264: The Colors of the Night sur le site de la NASA">Voir l'image PIA09264: The Colors of the Night sur le site de la NASA.</a></div>
PIA09264: The Colors of the Night
<h1>PIA09354: Io in Eclipse 2</h1><div class="PIA09354" lang="en" style="width:179px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This image of Io eclipsed by Jupiter's shadow is a combination of several images taken by the New Horizons Long Range Reconnaissance Imager (LORRI) between 09:35 and 09:41 Universal Time on February 27, 2007, about 28 hours after the spacecraft's closest approach to Jupiter. North is at the top of the image.<p></p>In the darkness, only glowing hot lava, auroral displays in Io's tenuous atmosphere and the moon's volcanic plumes are visible. The brightest points of light in the image are the glow of incandescent lava at several active volcanoes. The three brightest volcanoes south of the equator are, from left to right, Pele, Reiden and Marduk. North of the equator, near the disk center, a previously unknown volcano near 22 degrees north, 233 degrees west glows brightly. (The dark streak to its right is an artifact.)<p></p>The edge of Io's disk is outlined by the auroral glow produced as intense radiation from Jupiter's magnetosphere bombards the atmosphere. The glow is patchy because the atmosphere itself is patchy, being denser over active volcanoes. At the 1 o'clock position the giant glowing plume from the Tvashtar volcano rises 330 kilometers (200 miles) above the edge of the disk, and several smaller plumes are also visible as diffuse glows scattered across the disk. Bright glows at the edge of Io on the left and right sides of the disk mark regions where electrical currents connect Io to Jupiter's magnetosphere.<p></p>New Horizons was 2.8 million kilometers (1.7 million miles) from Io when this picture was taken, and the image is centered at Io coordinates 2 degrees south, 238 degrees west. The image has been heavily processed to remove scattered light from Jupiter, but some artifacts remain, including a horizontal seam where two sets of frames were pieced together. Total exposure time for this image was 56 seconds.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09354" onclick="window.open(this.href); return false;" title="Voir l'image PIA09354: Io in Eclipse 2 sur le site de la NASA">Voir l'image PIA09354: Io in Eclipse 2 sur le site de la NASA.</a></div>
PIA09354: Io in Eclipse 2
<h1>PIA09355: Io Surface Changes</h1><div class="PIA09355" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This montage compares similar sides of Io photographed by the Galileo spacecraft in October 1999 (left) and the New Horizons spacecraft on February 27, 2007. The New Horizons image was taken with its Long Range Reconnaissance Imager (LORRI) from a range of 2.7 million kilometers (1.7 million miles).<p></p>Most features on Io have changed little in the seven-plus years between these images, despite continued intense volcanic activity. The largest visible feature is the dark oval composed of deposits from the Pele volcano, nearly 1,200 kilometers (750 miles) across its longest dimension. At high northern latitudes, the volcano Dazhbog is prominent as a dark spot in the New Horizons image, near the edge of the disk at the 11 o'clock position. This volcano is much less conspicuous in the Galileo image. This darkening happened after this 1999 Galileo image but before Galileo took its last images of Io in 2001.<p></p>A more recent change, discovered by New Horizons, can be seen in the southern hemisphere (circled). A new volcanic eruption near 55 degrees south, 290 degrees west has created a roughly circular deposit nearly 500 kilometers (300 miles) in diameter that was not seen by Galileo. Other New Horizons images show that the plume that created this deposit is still active.<p></p>The New Horizons image is centered at Io coordinates 8 degrees south, 269 degrees west.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09355" onclick="window.open(this.href); return false;" title="Voir l'image PIA09355: Io Surface Changes sur le site de la NASA">Voir l'image PIA09355: Io Surface Changes sur le site de la NASA.</a></div>
PIA09355: Io Surface Changes
<h1>PIA09357: Tvashtar Movie</h1><div class="PIA09357" lang="en" style="width:496px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p><a href="/archive/PIA09357.mov"></a><br />Click on the image for QuickTime movie of<br />Tvashtar Movie</p><p>Using its Long Range Reconnaissance Imager (LORRI), the New Horizons spacecraft captured the two frames in this "movie" of the 330-kilometer (200-mile) high Tvashtar volcanic eruption plume on Jupiter's moon Io on February 28, 2007, from a range of 2.7 million kilometers (1.7 million miles). The two images were taken 50 minutes apart, at 03:50 and 04:40 Universal Time, and because particles in the plume take an estimated 30 minutes to fall back to the surface after being ejected by the central volcano, each image likely shows an entirely different set of particles. The details of the plume structure look quite different in each frame, though the overall brightness and size of the plume remain constant.<p></p>Surface details on the nightside of Io, faintly illuminated by Jupiter, show the 5-degree change in Io's central longitude, from 22 to 27 degrees west, between the two frames.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09357" onclick="window.open(this.href); return false;" title="Voir l'image PIA09357: Tvashtar Movie sur le site de la NASA">Voir l'image PIA09357: Tvashtar Movie sur le site de la NASA.</a></div>
PIA09357: Tvashtar Movie
<h1>PIA09358: Io Through Different 'Eyes'</h1><div class="PIA09358" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This montage demonstrates New Horizons' ability to observe the same target in complementary ways using its diverse suite of instruments. Previously released views taken at visible and slightly longer infrared wavelengths with the Long Range Reconnaissance Imager (LORRI), New Horizons' high-resolution black-and-white camera, and the Multispectral Visible Imaging Camera (MVIC), its color camera, are here compared with a nearly simultaneous view from the Linear Etalon Imaging Spectral Array (LEISA), which observes its targets in more than 200 separate wavelengths of infrared light. This color LEISA view of Io (bottom right) combines three wavelength ranges, centered at 1.80, 2.04, and 2.31 micrometers.<p></p>The LORRI image (left) shows fine details on Io's sunlit crescent and in the partially sunlit plume from the Tvashtar volcano, and reveals the bright nighttime glow of the hot lavas at the source of the Tvashtar plume. The MVIC image (top right) shows the contrasting colors of the red lava and blue plume at Tvashtar, and the sulfur and sulfur dioxide deposits on Io's sunlit surface. The LEISA image shows that the glow of the Tvashtar volcano is even more intense at infrared wavelengths and reveals the infrared glow of at least 10 fainter volcanic hot spots on the moon's nightside. The brightest of these, Amirani/Maui, which is visible to the lower right of Tvashtar, is less than 4% as bright as Tvashtar. All of these are long-lived hot spots that have been observed previously by the Galileo orbiter. Further analysis of the LEISA data will provide information on the volcanoes' temperatures, and data on the sunlit crescent of Io will reveal details of Io's surface composition.<p></p>The LORRI, MVIC and LEISA images were taken March 1, 2007, at 00:35, 00:25 and 00:31 Universal Time, respectively, from a range of 2.3 million kilometers (1.4 million miles). The images are centered at Io coordinates 4 degrees south, 164 degrees west.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09358" onclick="window.open(this.href); return false;" title="Voir l'image PIA09358: Io Through Different 'Eyes' sur le site de la NASA">Voir l'image PIA09358: Io Through Different 'Eyes' sur le site de la NASA.</a></div>
PIA09358: Io Through Different 'Eyes'
<h1>PIA09359: Tvashtar Composite</h1><div class="PIA09359" lang="en" style="width:399px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Variations in the appearance of the giant plume from the Tvashtar volcano on Jupiter's moon Io are seen in this composite of the best photos taken by the New Horizons Long Range Reconnaissance Imager (LORRI) during its Jupiter flyby in late February-early March 2007.<p></p>New Horizons was fortunate to witness this unusually large plume during its brief Jupiter flyby; the Galileo Jupiter orbiter spent more than five years imaging the volcanic moon (between 1996 and 2001) without ever capturing such detailed pictures of a large Io plume. The plume is roughly 330 kilometers (200 miles) high. The cause of the fine wispy structure in the plume, which varies strikingly from image to image, is unknown, but these pictures may help scientists to understand the phenomenon.<p></p>The pictures were taken at distances ranging from 3.1 to 2.3 million kilometers (1.9 to 1.4 million miles), but they have been scaled to show the plume at the same relative size in every frame. Illumination conditions also vary: in the final image, Io's shadow cuts across the plume and hides all but its topmost regions, and the glow of hot lava can be seen on the nightside at the source of the plume. The times of the images, from top to bottom, are: February 26, 18:38 (Universal Time); February 26, 21:01; February 28, 03:50; February 28, 04:40; February 28, 11:04; and March 1, 00:35.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09359" onclick="window.open(this.href); return false;" title="Voir l'image PIA09359: Tvashtar Composite sur le site de la NASA">Voir l'image PIA09359: Tvashtar Composite sur le site de la NASA.</a></div>
PIA09359: Tvashtar Composite
<h1>PIA09360: A "Plumefall" on Io</h1><div class="PIA09360" lang="en" style="width:399px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>New Horizons took this image of Jupiter's volcanic moon Io with its Long Range Reconnaissance Imager (LORRI) at 15:15 Universal Time on February 28, 2007, nearly 10 hours after the spacecraft's closest approach to Jupiter. The image is centered at Io coordinates 5 degrees south, 92 degrees west, and the spacecraft was 2.4 million kilometers (1.5 million miles) from Io. Io's diameter is 3,640 kilometers (2,262 miles).<p></p>Io's dayside was deliberately overexposed in this image to bring out details on the nightside and in any volcanic plumes that might be present. Io cooperated by producing an enormous plume, 330 kilometers (200 miles) high, from the volcano Tvashtar. Near Io's north pole, Tvashtar was active throughout New Horizons' Jupiter encounter.<p></p>In this image, volcanic debris from the plume, illuminated by the setting sun, rains down onto Io's nightside. Hot, glowing lava at the source of the plume is the bright point of light on the sunlit side of the terminator (the line separating day and night). Elsewhere along the terminator, mountains catch the setting sun. The nightside of Io is lit up by light reflected from Jupiter.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09360" onclick="window.open(this.href); return false;" title="Voir l'image PIA09360: A "Plumefall" on Io sur le site de la NASA">Voir l'image PIA09360: A "Plumefall" on Io sur le site de la NASA.</a></div>
PIA09360: A "Plumefall" on Io