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

<h1>PIA01368: Jupiter's moon Io</h1><div class="PIA01368" lang="en" style="width:600px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture shows a special color reconstruction of one of the erupting volcanos on Io discovered by Voyager 1 during its encounter with Jupiter on the 4th and 5th of March. The picture was taken March 4 about 5:00 p.m. from a range of about half a million kilometers showing an eruption region on the horizon. This method of color analysis allows scientists to combine data from four pictures, taken in ultraviolet, blue, green and orange light. In this picture one can see the strong change in color of the erupting plume. The region that is brighter in ultraviolet light (blue in this image) is much more extensive than the denser, bright yellow region near the center of the eruption. Scientists will use data of this type to study the amount of gas and dust in the eruption and the size of dust particles. Preliminary analysis suggests that the bright ultraviolet part of the cloud may be due to scattered light from very fine particles (the same effect which makes smoke appear bluish).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01368" onclick="window.open(this.href); return false;" title="Voir l'image PIA01368: Jupiter's moon Io sur le site de la NASA">Voir l'image PIA01368: Jupiter's moon Io sur le site de la NASA.</a></div>
PIA01368: Jupiter's moon Io
<h1>PIA01485: South Polar Region of Io</h1><div class="PIA01485" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The South Polar region of Jupiter's moon Io, seen by Voyager 1 as it passed beneath.<p>JPL manages and controls the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01485" onclick="window.open(this.href); return false;" title="Voir l'image PIA01485: South Polar Region of Io sur le site de la NASA">Voir l'image PIA01485: South Polar Region of Io sur le site de la NASA.</a></div>
PIA01485: South Polar Region of Io
<h1>PIA01514: Io Surface Deposits and Volcanic Craters</h1><div class="PIA01514" lang="en" style="width:783px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture of Io, the innermost Galilean satellite, was taken by Voyager 1 on the morning of March 5, 1979 at a range of 377,000 kilometers (226,200 miles). The smallest features visible are about 10 kilometers (6 miles) across. The reddish, white and black areas are probably surface deposits, possibly consisting of mixtures of salts, sulfur and sublimate deposits of possible volcanic origin. Many of the black spots in these pictures are associated with craters of possible volcanic origin. The lack of impact craters on Io suggests that the surface is relatively young compared to the other Galilean satellites and some of the terrestrial planets such as Mercury and the Moon. JPL manages and controls the Voyager Project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01514" onclick="window.open(this.href); return false;" title="Voir l'image PIA01514: Io Surface Deposits and Volcanic Craters sur le site de la NASA">Voir l'image PIA01514: Io Surface Deposits and Volcanic Craters sur le site de la NASA.</a></div>
PIA01514: Io Surface Deposits and Volcanic Craters
<h1>PIA01530: Volcanic Activity on Io</h1><div class="PIA01530" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Io's volcanos continually resurface it, so that any impact craters have disappeared.<p>JPL manages the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01530" onclick="window.open(this.href); return false;" title="Voir l'image PIA01530: Volcanic Activity on Io sur le site de la NASA">Voir l'image PIA01530: Volcanic Activity on Io sur le site de la NASA.</a></div>
PIA01530: Volcanic Activity on Io
<h1>PIA01540: Hubble Clicks Images of Io Sweeping Across Jupiter</h1><div class="PIA01540" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">While hunting for volcanic plumes on Io, NASA's Hubble Space Telescope captured these images of the volatile moon sweeping across the giant face of Jupiter. Only a few weeks before these dramatic images were taken, the orbiting telescope snapped a portrait of one of Io's volcanoes spewing sulfur dioxide "snow."<p>These stunning images of the planetary duo are being released to commemorate the ninth anniversary of the Hubble telescope's launch on April 24, 1990. All of these images were taken with the Wide Field and Planetary Camera 2.<p>The three overlapping snapshots show in crisp detail Io passing above Jupiter's turbulent clouds. The close-up picture of Io (bottom right) reveal a 120-mile-high (200-kilometer) plume of sulfur dioxide "snow" emanating from Pillan, one of the moon's active volcanoes.<p>"Other observations have inferred sulfur dioxide 'snow' in Io's plumes, but this image offers direct observational evidence for sulfur dioxide 'snow' in an Io plume," explains John R. Spencer of Lowell Observatory in Flagstaff, Ariz.<p><b>A Trip Around Jupiter</b><p>The three snapshots of the volcanic moon rounding Jupiter were taken over a 1.8-hour time span. Io is roughly the size of Earth's moon but 2,000 times farther away. In two of the images, Io appears to be skimming Jupiter's cloud tops, but it's actually 310,000 miles (500,000 kilometers) away. Io zips around Jupiter in 1.8 days, whereas the moon circles Earth every 28 days.<p>The conspicuous black spot on Jupiter is Io's shadow and is about the size of the moon itself (2,262 miles or 3,640 kilometers across). This shadow sails across the face of Jupiter at 38,000 mph (17 kilometers per second). The smallest details visible on Io and Jupiter measure 93 miles (150 kilometers) across, or about the size of Connecticut.<p>These images were further sharpened through image reconstruction techniques. The view is so crisp that one would have to stand on Io to see this much detail on Jupiter with the naked eye.<p>The bright patches on Io are regions of sulfur dioxide frost. On Jupiter, the white and brown regions distinguish areas of high-altitude haze and clouds; the blue regions depict relatively clear skies at high altitudes.<p>These images were taken July 22, 1997, in two wavelengths: 3400 Angstroms (ultraviolet) and 4100 Angstroms (violet). The colors do not correspond closely to what the human eye would see because ultraviolet light is invisible to the eye.<p><b>Io: Jupiter's Volcanic Moon</b><p>In the close-up picture of Io (bottom right), the mound rising from Io's surface is actually an eruption from Pillan, a volcano that had previously been dormant.<p>Measurements at two ultraviolet wavelengths indicate that the ejecta consist of sulfur dioxide "snow," making the plume appear green in this false-color image. Astronomers increased the color contrast and added false colors to the image to make the faint plume visible.<p>Pillan's plume is very hot and its ejecta is moving extremely fast. Based on information from the Galileo spacecraft, Pillan's outburst is at least 2,240 degrees Fahrenheit (1,500 degrees Kelvin). The late bloomer is spewing material at speeds of 1,800 mph (2,880 kilometers per hour). The hot sulfur dioxide gas expelled from the volcano cools rapidly as it expands into space, freezing into snow.<p>Io is well known for its active volcanoes, many of which blast huge plumes of volcanic debris into space. Astronomers discovered Pillan's volcanic explosion while looking for similar activity from a known active volcano, Pele, about 300 miles (500 kilometers) away from Pillan. But Pele turned out to be peaceful. Io has hundreds of active volcanoes, but only a few, typically eight or nine, have visible plumes at any given time.<p>Scientists will get a closer look at Io later this year during a pair of close flybys to be performed by NASA's Galileo spacecraft, which has been orbiting Jupiter and its moons for nearly 3-1/2 years.<p>The first Galileo flyby is scheduled for Oct. 10 at an altitude of 379 miles (610 kilometers), and the other will occur on Nov. 25, when the spacecraft will fly only 186 miles (300 kilometers) above Io's fiery surface. If the spacecraft survives this daring journey into the intense Jovian radiation environment near Io, it will send back images with dramatically higher resolution than any obtained before, according to mission scientists.<p>The Hubble telescope image of Io's volcanic plume is a composite taken July 5, 1997, in three wavelengths: 2600 Angstroms (ultraviolet), 3400 Angstroms (ultraviolet), and 4100 Angstroms (violet).<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01540" onclick="window.open(this.href); return false;" title="Voir l'image PIA01540: Hubble Clicks Images of Io Sweeping Across Jupiter sur le site de la NASA">Voir l'image PIA01540: Hubble Clicks Images of Io Sweeping Across Jupiter sur le site de la NASA.</a></div>
PIA01540: Hubble Clicks Images of Io Sweeping Across Jupiter
<h1>PIA01604: Close-up color view of Io</h1><div class="PIA01604" lang="en" style="width:581px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This is the highest resolution color picture taken so far of Jupiter s volcanic moon Io by NASA s Galileo spacecraft. At 3 kilometers (about 2 miles) per picture element, the fiery satellite is seen against a backdrop of Jupiter's cloud tops, which appear blue in this false-color composite. Among the surprises seen on the moon s surface are several small, distinctly greenish patches and subtle violet hues at the cores and margins of bright sulfur dioxide-rich regions (like the one in the lower right). Dark spots, many flagged by bright red pyroclastic deposits, (deposits from explosive ejecta), mark the sites of current volcanic activity. Most of Io's riotous color is due to the presence of sulfur compounds, but the dark materials that make up the flows and calderas are probably silicate rock.</p><p>North is to the top of the picture. The images used to construct this composite were taken in the 1- micron, green and violet filters of the solid state imaging camera system on NASA's Galileo spacecraft. The images were taken on March 29, 1998 at a range of 294,000 kilometers (about 183,000 miles).</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01604" onclick="window.open(this.href); return false;" title="Voir l'image PIA01604: Close-up color view of Io sur le site de la NASA">Voir l'image PIA01604: Close-up color view of Io sur le site de la NASA.</a></div>
PIA01604: Close-up color view of Io
<h1>PIA01605: Io imaging during Galileo's 24th orbit</h1><div class="PIA01605" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>During its 14th orbit of Jupiter in March 29, 1998, NASA's Galileo spacecraft captured an image of Jupiter's moon, Io, that has the same lighting geometry that will exist during Io's close Io flyby on October 11, 1999 (the 24th orbit). The spacecraft groundtrack on Io is shown, with two-minute intervals marked by X's. The large X marks the location of closest approach, when Galileo will be just 500 kilometers (about 300 miles) above Io's surface. The curved boundary on the left marks the "terminator" or boundary between the lit day side and dark night side. Although the Pele volcano will be on the night side during the flyby, the hot lavas will be seen glowing in the dark. Other targets of interest that will be visible near closest approach are Pillan Patera, <a href="/catalog/PIA00744">the site of dramatic surface changes</a>, Reiden Patera, Marduk, the bright plains of Colchis regio, and the rugged Dorian Montes mountains. Active volcanic plumes and high-temperature hot spots have been seen at Pele, Pillan, and Marduk.</p><p>North is to the top of this image, which has a resolution of 2.6 kilometers (1.6 miles) per picture element. The image was taken at a range of 256,948 kilometers (about 160,000 miles) by the solid state imaging camera system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, D.C.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web on the Galileo mission home page at URL <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01605" onclick="window.open(this.href); return false;" title="Voir l'image PIA01605: Io imaging during Galileo's 24th orbit sur le site de la NASA">Voir l'image PIA01605: Io imaging during Galileo's 24th orbit sur le site de la NASA.</a></div>
PIA01605: Io imaging during Galileo's 24th orbit
<h1>PIA01626: Comparison of Amalthea to Io</h1><div class="PIA01626" lang="en" style="width:471px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Composite view of Amalthea and Io at the same scale. The visible part of Amalthea is about 150 kilometers across. The colors are approximate. Amalthea is actually much darker than Io, but is displayed at a similar brightness for ease of viewing. The <a href="/catalog/PIA01624">shape of Amalthea</a> is controlled largely by impact cratering and fragmentation. In contrast, Io, like Earth, has gravity sufficient to form it into a slightly ellipsoidal sphere. Amalthea is covered by craters because there are no processes which erode or cover them efficiently. On extremely volcanically active Io, impact craters are covered quickly by lavas and other volcanic materials. Some of the volcanic materials escape from Io and probably contribute to the reddish colors of Amalthea and the other small inner satellites.</p><p>The Amalthea and Io composites, obtained by the solid state imaging (SSI) camera on NASA's Galileo spacecraft on different orbits, were placed side by side for comparison purposes. The Amalthea composite combines data taken with the clear filter of the SSI system during orbit six, with lower resolution color images taken with the green, violet, and 1 micrometer filters during orbit 4. The Io data was obtained on July 2nd, 1998 (orbit 14) using the green, violet, and 1 micrometer filters.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at URL <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>."><a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.</a></p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01626" onclick="window.open(this.href); return false;" title="Voir l'image PIA01626: Comparison of Amalthea to Io sur le site de la NASA">Voir l'image PIA01626: Comparison of Amalthea to Io sur le site de la NASA.</a></div>
PIA01626: Comparison of Amalthea to Io
<h1>PIA01635: Io in Eclipse reveals High Temperature Hot Spots</h1><div class="PIA01635" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>These views of Jupiter's moon Io in the eclipse of the large planet's shadow are color coded so blue to yellow to red represents increasing brightness. The bright spots indicate the locations of volcanic vents on Io, which are spewing hot lava. This image and other data from NASA's Galileo spacecraft indicate that the lava at Pillan Patera (marked Pillan) exceeded 1,700 degrees kelvin (2,600 degrees Fahrenheit) and may have reached 2,000 degrees kelvin (3,140 degrees Fahrenheit). The hottest eruptions on Earth today reach temperatures of about 1,500 kelvin (2,240 degrees Fahrenheit), but hotter lava erupted billions of years ago.</p><p>The left and middle parts of this picture show a "raw" image presented without processing other than color coding and labeling. Small, bright pixels and clusters of pixels represent radiation interference. The bright vertical lines are column blemishes in the imaging detector (CCD). An image of Io was acquired through both a 1- micrometer filter (left) and clear filter on the Galileo solid state imaging camera system. Both images were exposed on the same frame; however, during the left exposure, the spacecraft platform moved, causing the exposure to slide toward the clear filter position. The middle view disc combines the two exposures.</p><p>The brightest hot spot at Pillan Patera was saturated in both filters, but the platform motion resulted in a horizontal line between the Pillan positions. The unsaturated line allows measurement of Pillan's temperature. For further information, see a report in Science magazine, Vol. 281, July 3, 1998, page 87.</p><p>The third view (right) is the processed clear filter data. Diffuse glows, produced by energized particles interacting with gases, highlight both the rim of Io's disc and active plumes such as Marduk. North is to the top of the picture. The resolution is 14.6 kilometers (9 miles) per picture element (pixel), but camera motion smeared the hot spots over about nine pixels. They appear bigger than they really are; modeling indicates the actual hot spots are much smaller than the pixels. The image was taken on June 28, 1997 at a range of 1,440, 000 kilometers (890,000 miles).</p><p>JPL manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01635" onclick="window.open(this.href); return false;" title="Voir l'image PIA01635: Io in Eclipse reveals High Temperature Hot Spots sur le site de la NASA">Voir l'image PIA01635: Io in Eclipse reveals High Temperature Hot Spots sur le site de la NASA.</a></div>
PIA01635: Io in Eclipse reveals High Temperature Hot Spots
<h1>PIA01637: Io's Aurorae</h1><div class="PIA01637" lang="en" style="width:689px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This eerie view of Jupiter's moon Io in eclipse (left) was acquired by NASA's Galileo spacecraft while the moon was in Jupiter's shadow. Gases above the satellite's surface produced a ghostly glow that could be seen at visible wavelengths (red, green, and violet). The vivid colors, caused by collisions between Io's atmospheric gases and energetic charged particles trapped in Jupiter's magnetic field, had not previously been observed. The green and red emissions are probably produced by mechanisms similar to those in Earth's polar regions that produce the aurora, or northern and southern lights. Bright blue glows mark the sites of dense plumes of volcanic vapor, and may be places where Io is electrically connected to Jupiter.</p><p>The viewing geometry is shown in the image on the right. North is to the top of the picture, and Jupiter is towards the right. The resolution is 13.5 kilometers (8 miles) per picture element. The images were taken on May 31, 1998 at a range of 1.3 million kilometers (800,000 miles) by Galileo's onboard solid state imaging camera system during the spacecraft's 15th orbit of Jupiter.</p><p>JPL manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web on the Galileo mission home page at <a href="http://galileo.jpl.nasa.gov"> http://galileo.jpl.nasa.gov</a>. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01637" onclick="window.open(this.href); return false;" title="Voir l'image PIA01637: Io's Aurorae sur le site de la NASA">Voir l'image PIA01637: Io's Aurorae sur le site de la NASA.</a></div>
PIA01637: Io's Aurorae
<h1>PIA01652: Sequence Showing Active Volcanic Plumes on Io</h1><div class="PIA01652" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>These four views of Jupiter's moon Io clearly show airborne plumes of gas and dust from two of Io's active volcanoes, Zamama and Prometheus. The bottom row consists of enlargements of the plume areas. The first view (left) depicts the tops of both plumes on Io's bright limb or edge. In the second image, an excellent view of Zamama on the bright limb reveals the umbrella-shaped structure. The third image also shows both plumes as bright spots against Io's illuminated crescent. In the fourth view (right) where the volcanic centers lie beyond the terminator (day-night boundary), the tall plumes are visible because they extend up into sunlight. The plumes have a height of about 100 kilometers (60 miles). Both plumes have been active throughout the Galileo tour of the Jovian system which began in 1996. Zamama, however, is considerably larger and brighter in these images from the spacecraft's eleventh orbit of Jupiter than when imaged previously. Prometheus was also active during 1979 flybys of NASA's Voyager spacecraft. There are two other much fainter plumes that can be detected on the bright limb of the third and fourth images. See if you can find them by changing the brightness levels of the images to enhance the dark regions.</p><p>North is to the top of the picture. To make the plumes easier to see, the colors have been enhanced by increasing the brightness at the blue end of the spectrum. Since the images shown were taken over an extended period of time, the resolutions range from 8 to 12 kilometers (5 to 7.5 miles) per picture element. The images were taken on November 7th and 8th, 1997by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft at ranges in excess of 800,000 kilometers (500,000 miles).</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL<a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01652" onclick="window.open(this.href); return false;" title="Voir l'image PIA01652: Sequence Showing Active Volcanic Plumes on Io sur le site de la NASA">Voir l'image PIA01652: Sequence Showing Active Volcanic Plumes on Io sur le site de la NASA.</a></div>
PIA01652: Sequence Showing Active Volcanic Plumes on Io
<h1>PIA01663: Highest Resolution mosaic of Io</h1><div class="PIA01663" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This global mosaic shows the highest resolution Galileo images available of Jupiter's moon, Io. North is to the top of the picture. The images, obtained at low sun illumination angles (high sun-target-spacecraft angles)which emphasize topographic shadows, were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft over the course of several orbits. The grid identifies the names and locations of several of Io's main features. Several active but as yet unnamed volcanic features are indicated by arrows. While volcanic centers are rather evenly distributed, almost all of the active plumes and long-lived hot spots seen over the span of NASA's Galileo mission at Jupiter or during the flyby's of NASA's Voyager spacecraft in 1979 are within 30 degrees of the equator.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL<a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01663" onclick="window.open(this.href); return false;" title="Voir l'image PIA01663: Highest Resolution mosaic of Io sur le site de la NASA">Voir l'image PIA01663: Highest Resolution mosaic of Io sur le site de la NASA.</a></div>
PIA01663: Highest Resolution mosaic of Io
<h1>PIA01667: Io's Pele Hemisphere After Pillan Changes</h1><div class="PIA01667" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This global view of Jupiter's moon, Io, was obtained during the tenth orbit of Jupiter by NASA's Galileo spacecraft. Io, which is slightly larger than Earth's moon, is the most volcanically active body in the solar system. In this enhanced color composite, deposits of sulfur dioxide frost appear in white and grey hues while yellowish and brownish hues are probably due to other sulfurous materials. Bright red materials, such as the prominent ring surrounding Pele, and "black" spots with low brightness mark areas of recent volcanic activity and are usually associated with high temperatures and surface changes. <a href="/catalog/PIA00744">One of the most dramatic changes</a> is the appearance of a new dark spot (upper right edge of Pele), 400 kilometers (250 miles) in diameter which surrounds a volcanic center named Pillan Patera. The dark spot did not exist in images obtained 5 months earlier, but Galileo imaged a 120 kilometer (75 mile) high plume erupting from this location during its ninth orbit.</p><p>North is to the top of the picture which was taken on September 19, 1997 at a range of more than 500,000 kilometers (310,000 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL<a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01667" onclick="window.open(this.href); return false;" title="Voir l'image PIA01667: Io's Pele Hemisphere After Pillan Changes sur le site de la NASA">Voir l'image PIA01667: Io's Pele Hemisphere After Pillan Changes sur le site de la NASA.</a></div>
PIA01667: Io's Pele Hemisphere After Pillan Changes
<h1>PIA01668: Key Volcanic Centers on Io</h1><div class="PIA01668" lang="en" style="width:708px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>These views of the key volcanic centers on Jupiter's moon, Io, merge color data with higher resolution mosaics. They show the color units in relation to surface features, and fine brightness variations such as volcanic flows. The images in frames "a" through "g" are all scaled to the same proportions. Frame "a" is 575 kilometers (356 miles) across.</p><p>These images show that some of the most colorful and high-contrast regions on Io are associated with the most active volcanoes. They also illustrate that fresh-appearing lava flows are often associated with active plumes(for example at Loki, Prometheus, Culann, Marduk, Volund, Zamama, Maui, and Amirani). It is possible that the plumes result from interaction between the advancing flows and the SO2-rich surface deposits, analogous to the plumes that form when lava flows into a body of water (for example, in Hawaii).</p><p>North is to the top of the picture. The color has been enhanced. The images were obtained with the green, violet, and 756 micrometer filters of the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL<a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at URL <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/PIA01668" onclick="window.open(this.href); return false;" title="Voir l'image PIA01668: Key Volcanic Centers on Io sur le site de la NASA">Voir l'image PIA01668: Key Volcanic Centers on Io sur le site de la NASA.</a></div>
PIA01668: Key Volcanic Centers on Io
<h1>PIA01971: Volcanic explosion on Io</h1><div class="PIA01971" lang="en" style="width:600px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">VOLCANIC EXPLOSION ON IO: Voyager 1 acquired this image of Io on March 4 at 5:30 p.m. (PST) about 11 hours before closest approach to the Jupiter moon. The distance to Io was about 490,000 kilometers (304,000 miles). An enormous volcanic explosion can be seen silhouetted against dark space over Io's bright limb. The brightness of the plume has been increased by the computer as it is normally extremely faint, whereas the relative color of the plume (greenish white) has been preserved. At this time solid material had been thrown up to an altitude of about 100 miles. This requires an ejection velocity from the volcanic vent of about 1200 miles per hour, material reaching the crest of the fountain in several minutes. The vent area is a complex circular structure consisting of a bright ring about 300 kilometers in diameter and a central region of irregular dark and light patterns. Volcanic explosions similar to this occur on the Earth when magmatic gases expand explosively as material is vented. On Earth water is the major gas driving the explosion. Because Io is thought to be extremely dry, scientists are searching for other gases to explain the explosion. JPL manages and controls the Voyager Project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01971" onclick="window.open(this.href); return false;" title="Voir l'image PIA01971: Volcanic explosion on Io sur le site de la NASA">Voir l'image PIA01971: Volcanic explosion on Io sur le site de la NASA.</a></div>
PIA01971: Volcanic explosion on Io
<h1>PIA01986: Io - Jupiter's inner satellite</h1><div class="PIA01986" lang="en" style="width:300px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">The trailing face of Jupiter's inner satellite Io is shown in this photo taken by Voyager 1 on March 3, 1979, from a distance of 1.7 million miles. A bright yellow-orange equatorial band (lower left to upper right) separates the darker reddish-brown polar zones. The north pole is at upper left. Characteristic of Io's surface is the profusion of dark spots commonly surrounded by rings of brighter material. The smallest dark spot visible in this view is 30 kilometers wide; the largest, on the left is about 400 kilometers across. The large heart-shaped feature with a dark spot near its center could be Io's equivalent of an impact basin such as Mare Orientale on the Moon. Its outer dimensions are about 800 by 1000 km. It is located near (15 S by 260 W). Subsequent high-resolution coverage should reveal whether the small dark spots are impact craters, or perhaps something more exotic such as volcanoes. The reddish color of Io has been attributed to sulfur in the salts which are believed by some to make up the surface of Io. Water frost, which occurs on the surfaces of the other Galilean satellites, is absent on Io. JPL manages and controls the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01986" onclick="window.open(this.href); return false;" title="Voir l'image PIA01986: Io - Jupiter's inner satellite sur le site de la NASA">Voir l'image PIA01986: Io - Jupiter's inner satellite sur le site de la NASA.</a></div>
PIA01986: Io - Jupiter's inner satellite
<h1>PIA01989: Io</h1><div class="PIA01989" lang="en" style="width:200px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This Voyager 2 picture of Io was taken in ultraviolet light on the evening of July 4, 1979, at a range of 4.7 million kilometers (2.9 million miles). The bright spot on the right limb is one of the volcanic eruption plumes first photographed by Voyager 1. The plume is more than 200 kilometers (124 miles) high. The volcano apparently has been erupting since it was observed by Voyager 1 in March. This suggests that the volcanos on Io probably are in continuous eruption.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01989" onclick="window.open(this.href); return false;" title="Voir l'image PIA01989: Io sur le site de la NASA">Voir l'image PIA01989: Io sur le site de la NASA.</a></div>
PIA01989: Io
<h1>PIA02201: Io</h1><div class="PIA02201" lang="en" style="width:790px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This Voyager 1 view of an equatorial region near longitude 300 degrees shows several large surface flows that originate in volcanic craters or calderas. At the right edge is a light flow about 250 kilometers long. Another dark, lobate flow with bright edges is just left of center, with an exceedingly dark caldera to its left.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02201" onclick="window.open(this.href); return false;" title="Voir l'image PIA02201: Io sur le site de la NASA">Voir l'image PIA02201: Io sur le site de la NASA.</a></div>
PIA02201: Io
<h1>PIA02231: Io - high resolution</h1><div class="PIA02231" lang="en" style="width:720px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture of Io was taken by Voyager 1 on the morning of March 5, 1979 at a range of about 92,000 km (55,000 mi.). The view is of the terminator region centered at 60 degrees south latitude and 276 degrees longitude. North is toward the upper left-hand corner of the picture. The Sun is shining from lower-left to upper-left. Shadows cast by cliffs are clearly visible near the terminator. The long valley which parallels the terminator is about 300 km long and 50 km wide. It may be a fault trough due to crustal deformation. Other cliffs which parallel the trough may also be faults. The large bright patch in the lower left portion of the picture, and the two black spots are probably some type of surface deposits. The Voyager Project is managed and controlled by the Jet Propulsion Laboratory for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02231" onclick="window.open(this.href); return false;" title="Voir l'image PIA02231: Io - high resolution sur le site de la NASA">Voir l'image PIA02231: Io - high resolution sur le site de la NASA.</a></div>
PIA02231: Io - high resolution
<h1>PIA02232: Io - high res limb</h1><div class="PIA02232" lang="en" style="width:794px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture of Io was taken on the morning of March 5 at a rang eof 75,445 kilometers. The area shown is at latitude 15 south longitude 244 . Many depressions and elevations are shown. The light is coming from the left, so a depression has a bright right wall and shadow on the left wall. The depressions are complex in shape and do not resemble impact craters. Two of the depressions are joined by a shallow trough. The elevations are irregular and comical. They are cut by linear and irregular troughs. The surface is smooth and plain-like, that is, the surface is not pockmarked by abundant impact craters so are probably geologically young. The Voyager Project is managed and controlled by the Jet Propulsion Laboratory for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02232" onclick="window.open(this.href); return false;" title="Voir l'image PIA02232: Io - high res limb sur le site de la NASA">Voir l'image PIA02232: Io - high res limb sur le site de la NASA.</a></div>
PIA02232: Io - high res limb
<h1>PIA02248: Io</h1><div class="PIA02248" lang="en" style="width:795px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This photo of Io, innermost of the four large Galilean satellites of Jupiter, was taken through an ultraviolet filter by the narrow angle camera of Voyager 1. The photo was taken at 2 a.m. (PST) Feb. 27, when Voyager 1 was 4.3 million miles (7 million kilometers) from Io, seen against the background of a part of Jupiter's disk. North is at the top, and the central longitude of Io is 180 degrees. Io shows a contrasting surface, with generally very dark polar areas and numerous light and dark regions around the equator. At this resolution (about 100 miles or 160 kilometers), no topographic features, such as craters, can be seen. The brighter regions are believed to contain sulfur and various salts, making Io highly reflective (about six times brighter than Earth's Moon) in visible and enhanced light. This satellite of Jupiter has almost exactly the same size and density as our own Moon, but it apparently has followed a very different evolutionary path, influenced by its proximity to Jupiter and the intense bombardment it receives from the Jovian radiation belts of energetic charged particles. JPL manages and controls the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02248" onclick="window.open(this.href); return false;" title="Voir l'image PIA02248: Io sur le site de la NASA">Voir l'image PIA02248: Io sur le site de la NASA.</a></div>
PIA02248: Io
<h1>PIA02249: Io - south pole</h1><div class="PIA02249" lang="en" style="width:796px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This image was acquired by Voyager 1 as it approached close passage by the south pole of Io, the innermost of the four large Galilean satellites. This image was acquired at a range of 82,500 kilometers and shows an area approximately 600 km (350 miles) on a side. The sun shines from the left about 45 above the horizon as seen from the surface. The region shown is in Io's equatorial region and contains a myriad of complex features. A variety of features are visible: mountain and plateaus bounded by scarps that vary from irregular to linear, vast smooth plains, rough bright areas that may evidence curious erosion. The Voyager Project is managed and controlled by the Jet Propulsion Laboratory for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02249" onclick="window.open(this.href); return false;" title="Voir l'image PIA02249: Io - south pole sur le site de la NASA">Voir l'image PIA02249: Io - south pole sur le site de la NASA.</a></div>
PIA02249: Io - south pole
<h1>PIA02250: Io - southern hemisphere</h1><div class="PIA02250" lang="en" style="width:790px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture of part of the southern hemisphere of Io was taken at a range of 74,675 km and shows an area at the terminator, very close to the edge of the disk as viewed from the spacecraft. In the foreground is gently undulating topography, while in the back-ground are two mountains with their near faces brightly illuminated by the sun. The mountain in the right is approximately 150 km across at its base and its height is probably in excess of 15 km which would make it higher than any mountain on Earth. The origin of the feature is not known but it could be a large volcano. In the foreground are numerous irregular markings which are typical of much of the surface of Io seen so far. The Voyager Project is managed and controlled by the Jet Propulsion Laboratory for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02250" onclick="window.open(this.href); return false;" title="Voir l'image PIA02250: Io - southern hemisphere sur le site de la NASA">Voir l'image PIA02250: Io - southern hemisphere sur le site de la NASA.</a></div>
PIA02250: Io - southern hemisphere
<h1>PIA02254: Io - crescent with plumes</h1><div class="PIA02254" lang="en" style="width:505px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Voyager 2 took this picture of Io July 10, 1979, from a range of 1.2 million kilometers (750,000 miles). It was one of the last of an extensive sequence of "volcano watch" pictures planned as a time lapse study of the nearest of Jupiter's Galilean satellites. The sunlit crescent of Io is seen at the left, and the night side illuminated by light reflected from Jupiter can also be seen. Three volcanic eruption plumes are visible on the limb. All three were previously seen by Voyager 1. On the bright limb Plume 5 (upper) and Plume 6 (lower) are about 100 kilometers high, while Plume 2 on the dark limb is about 185 kilometers high and 325 kilometers wide. The dimensions of Plume 2 are about 1 1/2 times greater than during the Voyager 1 encounter, indicating that the intensity of the eruptions has increased during the four-month time interval between the Voyager encounters. The three volcanic eruptions and at least three others have apparently been active at roughly the same intensity or greater for a period of at least four months.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02254" onclick="window.open(this.href); return false;" title="Voir l'image PIA02254: Io - crescent with plumes sur le site de la NASA">Voir l'image PIA02254: Io - crescent with plumes sur le site de la NASA.</a></div>
PIA02254: Io - crescent with plumes
<h1>PIA02280: Io</h1><div class="PIA02280" lang="en" style="width:765px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture of Io, Jupiter's innermost Galilean satellite, was taken by Voyager 1 on the morning of March 5, 1979, during the closest approach to this satellite. The picture was recorded on the onboard tape recorder and then sent back to Earth on the morning of March 7, 1979. Voyager 1 was at a range of 30,800 km (18,480 mi) from Io when the picture was taken. This region of Io is centered at 67 degrees south latitude and 328 degrees longitude. The picture width is about 246 km (147 mi). The smallest features visible are about 0.3 km (0.2 mi) across. The picture shows an irregularly shaped composite crater about 50 km (30 mi) in diameter with dark flows radiating from its rim. The crater is a volcanic caldera and the dark flows are probably low viscosity lavas possibly of basaltic composition. Some of the lava flows are over 100 km long and 15 km wide. Similar but smaller flows and craters occur on the island of Hawaii. JPL manages and controls the Voyager Project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02280" onclick="window.open(this.href); return false;" title="Voir l'image PIA02280: Io sur le site de la NASA">Voir l'image PIA02280: Io sur le site de la NASA.</a></div>
PIA02280: Io
<h1>PIA02287: Io Pele plume</h1><div class="PIA02287" lang="en" style="width:430px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Voyager 1 took this narrow-angle camera image on 5 March 1979 from a distance of 450,000 kilometers. At this geometry, the camera looks straight down through a volcanic plume at one of Io's most active volcanos, Pele. The large heart-shaped feature is the region where Pele's plume falls to the surface. At the center of the "heart" is the small dark fissure that is the source of the eruption. The Voyager Project is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02287" onclick="window.open(this.href); return false;" title="Voir l'image PIA02287: Io Pele plume sur le site de la NASA">Voir l'image PIA02287: Io Pele plume sur le site de la NASA.</a></div>
PIA02287: Io Pele plume
<h1>PIA02288: Io Caldera</h1><div class="PIA02288" lang="en" style="width:420px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Voyager 1 took this narrow-angle camera image on 5 March 1979 from a distance of 69,000 kilometers. The feature shown is a volcanic caldera which may be actively spewing material into space (dark gray fuzz near the upper-right part of the caldera rim). In addition, very dark lava has flowed out of the fissure and spread on the floor of the caldera. The Voyager Project is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02288" onclick="window.open(this.href); return false;" title="Voir l'image PIA02288: Io Caldera sur le site de la NASA">Voir l'image PIA02288: Io Caldera sur le site de la NASA.</a></div>
PIA02288: Io Caldera
<h1>PIA02294: Io 2x2 Mosaic</h1><div class="PIA02294" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Perhaps the most spectacular of all the Voyager photos of Io is this mosaic obtained by Voyager 1 on March 5 at a range of 400,000 kilometers. A great variety of color and albedo is seen on the surface, now thought to be the result of surface deposits of various forms of sulfur and sulfur dioxide. The two great volcanoes Pele and Loki (upper left) are prominent.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA02294" onclick="window.open(this.href); return false;" title="Voir l'image PIA02294: Io 2x2 Mosaic sur le site de la NASA">Voir l'image PIA02294: Io 2x2 Mosaic sur le site de la NASA.</a></div>
PIA02294: Io 2x2 Mosaic
<h1>PIA02308: Global image of Io (true color)</h1><div class="PIA02308" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>NASA's Galileo spacecraft acquired its highest resolution images of Jupiter's moon Io on 3 July 1999 during its closest pass to Io since orbit insertion in late 1995. This color mosaic uses the near-infrared, green and violet filters (slightly more than the visible range) of the spacecraft's camera and approximates what the human eye would see. Most of Io's surface has pastel colors, punctuated by black, brown, green, orange, and red units near the active volcanic centers. <a href="/catalog/PIA02309">A false color version</a> of the mosaic has been created to enhance the contrast of the color variations.</p><p>The improved resolution reveals small-scale color units which had not been recognized previously and which suggest that the lavas and sulfurous deposits are composed of complex mixtures (Cutout A of false color image). Some of the bright (whitish), high-latitude (near the top and bottom) deposits have an ethereal quality like a transparent covering of frost (Cutout B of false color image). Bright red areas were seen previously only as diffuse deposits. However, they are now seen to exist as both diffuse deposits and sharp linear features like fissures (Cutout C of false color image). Some volcanic centers have bright and colorful flows, perhaps due to flows of sulfur rather than silicate lava (Cutout D of false color image). In this region bright, white material can also be seen to emanate from linear rifts and cliffs.</p><p>Comparison of this image to <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>./atjup/io/color.html">previous Galileo images</a> reveals many changes due to the ongoing volcanic activity.</p><p>Galileo will make two close passes of Io beginning in October of this year. Most of the high-resolution targets for these flybys are seen on the hemisphere shown here.</p><p>North is to the top of the picture and the sun illuminates the surface from almost directly behind the spacecraft. This illumination geometry is good for imaging color variations, but poor for imaging topographic shading. However, some topographic shading can be seen here due to the combination of relatively high resolution (1.3 kilometers or 0.8 miles per picture element) and the rugged topography over parts of Io. The image is centered at 0.3 degrees north latitude and 137.5 degrees west longitude. The resolution is 1.3 kilometers (0.8 miles) per picture element. The images were taken on 3 July 1999 at a range of about 130,000 kilometers (81,000 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft during its twenty-first orbit.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at URL <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/PIA02308" onclick="window.open(this.href); return false;" title="Voir l'image PIA02308: Global image of Io (true color) sur le site de la NASA">Voir l'image PIA02308: Global image of Io (true color) sur le site de la NASA.</a></div>
PIA02308: Global image of Io (true color)
<h1>PIA02309: Global image of Io (false color)</h1><div class="PIA02309" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>NASA's Galileo spacecraft acquired its highest resolution images of Jupiter's moon Io on 3 July 1999 during its closest pass to Io since orbit insertion in late 1995. This color mosaic uses the near-infrared, green and violet filters (slightly more than the visible range) of the spacecraft's camera which have been processed to enhance more subtle color variations. Most of Io's surface has pastel colors, punctuated by black, brown, green, orange, and red units near the active volcanic centers. <a href="/catalog/PIA02308">A true color version</a> of the mosaic has been created to show how Io would appear to the human eye.</p><p>The improved resolution reveals small-scale color units which had not been recognized previously and which suggest that the lavas and sulfurous deposits are composed of complex mixtures (Cutout locations), (Cutout A). Some of the bright (whitish), high-latitude (near the top and bottom) deposits have an ethereal quality like a transparent covering of frost (Cutout B). Bright red areas were seen previously only as diffuse deposits. However, they are now seen to exist as both diffuse deposits and sharp linear features like fissures (Cutout C). Some volcanic centers have bright and colorful flows, perhaps due to flows of sulfur rather than silicate lava (Cutout D). In this region bright, white material can also be seen to emanate from linear rifts and cliffs.</p><p>Comparison of this mosaic to <a href="http://www2.jpl.nasa.gov/galileo/sepo/" target="_blank">http://www.jpl.nasa.gov/galileo/sepo</a>./atjup/io/color.html">previous Galileo images</a> reveals many changes due to the ongoing volcanic activity.</p><p>Galileo will make two close passes of Io beginning in October of this year. Most of the high-resolution targets for these flybys are seen on the hemisphere shown here.</p><p>North is to the top of the picture and the sun illuminates the surface from almost directly behind the spacecraft. This illumination geometry is good for imaging color variations, but poor for imaging topographic shading. However, some topographic shading can be seen here due to the combination of relatively high resolution (1.3 kilometers or 0.8 miles per picture element) and the rugged topography over parts of Io. The image is centered at 0.3 degrees north latitude and 137.5 degrees west longitude. The resolution is 1.3 kilometers (0.8 miles) per picture element. The images were taken on 3 July 1999 at a range of about 130,000 kilometers (81,000 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft during its twenty-first orbit.</p><p>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.</p><p>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL <a href="http://solarsystem.nasa.gov/galileo/" target="_blank">http://solarsystem.nasa.gov/galileo/</a>. Background information and educational context for the images can be found at URL <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/PIA02309" onclick="window.open(this.href); return false;" title="Voir l'image PIA02309: Global image of Io (false color) sur le site de la NASA">Voir l'image PIA02309: Global image of Io (false color) sur le site de la NASA.</a></div>
PIA02309: Global image of Io (false color)