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

<h1>PIA00328: Io, Showing Volcanic Plains and Mountains</h1><div class="PIA00328" lang="en" style="width:718px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Io's volcanic plains are shown in this Voyager 1 image. Also visible are numerous volcanic calderas and two large mountains (Euboea Montes, just above center, and Haemus Montes, at lower left). The plains include some distinct lava flows, such as those of Lerna Regio (lower right), and low mesas, such as Nemeas Planum (bottom center) and Dodona Planum (just left of center). This scene is about 1050 mi (1700 km) from left to right. The composition of Io's volcanic plains and lava flows has not been determined, but they could consist dominantly of sulfur or of silicates (such as basalt) coated with sulfurous condensates. The apparent erosion of the edges of some mesas suggests that they are composed of something volatile, possibly including a component of SO2 ice, which is observed spectroscopically to be widespread on Io. The high topographic relief in some areas, particularly of the montes, suggests that those areas are made primarily of silicate rock, which is much stronger than sulfur or SO2. The bright aureoles around several features probably consist of freshly deposited SO2 frost that was vented from cracks and volcanic conduits.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00328" onclick="window.open(this.href); return false;" title="Voir l'image PIA00328: Io, Showing Volcanic Plains and Mountains sur le site de la NASA">Voir l'image PIA00328: Io, Showing Volcanic Plains and Mountains sur le site de la NASA.</a></div>
PIA00328: Io, Showing Volcanic Plains and Mountains
<h1>PIA00361: Io Surface Deposits and Volcano</h1><div class="PIA00361" lang="en" style="width:619px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This color picture of Io, Jupiter's innermost Galilean satellite, was taken by Voyager 1 on the morning of March 5, 1979 at a range of 128,500 kilometers (77,100 miles). It is centered at 8 south latitude and 317 longitude. The width of the picture is about 1000 kilometers (600 miles). The diffuse reddish and orangish colorations are probably surface deposits of sulfur compounds, salts and possibly other volcanic sublimates. The dark spot with the irregular radiating pattern near the bottom of the picture may be a volcanic crater with radiating lava flows.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00361" onclick="window.open(this.href); return false;" title="Voir l'image PIA00361: Io Surface Deposits and Volcano sur le site de la NASA">Voir l'image PIA00361: Io Surface Deposits and Volcano sur le site de la NASA.</a></div>
PIA00361: Io Surface Deposits and Volcano
<h1>PIA00371: Jupiter - Io In Front of Jupiter's Turbulent Clouds</h1><div class="PIA00371" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This photograph of the southern hemisphere of Jupiter was obtained by Voyager 2 on June 25, 1979, at a distance of 12 million kilometers (8 million miles). The Voyager spacecraft is rapidly nearing the giant planet, with closest approach to occur at 4:23 pm PDT on July 9. Seen in front of the turbulent clouds of the planet is Io, the innermost of the large Galilean satellites of Jupiter. Io is the size of our moon. Voyager discovered in early March that Io is the most volcanically active planetary body known in the solar system, with continuous eruptions much larger than any that take place on the Earth. The red, orange, and yellow colors of Io are thought to be deposits of sulfur and sulfur compounds produced in these eruptions. The smallest features in either Jupiter or Io that can be distinguished in this picture are about 200 kilometers (125 miles) across; this resolution, it is not yet possible to identify individual volcanic eruptions. Monitoring of the erupture activity of Io by Voyager 2 will begin about July 5 and will extend past the encounter July 9. The Voyager Project is managed for NASA by the Jet Propulsion Laboratory.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00371" onclick="window.open(this.href); return false;" title="Voir l'image PIA00371: Jupiter - Io In Front of Jupiter's Turbulent Clouds sur le site de la NASA">Voir l'image PIA00371: Jupiter - Io In Front of Jupiter's Turbulent Clouds sur le site de la NASA.</a></div>
PIA00371: Jupiter - Io In Front of Jupiter's Turbulent Clouds
<h1>PIA00373: Io - Volcanic Eruption</h1><div class="PIA00373" lang="en" style="width:325px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This photo of a volcanic eruption on Jupiter's satellite Io (dark fountain-like feature near the limb) was taken March 4, 1979, about 12 hours before Voyager 1's closest approach to Jupiter. This and the accompanying photo present the evidence for the first active volcanic eruption ever observed on another body in the solar system. This photo taken from a distance of 310,000 miles (499,000 kilometers), shows a plume-like structure rising more than 60 miles (100 kilometers) above the surface, a cloud of material being produced by an active eruption. At least four eruptions have been identified on Voyager 1 pictures and many more may yet be discovered on closer analysis. On a nearly airless body like Io, particulate material thrown out of a volcano follows a ballistic trajectory, accounting for the dome-like shape of the top of the cloud, formed as particles reach the top of their flight path and begin to fall back. Spherical expansion of outflowing gas forms an even larger cloud surrounding the dust. Several regions have been identified by the infrared instrument on Voyager 1 as being several hundred degrees Fahrenheit warmer than surrounding terrain, and correlated with the eruptions. The fact that several eruptions appear to be going on simultaneously makes Io the most active surface in the solar system and suggests to scientists that Io is undergoing continuous volcanism, revising downward the age of Io's surface once again. JPL manages and controls the Voyager Project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00373" onclick="window.open(this.href); return false;" title="Voir l'image PIA00373: Io - Volcanic Eruption sur le site de la NASA">Voir l'image PIA00373: Io - Volcanic Eruption sur le site de la NASA.</a></div>
PIA00373: Io - Volcanic Eruption
<h1>PIA00374: Io - One of at Least Four Simultaneous Erupting Volcanic Eruptions</h1><div class="PIA00374" lang="en" style="width:220px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This photo of an active volcanic eruption on Jupiter's satellite Io was taken 1 hour, 52 minutes after the accompanying picture, late in the evening of March 4, 1979, Pacific time. On the limb of the satellite can be seen one of at least four simultaneous volcanic eruptions -- the first such activity ever observed on another celestial body. Seen against the limb are plume-like structures rising more than 60 miles (100 kilometers) above the surface. Several eruptions have been identified with volcanic structures on the surface of Io, which have also been identified by Voyager 1's infrared instrument as being abnormally hot -- several hundred degrees warmer than surrounding terrain. The fact that several eruptions appear to be occurring at the same time suggests that Io has the most active surface in the solar system and that volcanism is going on there essentially continuously. Another characteristic of the observed volcanism is that it appears to be extremely explosive, with velocities more than 2,000 miles an hour (at least 1 kilometer per second). That is more violent than terrestrial volcanoes like Etna, Vesuvius or Krakatoa.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00374" onclick="window.open(this.href); return false;" title="Voir l'image PIA00374: Io - One of at Least Four Simultaneous Erupting Volcanic Eruptions sur le site de la NASA">Voir l'image PIA00374: Io - One of at Least Four Simultaneous Erupting Volcanic Eruptions sur le site de la NASA.</a></div>
PIA00374: Io - One of at Least Four Simultaneous Erupting Volcanic Eruptions
<h1>PIA00375: Io - Volcano Loki and Loki Patera</h1><div class="PIA00375" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The detailed structure near the volcano Loki is like nothing seen elsewhere on Io. When this Voyager 1 picture was taken, the main eruptive activity came from the lower left of the dark linear feature (perhaps a rift) in the center. Below is the "lava lake," a U-shaped dark area about 200 kilometers across. In this specially processed image, detail can be seen in the dark surface of this feature, possibly due to "icebergs" of solid sulfur in a liquid sulfur lake. The IRIS on Voyager 1 found this "lava lake" to be the hottest region on Io, with a temperature about 150 degrees Celsius higher than that of the surrounding area.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00375" onclick="window.open(this.href); return false;" title="Voir l'image PIA00375: Io - Volcano Loki and Loki Patera sur le site de la NASA">Voir l'image PIA00375: Io - Volcano Loki and Loki Patera sur le site de la NASA.</a></div>
PIA00375: Io - Volcano Loki and Loki Patera
<h1>PIA00378: Io At 5 Million Miles</h1><div class="PIA00378" lang="en" style="width:680px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This photo of Jupiter's satellite Io was taken by Voyager 1 about 4:30 p.m. (PST) March 2, 1979. The spacecraft was about 5 million miles (8.3 million kilometers away). Voyager 1 was mapping Jupiter with the cameras and infrared instrument at the time the picture was taken. The hemisphere seen here is the one that always faces away from Jupiter. This photo shows details on Io never before seen. The smallest features are about 38 miles (70 kilometers) across. Near the center and slightly to the right can be seen several round features with dark centers and bright rims. They may be the first craters ever observed on Io. At this resolution scientists still cannot tell much about the origin of the features, which could be impact craters or of internal (volcanic) origin. No ray or ejecta patterns are obvious at this resolution.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00378" onclick="window.open(this.href); return false;" title="Voir l'image PIA00378: Io At 5 Million Miles sur le site de la NASA">Voir l'image PIA00378: Io At 5 Million Miles sur le site de la NASA.</a></div>
PIA00378: Io At 5 Million Miles
<h1>PIA00379: Volcanic Eruptions on Io</h1><div class="PIA00379" lang="en" style="width:140px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This dramatic view of Jupiter's satellite Io shows two simultaneously occurring volcanic eruptions. One can be seen on the limb, (at lower right) in which ash clouds are rising more than 150 miles (260 kilometers) above the satellite's surface. The second can be seen on the terminator (shadow between day and night) where the volcanic cloud is catching the rays of the rising sun. The dark hemisphere of Io is made visible by light reflected from Jupiter. Seen in Io's night sky, Jupiter looms almost 40 times larger and 200 times brighter than our own full Moon. This photo was taken by Voyager 1 on March 8, 1979, looking back 2.6 million miles (4.5 million kilometers) at Io, three days after its historic encounter. This is the same image in which Linda A. Morabito, a JPL engineer, discovered the first extraterrestrial volcanic eruption (the bright curved volcanic cloud on the limb). Jet Propulsion Laboratory manages and controls the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00379" onclick="window.open(this.href); return false;" title="Voir l'image PIA00379: Volcanic Eruptions on Io sur le site de la NASA">Voir l'image PIA00379: Volcanic Eruptions on Io sur le site de la NASA.</a></div>
PIA00379: Volcanic Eruptions on Io
<h1>PIA00401: Io: Cylindrical Projection</h1><div class="PIA00401" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">New multispectral image cube of Io from Voyager 2 images, simple cylindrical projection. Top: Natural color, Middle: enhanced color, Bottom: color-ratio composite. Improvements compared to old global mosaics of McEwen (1988) allow us to recognize new spectral units and relations and will facilitate comparisons to HST and Galileo observations.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00401" onclick="window.open(this.href); return false;" title="Voir l'image PIA00401: Io: Cylindrical Projection sur le site de la NASA">Voir l'image PIA00401: Io: Cylindrical Projection sur le site de la NASA.</a></div>
PIA00401: Io: Cylindrical Projection
<h1>PIA00491: Five Color Views of Io</h1><div class="PIA00491" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Five color views of Jupiter's moon Io, as seen by NASA's Galileo spacecraft camera, were taken between the 25th and the 29th of June, 1996 Universal Time. The color is a composite of the red, green, and violet filters of the on board imaging system with the brightness of the violet bandpass increased to provide better color discrimination. The full disk images were intended for color mapping of Io's surface and for comparison to Voyager images. Where images overlap several features can be seen to change in relative brightness, perhaps due to unusual light scattering behavior or active phenomena. The crescent images were intended primarily for color imaging of active volcanic plumes on the bright limb and these images showed that the Voyager-era Loki plumes were no longer active and revealed a new plume at Ra Patera. The smallest features which can be discerned in the 5 views range from 9 to 23 kilometers and provide our best look at Io since the 1979 Voyager flybys. Sub-spacecraft longitudes on Io (from upper left to lower right) are 69, 338, 264, 211, and 221 W. North is to the top.<p>Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00491" onclick="window.open(this.href); return false;" title="Voir l'image PIA00491: Five Color Views of Io sur le site de la NASA">Voir l'image PIA00491: Five Color Views of Io sur le site de la NASA.</a></div>
PIA00491: Five Color Views of Io
<h1>PIA00494: Io in front of Jupiter</h1><div class="PIA00494" lang="en" style="width:798px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Io, the most volcanic body in the solar system, is seen in front of Jupiter's cloudy atmosphere in this image from NASA's Galileo spacecraft, now orbiting the giant planet. This newly processed image is the best and highest resolution view of Io produced thus far by Galileo. Galileo was about 487,000 kilometers (about 302,000 miles) from Io when this was taken on September 7, 1996, and Jupiter was about 908,000 kilometers (about 564,000 miles) away. The image is centered on the side of Io that always faces away from Jupiter. The color in the image is composed of data taken in the near-infrared, green and violet filters of Galileo's solid-state imaging camera, and has been enhanced to emphasize the extraordinary variations in color and brightness that characterize Io's volcano-pocked face. The black and bright red materials correspond to the most recent volcanic deposits, probably no more than a few years old. The near-infrared filter makes Jupiter's atmosphere look blue. The active volcano Prometheus is seen near the right-center of the disk. Scientists are noting many changes that have occurred on Io's surface since the Voyager flybys 17 years ago, and even a few changes in the two months since Galileo's imaging of Io this summer.<p>The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00494" onclick="window.open(this.href); return false;" title="Voir l'image PIA00494: Io in front of Jupiter sur le site de la NASA">Voir l'image PIA00494: Io in front of Jupiter sur le site de la NASA.</a></div>
PIA00494: Io in front of Jupiter
<h1>PIA00495: Changing volcanoes on Io</h1><div class="PIA00495" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Volcanoes on Jupiter's moon Io are compared in these images from NASA's Galileo spacecraft (right) taken in early September of this year, and from the Voyager spacecraft (left) taken in 1979. Prometheus (bright ring in upper right) was first seen as an erupting volcano by the Voyager spacecraft and still features an active plume. A smaller active plume was discovered at the volcano Culann Patera (dark feature at lower left) by the Galileo spacecraft.<p>Prometheus has displayed similar characteristics such as size, shape and brightness to Galileo's cameras as it did to Voyager's. However, several intriguing differences are also apparent. There appears to be a new dark lava flow emanating from the vent of Prometheus, and the plume is now erupting from a position about 75 kilometers (46.5 miles) west from where the hot spot resided in 1979. It is not known if the plume source is the same or if the plume is now emanating from a new source. Overall, scientists studying Galileo images of Io see that a wide variety of surface changes have occurred on Io since 1979. The Galileo image was taken at a range of about 487,000 kilometers (about 302,000 miles) from Io. The Voyager image was taken from about 800,000 kilometers (about 500,000 miles).<p>The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00495" onclick="window.open(this.href); return false;" title="Voir l'image PIA00495: Changing volcanoes on Io sur le site de la NASA">Voir l'image PIA00495: Changing volcanoes on Io sur le site de la NASA.</a></div>
PIA00495: Changing volcanoes on Io
<h1>PIA00536: Geologic Landforms on Io</h1><div class="PIA00536" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Shown here is one of the highest-resolution images of Io (Latitude: -60 to +20 degrees, Longitude: 150 to 230 degrees) acquired by the Galileo spacecraft, revealing a great variety of landforms. There are rugged mountains several miles high, layered materials forming plateaus, and many irregular depressions called volcanic calderas. Similar landforms were seen near Io's south pole by the Voyager spacecraft, but Galileo has revealed that such landforms are ubiquitous. Several of the dark, flow-like features correspond to hot spots, and may be active lava flows. There are no landforms resembling impact craters, as the volcanism covers the surface with new deposits much more rapidly than the flux of comets and asteroids can create large impact craters.<p>North is to the top of the picture and the sun illuminates the surface from the left. The image covers an area 2000 kilometers wide and the smallest features that can be discerned are 2.5 kilometers in size. This image was taken on November 6th, 1996, at a range of 245,719 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.<p>Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00536" onclick="window.open(this.href); return false;" title="Voir l'image PIA00536: Geologic Landforms on Io sur le site de la NASA">Voir l'image PIA00536: Geologic Landforms on Io sur le site de la NASA.</a></div>
PIA00536: Geologic Landforms on Io
<h1>PIA00537: Volcanically Active Regions on Io</h1><div class="PIA00537" lang="en" style="width:493px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Shown here is a portion of one of the highest-resolution images of Io (Latitude: +10 to +60 degrees, Longitude: 180 to 225 degrees) acquired by the Galileo spacecraft, revealing immense lava flows and other volcanic landforms. Several high-temperature volcanic hot spots have been detected in this region by both the Near Infrared Mapping Spectrometer and the imaging system of Galileo. The temperatures are consistent with active silicate volcanism in lava flows or lava lakes (which reside inside irregular depressions called calderas). The large dark lava flow in the upper left region of the image is more than 400 km long, similar to ancient flood basalts on Earth and mare lavas on the Moon.<p>North is to the top of the picture and the sun illuminates the surface from the left. The image covers an area 1230 kilometers wide and the smallest features that can be discerned are 2.5 kilometers in size. This image was taken on November 6th, 1996, at a range of 245,719 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.<p>Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>..<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00537" onclick="window.open(this.href); return false;" title="Voir l'image PIA00537: Volcanically Active Regions on Io sur le site de la NASA">Voir l'image PIA00537: Volcanically Active Regions on Io sur le site de la NASA.</a></div>
PIA00537: Volcanically Active Regions on Io
<h1>PIA00583: High Resolution Global View of Io</h1><div class="PIA00583" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Io, the most volcanic body in the solar system is seen in the highest resolution obtained to date by NASA's Galileo spacecraft. The smallest features that can be discerned are 2.5 kilometers in size. There are rugged mountains several kilometers high, layered materials forming plateaus, and many irregular depressions called volcanic calderas. Several of the dark, flow-like features correspond to hot spots, and may be active lava flows. There are no landforms resembling impact craters, as the volcanism covers the surface with new deposits much more rapidly than the flux of comets and asteroids can create large impact craters. The picture is centered on the side of Io that always faces away from Jupiter; north is to the top.<p>Color images acquired on September 7, 1996 have been merged with higher resolution images acquired on November 6, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. The color is composed of data taken, at a range of 487,000 kilometers, in the near-infrared, green, and violet filters and has been enhanced to emphasize the extraordinary variations in color and brightness that characterize Io's face. The high resolution images were obtained at ranges which varied from 245,719 kilometers to 403,100 kilometers.<p>Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at 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/PIA00583" onclick="window.open(this.href); return false;" title="Voir l'image PIA00583: High Resolution Global View of Io sur le site de la NASA">Voir l'image PIA00583: High Resolution Global View of Io sur le site de la NASA.</a></div>
PIA00583: High Resolution Global View of Io
<h1>PIA00584: Global View of Io in various colors</h1><div class="PIA00584" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">These full disk views of Jupiter's volcanic moon, Io, use images which were acquired by NASA's Galileo spacecraft when Io, the spacecraft, and the sun were nearly all aligned (near zero degrees phase angle). This angle best shows color variations on the surface. The left frame is an enhanced color view combining images obtained with the near-infrared, green, and violet filters of Galileo's Solid State Imaging (CCD) system. The white areas are rich in sulfur dioxide frost. Yellow, brown, and red areas are rich in other sulfurous materials. The upper right frame combines the green, near-infrared, and one micrometer filters. The added information from the infrared part of the spectrum will help scientists characterize the type of volcanism that paints this active world. The lower right frame is a color ratio composite, in which ratios of different color combinations are displayed as red, green, and blue to reveal subtle color variations. North is to the top and the smallest features which can be discerned are 6 kilometers in size. These images were taken on December 18, 1996 at a range of 580,000 kilometers.<p>Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at 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/PIA00584" onclick="window.open(this.href); return false;" title="Voir l'image PIA00584: Global View of Io in various colors sur le site de la NASA">Voir l'image PIA00584: Global View of Io in various colors sur le site de la NASA.</a></div>
PIA00584: Global View of Io in various colors
<h1>PIA00703: Active Volcanic Plumes on Io</h1><div class="PIA00703" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This color image, acquired during Galileo's ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon (see inset at upper right), erupting over a caldera (volcanic depression) named Pillan Patera after a South American god of thunder, fire and volcanoes. The plume seen by Galileo is 140 kilometers (86 miles) high and was also detected by the Hubble Space Telescope. The Galileo spacecraft will pass almost directly over Pillan Patera in 1999 at a range of only 600 kilometers (373 miles).<p>The second plume, seen near the terminator (boundary between day and night), is called Prometheus after the Greek fire god (see inset at lower right). The shadow of the 75-kilometer (45- mile) high airborne plume can be seen extending to the right of the eruption vent. The vent is near the center of the bright and dark rings. Plumes on Io have a blue color, so the plume shadow is reddish. The Prometheus plume can be seen in every Galileo image with the appropriate geometry, as well as every such Voyager image acquired in 1979. It is possible that this plume has been continuously active for more than 18 years. In contrast, a plume has never been seen at Pillan Patera prior to the recent Galileo and Hubble Space Telescope images.<p>North is toward the top of the picture. The resolution is about 6 kilometers (3.7 miles) per picture element. This composite uses images taken with the green, violet and near infrared filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The images were obtained on June 28, 1997, at a range of more than 600,000 kilometers (372,000 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/PIA00703" onclick="window.open(this.href); return false;" title="Voir l'image PIA00703: Active Volcanic Plumes on Io sur le site de la NASA">Voir l'image PIA00703: Active Volcanic Plumes on Io sur le site de la NASA.</a></div>
PIA00703: Active Volcanic Plumes on Io
<h1>PIA00709: Massive Resurfacing of the Ionian Volcano Ra Patera</h1><div class="PIA00709" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Four views of the volcano Ra Patera on Jupiter's moon Io showing changes seen on June 27th, 1996 by the Galileo spacecraft as compared to views seen by the Voyager spacecraft during the 1979 flybys. Clockwise from upper left is a Voyager 1 high resolution image, a Voyager 1 color image, a Galileo color image, and a Voyager 2 color image. North is to the top of the picture. Observations obtained by J. Spencer and others with the Hubble Space Telescope had indicated a major change in recent years. The Galileo images reveal the detailed morphology of new deposits. Dark materials, previously confined to a summit caldera, appear to have overflowed the caldera walls to produce a small flow to the south and a larger flow to the southeast. New bright deposits covering an area of about 40,000 square kilometers (the size of New Jersey) surround the dark materials. The morphology of the bright materials suggests emplacement as lava flows rather than pyroclastics. Notice the lobate margins and how the bright materials embay a plateau in the upper left. The Voyager 1 images also reveal relatively bright lava flows emanating from Ra Patera, especially to the northeast. The colors of the flows match those of sulfur plus SO2 frost. Images are 953 km wide. 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/PIA00709" onclick="window.open(this.href); return false;" title="Voir l'image PIA00709: Massive Resurfacing of the Ionian Volcano Ra Patera sur le site de la NASA">Voir l'image PIA00709: Massive Resurfacing of the Ionian Volcano Ra Patera sur le site de la NASA.</a></div>
PIA00709: Massive Resurfacing of the Ionian Volcano Ra Patera
<h1>PIA00710: Changes near the Volcano Loki Patera on Io</h1><div class="PIA00710" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Four views of the volcano Loki Patera on Jupiter's moon Io showing changes seen on June 27th, 1996 by the Galileo spacecraft as compared to views seen by the Voyager spacecraft during the 1979 flybys. Clockwise from upper left is a Voyager 1 high resolution image, a Voyager 1 color image, a Galileo color image, and a Voyager 2 color image. North is to the top of the picture. During the Voyager flybys large dense volcanic plumes erupting from each end of the dark linear "fissure" to the northeast of the dark caldera and plume deposits obscured much of the surrounding surface. These dark jets are not visible in the Galileo image, and other images have confirmed that the Loki plumes were inactive during this Galileo encounter. Ground-based observers have determined that the Loki hot spot, historically the most energetic on Io, has been unusually dim. The fissure appears extended and elongated to the east and southwest, perhaps also resulting in a migration of the plume vents. There is an enlarged dark spot to the west of Loki. The materials just south and northeast of the caldera appear more reddish color. Images are 894 km wide. 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/PIA00710" onclick="window.open(this.href); return false;" title="Voir l'image PIA00710: Changes near the Volcano Loki Patera on Io sur le site de la NASA">Voir l'image PIA00710: Changes near the Volcano Loki Patera on Io sur le site de la NASA.</a></div>
PIA00710: Changes near the Volcano Loki Patera on Io
<h1>PIA00711: Unusual Volcanic Pyroclastic Deposits on Io</h1><div class="PIA00711" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Four views of Euboea Fluctus on Jupiter's moon Io showing changes seen on June 27th, 1996 by the Galileo spacecraft as compared to views seen by the Voyager spacecraft during the 1979 flybys. Clockwise from upper left is a Voyager 1 high resolution image, a Galileo enhanced color image, a Galileo image with simulated Voyager colors, and a Voyager 2 color image. North is to the top of the picture. The Galileo images show new diffuse deposits which have an unusual morphology for plume deposits. A diffuse yellowish deposit with a radius of 285 km extends to the northwest, whereas an intense reddish deposit marks a curving fallout margin to the southeast. This morphology may have resulted from the presence of a topographic obstruction to southeast of the vent. 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/PIA00711" onclick="window.open(this.href); return false;" title="Voir l'image PIA00711: Unusual Volcanic Pyroclastic Deposits on Io sur le site de la NASA">Voir l'image PIA00711: Unusual Volcanic Pyroclastic Deposits on Io sur le site de la NASA.</a></div>
PIA00711: Unusual Volcanic Pyroclastic Deposits on Io
<h1>PIA00712: Resurfacing of the Jupiter-facing hemisphere of Io</h1><div class="PIA00712" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Four views of the hemisphere of Io which faces Jupiter showing changes seen on June 27th, 1996 by the Galileo spacecraft as compared to views seen by the Voyager spacecraft during the 1979 flybys. Clockwise from upper left is a Voyager 1 high resolution image, a Voyager 1 color image, a Galileo color image, and a Voyager 2 color image. North is to the top of the picture. Voyager and Galileo images have been adjusted to provide comparable color balances similar to Voyager color. The most dramatic changes between Voyagers 1 and 2, just 4 months apart, were the effects of the eruptions of Surt (latitude +45 degrees) and Aten Patera (latitude -48 degrees) which darkened the caldera floors and left diffuse pyroclastic deposits covering areas about 1400 km in diameter (about the size of Alaska). In the Galileo image the Surt and Aten regions appear much more similar to the Voyager 1 pre-eruption images than to the Voyager 2 images. The plume deposits appear to have largely 'faded away' and the calderas have brightened. The Surt and Aten plume deposits had spectral properties similar to the plume deposits of Pele. Pele's deposits have not faded, suggesting that Pele had remained intermittently active whereas Surt and Aten are only rarely active. 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/PIA00712" onclick="window.open(this.href); return false;" title="Voir l'image PIA00712: Resurfacing of the Jupiter-facing hemisphere of Io sur le site de la NASA">Voir l'image PIA00712: Resurfacing of the Jupiter-facing hemisphere of Io sur le site de la NASA.</a></div>
PIA00712: Resurfacing of the Jupiter-facing hemisphere of Io
<h1>PIA00713: Surface Changes on Io</h1><div class="PIA00713" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Four views of an unnamed volcanic center (latitude 11, longitude 337) on Jupiter's moon Io showing changes seen on June 27th, 1996 by the Galileo spacecraft as compared to views seen by the Voyager spacecraft during the 1979 flybys. Clockwise from upper left is a Voyager 1 high resolution image, a Voyager 1 color image, a Galileo color image, and a Voyager 2 color image. North is to the top of the picture. This area has experienced many changes in appearance since Voyager images were acquired, including new dark and bright deposits. This region was a hot spot during Voyager 1. Images are 762 km wide. 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/PIA00713" onclick="window.open(this.href); return false;" title="Voir l'image PIA00713: Surface Changes on Io sur le site de la NASA">Voir l'image PIA00713: Surface Changes on Io sur le site de la NASA.</a></div>
PIA00713: Surface Changes on Io
<h1>PIA00714: Three Surface Changes on Io</h1><div class="PIA00714" lang="en" style="width:230px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Two views of three areas on Jupiter's moon Io showing changes seen on June 27th, 1996 by the Galileo spacecraft as compared to views seen by the Voyager spacecraft during the 1979 flybys. Galileo images are on the right; Voyager 2 images are on the left. North is to the top. At top (latitude +33, longitude 20) is a new volcanic feature consisting of a dark spot, perhaps a caldera floor, surrounded by a diffuse circular ring of reddish material, perhaps a plume deposit. The region in the middle corresponds to a hotspot observed by Earth-based observers on June 2nd, 1996. The Galileo image reveals new dark features, perhaps lava flows, within a field of lava flows (latitude +13, longitude 359). At bottom is the region near Sengen Patera (lower dark feature in the Voyager image; latitude -32, longitude 305). The dark materials have brightened or have been buried by new bright deposits by the time of the Galileo encounter. Earth-based observations indicated a hotspot in the Sengen Patera region also on June 2, 1996. Images are all 500 km wide. 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/PIA00714" onclick="window.open(this.href); return false;" title="Voir l'image PIA00714: Three Surface Changes on Io sur le site de la NASA">Voir l'image PIA00714: Three Surface Changes on Io sur le site de la NASA.</a></div>
PIA00714: Three Surface Changes on Io
<h1>PIA00715: Full Disk Views of Io (Natural and Enhanced Color)</h1><div class="PIA00715" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Three views of the full disk of Jupiter's volcanic moon, Io, each shown in natural and enhanced color. These three views, taken by Galileo in late June 1996, show about 75 percent of Io's surface. North is up. The top disks are intended to show the satellite in natural color (but colors will vary with display devices) while the bottom disks show enhanced color (near-infrared-, green-, and violet-filtered images) to highlight details of the surface. These images reveal that some areas on Io are truly red, whereas much of the surface is yellow or light greenish. (Accurate natural color renditions were not possible from the Voyager images taken during the 1979 flybys because there was no coverage in the red.) The reddish materials may be associated with very recent fragmental volcanic deposits (pyroclastics) erupted in the form of volcanic plumes. Dark materials appear in flows and on caldera floors. Bright white materials correspond to sulfur dioxide frost, and bright yellow materials appear to be in new flows such as those surrounding Ra Patera. The red material may be unstable since the color appears to fade over time. This fading appears to occur most rapidly in the equatorial region and more slowly over the polar regions; surface temperature may control the rate of transformation. Comparisons of these images to those taken by the Voyager spacecraft 17 years ago have revealed that many changes have occurred on Io. Since that time, about a dozen areas at least as large as the state of Connecticut have been resurfaced. Io's diameter is 3632 km. 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/PIA00715" onclick="window.open(this.href); return false;" title="Voir l'image PIA00715: Full Disk Views of Io (Natural and Enhanced Color) sur le site de la NASA">Voir l'image PIA00715: Full Disk Views of Io (Natural and Enhanced Color) sur le site de la NASA.</a></div>
PIA00715: Full Disk Views of Io (Natural and Enhanced Color)
<h1>PIA00717: Pele Comparisons Since 1979</h1><div class="PIA00717" lang="en" style="width:715px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>These frames detail the changes around Pele on Jupiter's moon Io, as seen by Voyager 1 (left), Voyager 2 (middle), and Galileo (right). The Voyager frames were taken in 1979 when the two spacecraft flew past Jupiter and it's moon Io. The Galileo view was obtained in June, 1996. Note the changes in the shape of the deposits further from the vent while the radial dark features closer to the vent show little change. The Voyager images use orange, blue, and violet filters. The Galileo image uses the green and violet filters of the Solid State Imaging system aboard the Galileo spacecraft and a synthetic blue. All three images are in a simple cylindrical projection and are approximately 1700 km x 1500 km. North is to the top.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the 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 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/PIA00717" onclick="window.open(this.href); return false;" title="Voir l'image PIA00717: Pele Comparisons Since 1979 sur le site de la NASA">Voir l'image PIA00717: Pele Comparisons Since 1979 sur le site de la NASA.</a></div>
PIA00717: Pele Comparisons Since 1979
<h1>PIA00718: Io's Pele Hemisphere</h1><div class="PIA00718" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Jupiter's moon Io with Pele prominently in view. The inset images are from the Voyager 1 (top) and 2 (bottom) spacecraft using the violet, blue, and orange filters. The large image is from Galileo, using the violet, green, and red filters. The colors in the Galileo image are closer to what the human eye would see. With the filters used in the Solid State Imaging system on Galileo, it is clear now that some of the recent volcanic deposits on Io are indeed very red, a point not resolved by Voyager. Scientists speculate that the red deposits are a form of Sulfur produced in volcanic eruptions on Io. Note the rapid changes seen in the shape of the distal (far from the vent) plume deposits from Pele between Voyagers 1 (April, 1979) and 2 (July, 1979). The Galileo image was obtained by the imaging system on board the spacecraft in June, 1996. North is to the top.</p><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/PIA00718" onclick="window.open(this.href); return false;" title="Voir l'image PIA00718: Io's Pele Hemisphere sur le site de la NASA">Voir l'image PIA00718: Io's Pele Hemisphere sur le site de la NASA.</a></div>
PIA00718: Io's Pele Hemisphere
<h1>PIA00738: Topography and Volcanoes on Io (color)</h1><div class="PIA00738" lang="en" style="width:598px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The images used to create this enhanced color composite of Io were acquired by NASA's Galileo spacecraft during its seventh orbit (G7) of Jupiter. Low sun angles near the terminator (day-night boundary near the left side of the image) offer lighting conditions which emphasize the topography or relief on the volcanic satellite. The topography appears very flat near the active volcanic centers such as Loki Patera (the large dark horse-shoe shaped feature near the terminator) while a variety of mountains and plateaus exist elsewhere. The big reddish-orange ring in the lower right is formed by material deposited from the eruption of Pele, Io's largest volcanic plume.<p>North is to the top of this picture which merges images obtained with the clear, red, green, and violet filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The resolution is 6.1 kilometers per picture element. The images were taken on April 4th, 1997 at a range of 600,000 kilometers.<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>Concurrent results from Galileo's exploration of Io appear in the October 15th, 1997 issue of Geophysical Research Letters. The papers are: Temperature and Area Constraints of the South Volund Volcano on Io from the NIMS and SSI Instruments during the Galileo G1 Orbit, by A.G. Davies, A.S. McEwen, R. Lopes-Gautier, L. Keszthelyi, R.W. Carlson and W.D. Smythe. High-temperature hot spots on Io as seen by the Galileo Solid-State Imaging (SSI) experiment, by A. McEwen, D. Simonelli, D. Senske, K. Klassen, L. Keszthelyi, T. Johnson, P. Geissler, M. Carr, and M. Belton. Io: Galileo evidence for major variations in regolith properties, by D. Simonelli, J. Veverka, and A. McEwen.<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/PIA00738" onclick="window.open(this.href); return false;" title="Voir l'image PIA00738: Topography and Volcanoes on Io (color) sur le site de la NASA">Voir l'image PIA00738: Topography and Volcanoes on Io (color) sur le site de la NASA.</a></div>
PIA00738: Topography and Volcanoes on Io (color)
<h1>PIA00739: Eclipse Images of Io (3 views)</h1><div class="PIA00739" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">These three images of Io in eclipse (top) show volcanic hot spots and airglow associated with volcanic plumes and Io's atmosphere. They were acquired by NASA's Galileo spacecraft during three separate orbits of Jupiter when the moon was in Jupiter's shadow. Brightnesses are color-coded from red which displays the highest intensity to dark blue which displays zero intensity (no light).<p>Below them are the corresponding views of Io in reflected sunlight, reprojected from a global mosaic of images obtained during Galileo's first and second orbits of Jupiter. These lit views help to identify the locations of the hot spots seen in the eclipse images. The grid marks are at 15 degree intervals of latitude and longitude. North is to the top.<p>In the eclipse images (top) small red ovals and perhaps some small green areas are due to thermal emission from volcanic hot spots with temperatures hotter than about 700 kelvin (about 1000 degrees Fahrenheit). Diffuse greenish areas seen near the limb or edge of the moon are probably the result of auroral and/or airglow emissions of neutral species of oxygen or sulfur in volcanic plumes and in Io's patchy atmosphere.<p>All images were acquired by the solid state imaging (CCD) system on NASA's Galileo spacecraft. The top left image was obtained during the spacecraft's fourth orbit (E4) on December 17, 1996, the top middle image during the sixth orbit (E6) on February 21, 1997, and the top right image during the first orbit (G1) on June 29th, 1996. The relatively long exposures used to obtain these eclipse images lead to some smearing of the picture elements which reduces the actual resolution. Unsmeared they would have resolutions of 17.6, 9.1, and 10.5 kilometers per picture element respectively (left to right).<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>Concurrent results from Galileo's exploration of Io appear in the October 15th, 1997 issue of Geophysical Research Letters. The papers are: Temperature and Area Constraints of the South Volund Volcano on Io from the NIMS and SSI Instruments during the Galileo G1 Orbit, by A.G. Davies, A.S. McEwen, R. Lopes-Gautier, L. Keszthelyi, R.W. Carlson and W.D. Smythe. High-temperature hot spots on Io as seen by the Galileo Solid-State Imaging (SSI) experiment, by A. McEwen, D. Simonelli, D. Senske, K. Klassen, L. Keszthelyi, T. Johnson, P. Geissler, M. Carr, and M. Belton. Io: Galileo evidence for major variations in regolith properties, by D. Simonelli, J. Veverka, and A. McEwen.<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/PIA00739" onclick="window.open(this.href); return false;" title="Voir l'image PIA00739: Eclipse Images of Io (3 views) sur le site de la NASA">Voir l'image PIA00739: Eclipse Images of Io (3 views) sur le site de la NASA.</a></div>
PIA00739: Eclipse Images of Io (3 views)
<h1>PIA00740: Topography of Io (color)</h1><div class="PIA00740" lang="en" style="width:410px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The images used to create this color composite of Io were acquired by Galileo during its ninth orbit (C9) of Jupiter and are part of a sequence of images designed to map the topography or relief on Io and to monitor changes in the surface color due to volcanic activity. Obtaining images at low illumination angles is like taking a picture from a high altitude around sunrise or sunset. Such lighting conditions emphasize the topography of the volcanic satellite. Several mountains up to a few miles high can be seen in this view, especially near the upper right. Some of these mountains appear to be tilted crustal blocks. Most of the dark spots correspond to active volcanic centers.<p>North is to the top of the picture which merges images obtained with the clear, red, green, and violet filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. . The resolution is 8.3 kilometers per picture element. The image was taken on June 27, 1997 at a range of 817,000 kilometers 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. 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/PIA00740" onclick="window.open(this.href); return false;" title="Voir l'image PIA00740: Topography of Io (color) sur le site de la NASA">Voir l'image PIA00740: Topography of Io (color) sur le site de la NASA.</a></div>
PIA00740: Topography of Io (color)
<h1>PIA00744: Arizona-sized Io Eruption</h1><div class="PIA00744" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">These images of Jupiter's volcanic moon, Io, show the results of a dramatic event that occurred on the fiery satellite during a five-month period. The changes, captured by the solid state imaging (CCD) system on NASA's Galileo spacecraft, occurred between the time Galileo acquired the left frame, during its seventh orbit of Jupiter, and the right frame, during its tenth orbit. A new dark spot, 400 kilometers (249 miles) in diameter, which is roughly the size of Arizona, surrounds a volcanic center named Pillan Patera. Galileo imaged a 120 kilometer (75 mile) high plume erupting from this location during its ninth orbit. Pele, which produced the larger plume deposit southwest of Pillan, also appears different than it did during the seventh orbit, perhaps due to interaction between the two large plumes. Pillan's plume deposits appear dark at all wavelengths. This color differs from the very red color associated with Pele, but is similar to the deposits of Babbar Patera, the dark feature southwest of Pele. Some apparent differences between the images are not caused by changes on Io's surface, but rather are due to differences in illumination, emission and phase angles. This is particularly apparent at Babbar Patera.<p>North is to the top of the images. The left frame was acquired on April 4th, 1997, while the right frame was taken on Sept. 19th, 1997. The images were obtained at ranges of 563,000 kilometers (350,000 miles) for the left image, and 505,600 kilometers (314,165 miles) for the right.<p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.<p>This image and other images and data received from Galileo are posted on the World Wide Web, 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/PIA00744" onclick="window.open(this.href); return false;" title="Voir l'image PIA00744: Arizona-sized Io Eruption sur le site de la NASA">Voir l'image PIA00744: Arizona-sized Io Eruption sur le site de la NASA.</a></div>
PIA00744: Arizona-sized Io Eruption