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

<h1>PIA09665: Tvashtar in Motion</h1><div class="PIA09665" lang="en" style="width:512px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This five-frame sequence of New Horizons images captures the giant plume from Io's Tvashtar volcano. Snapped by the probe's Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Jupiter earlier this year, this first-ever "movie" of an Io plume clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 miles) above the moon's surface. Only the upper part of the plume is visible from this vantage point -- the plume's source is 130 kilometers (80 miles) below the edge of Io's disk, on the far side of the moon.</p><p>The appearance and motion of the plume is remarkably similar to an ornamental fountain on Earth, replicated on a gigantic scale. The knots and filaments that allow us to track the plume's motion are still mysterious, but this movie is likely to help scientists understand their origin, as well as provide unique information on the plume dynamics.</p><p>Io's hyperactive nature is emphasized by the fact that two other volcanic plumes are also visible off the edge of Io's disk: Masubi at the 7 o'clock position, and a very faint plume, possibly from the volcano Zal, at the 10 o'clock position. Jupiter illuminates the night side of Io, and the most prominent feature visible on the disk is the dark horseshoe shape of the volcano Loki, likely an enormous lava lake. Boosaule Mons, which at 18 kilometers (11 miles) is the highest mountain on Io and one of the highest mountains in the solar system, pokes above the edge of the disk on the right side. </p><p>The five images were obtained over an 8-minute span, with two minutes between frames, from 23:50 to 23:58 Universal Time on March 1, 2007. Io was 3.8 million kilometers (2.4 million miles) from New Horizons; the image is centered at Io coordinates 0 degrees north, 342 degrees west. </p><p>The pictures were part of a sequence designed to look at Jupiter's rings, but planners included Io in the sequence because the moon was passing behind Jupiter's rings at the time.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA09665" onclick="window.open(this.href); return false;" title="Voir l'image PIA09665: Tvashtar in Motion sur le site de la NASA">Voir l'image PIA09665: Tvashtar in Motion sur le site de la NASA.</a></div>
PIA09665: Tvashtar in Motion
<h1>PIA10099: Changes on Io</h1><div class="PIA10099" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>A: A global map of Jupiter's moon Io derived from eight images taken by the Long Range Reconnaissance Imager (LORRI) on the New Horizons spacecraft, as it passed Jupiter on its way to Pluto in late February 2007. Details as small as 12 kilometers (7 miles) are visible. The map shows the comprehensive picture of Io's volcanism obtained by New Horizons. Yellow ovals denote areas with new, faded or shifted plume deposits since the last images taken by the Galileo spacecraft in 2001. Green circles denote areas where probable new lava flows have occurred. Cyan diamonds indicate locations of active volcanic plumes, and orange hexagons are volcanic hot spots detected by the Linear Etalon Imaging Spectral Array (LEISA) instrument. For plumes and hot spots, symbol size indicates the approximate relative size and brightness of the features. </p><p>B-F: Comparison of New Horizons (NH) and earlier images of major surface changes discovered by New Horizons at Io's volcanoes Masubi (45 degrees S, 57 degrees West) and North Lerna (55 degrees S, 290 degrees W). The scale bars are 200 kilometers long, and a is the solar phase angle. At Masubi, old lava flows seen by Voyager and Galileo (B) have been obscured at low phase angles (C) by deposits from two active plumes associated with a new 240-kilometer (150-mile) long dark lava flow, which is the longest lava flow known to have been erupted in the solar system since the discovery of Io volcanism in 1979. At North Lerna, a recent eruption has generated a 130-km long lava flow (F), as well as an active plume that has produced a concentric pattern of deposits. </p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA10099" onclick="window.open(this.href); return false;" title="Voir l'image PIA10099: Changes on Io sur le site de la NASA">Voir l'image PIA10099: Changes on Io sur le site de la NASA.</a></div>
PIA10099: Changes on Io
<h1>PIA10100: Io Eclipse Montage</h1><div class="PIA10100" lang="en" style="width:610px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>New Horizons took this montage of images of Jupiter's volcanic moon Io, glowing in the dark of Jupiter's shadow, as the Pluto-bound spacecraft sped through the Jupiter system on Feb. 27, 2007. </p><p>(A): In this picture from the Long-Range Reconnaissance Imager (LORRI), dark blotches and straight lines are artifacts. The brightest spots (including the volcanoes Pele [P] and East Girru [EG]) are incandescent lava from active volcanoes. The more diffuse glows, and the many faint spots, are from gas in the plumes and atmosphere, glowing due to bombardment by plasma in Jupiter's magnetosphere, in a display similar to the Earth's aurorae. (B): The same image with a latitude/longitude grid, showing that the cluster of faint spots is centered near longitude 0 degrees, the point on Io that faces Jupiter. The image also shows the locations of the plumes seen in sunlit images (indicated by red diamonds), which glow with auroral emission in eclipse. (C): Simulated sunlit view of Io with the same geometry, based on sunlit LORRI images. (D): A combination of the sunlit image (in cyan) and the eclipse image (in red), showing that all point-like glows in the eclipse image arise from dark volcanoes in the eclipse image. (E): This infrared image, at a wavelength of 2.3 microns, obtained by New Horizons Linear Etalon Spectral Imaging Array (LEISA) an hour after the LORRI image, showing thermal emission from active volcanoes. Elongation of the hot spots is an artifact. (F): Combined visible albedo (cyan) and LEISA thermal emission (red) image, showing the sources of the volcanic emission. That most of the faint point-like glows near longitude zero, seen in visible light in images A, B, and D, do not appear in the infrared view of volcanic heat radiation, is one reason scientists believe that these glows are due to auroral emission, not heat radiation.</p><p>This image appears in the Oct. 12, 2007, issue of Science magazine, in a paper by John Spencer, et al. </p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA10100" onclick="window.open(this.href); return false;" title="Voir l'image PIA10100: Io Eclipse Montage sur le site de la NASA">Voir l'image PIA10100: Io Eclipse Montage sur le site de la NASA.</a></div>
PIA10100: Io Eclipse Montage
<h1>PIA10101: Tvashtar Montage</h1><div class="PIA10101" lang="en" style="width:504px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The Tvashtar plume on Io, seen by the Hubble Space Telescope (HST) and by New Horizons. </p><p>(A): The image in which the plume was discovered, taken by HST in ultraviolet light on Feb. 14, 2007, at a wavelength of 260 nm. The red diamond indicates location of the Tvashtar hot spot seen later by New Horizons. (B): An HST image of Io and the Tvashtar plume seen against Jupiter; sulfur gas in the plume absorbs ultraviolet light, making the plume look reddish in this color composite. The composite is composed of images taken at 260 nm (blue), 330 nm (green), and 410 nm (red). Other images in this montage are in visible light from the Long-Range Reconnaissance Imager (LORRI). The scale bar is 200 kilometers long and the yellow star indicates the projected location of the hot spot at the Tvashtar plume source. The dashed line is the terminator, the line dividing day from night on Io. (C): The highest-resolution view of the full plume, at a resolution of 12.4 kilometers (7.7 miles) per pixel and a solar phase angle of 102 degrees, showing the complex filamentary structure of the plume. The images are sharpened by un-sharp masking; the dark line at the edge of the disk is an artifact of this sharpening. (D): An image at 145-degree phase angle at 22.4 kilometers (13.8 miles) per pixel, showing the time variability of the details of the plume structure and its persistent bright top. (F-J): Sequence of frames at 2-minute intervals showing dynamics in the upper part of the plume (the source is on the far side of Io). Colored diamonds track individual features whose speeds, projected on the plane of the sky, are shown in (E).</p><p>This image appears in the Oct. 12, 2007, issue of Science magazine, in a paper by John Spencer, et al. </p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA10101" onclick="window.open(this.href); return false;" title="Voir l'image PIA10101: Tvashtar Montage sur le site de la NASA">Voir l'image PIA10101: Tvashtar Montage sur le site de la NASA.</a></div>
PIA10101: Tvashtar Montage
<h1>PIA10102: Jupiter-Io Montage</h1><div class="PIA10102" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This is a montage of New Horizons images of Jupiter and its volcanic moon Io, taken during the spacecraft's Jupiter flyby in early 2007. The Jupiter image is an infrared color composite taken by the spacecraft's near-infrared imaging spectrometer, the Linear Etalon Imaging Spectral Array (LEISA) at 1:40 UT on Feb. 28, 2007. The infrared wavelengths used (red: 1.59 µm, green: 1.94 µm, blue: 1.85 µm) highlight variations in the altitude of the Jovian cloud tops, with blue denoting high-altitude clouds and hazes, and red indicating deeper clouds. The prominent bluish-white oval is the Great Red Spot. The observation was made at a solar phase angle of 75 degrees but has been projected onto a crescent to remove distortion caused by Jupiter's rotation during the scan. The Io image, taken at 00:25 UT on March 1st 2007, is an approximately true-color composite taken by the panchromatic Long-Range Reconnaissance Imager (LORRI), with color information provided by the 0.5 µm ("blue") and 0.9 µm ("methane") channels of the Multispectral Visible Imaging Camera (MVIC). The image shows a major eruption in progress on Io's night side, at the northern volcano Tvashtar. Incandescent lava glows red beneath a 330-kilometer high volcanic plume, whose uppermost portions are illuminated by sunlight. The plume appears blue due to scattering of light by small particles in the plume</p><p>This montage appears on the cover of the Oct. 12, 2007, issue of Science magazine.</p><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA10102" onclick="window.open(this.href); return false;" title="Voir l'image PIA10102: Jupiter-Io Montage sur le site de la NASA">Voir l'image PIA10102: Jupiter-Io Montage sur le site de la NASA.</a></div>
PIA10102: Jupiter-Io Montage
<h1>PIA10103: Io and Europa Meet Again</h1><div class="PIA10103" lang="en" style="width:599px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This beautiful image of the crescents of volcanic Io and more sedate Europa is a combination of two New Horizons images taken March 2, 2007, about two days after New Horizons made its closest approach to Jupiter. A lower-resolution color image snapped by the Multispectral Visual Imaging Camera (MVIC) at 10:34 universal time (UT) has been merged with a higher-resolution black-and-white image taken by the Long Range Reconnaissance Imager (LORRI) at 10:23 UT. The composite image shows the relative positions of Io and Europa, which were moving past each other during the image sequence, as they were at the time the LORRI image was taken.</p><p>This image was taken from a range of 4.6 million kilometers (2.8 million miles) from Io and 3.8 million kilometers (2.4 million miles) from Europa. Although the moons appear close together in this view, a gulf of 790,000 kilometers (490,000 miles) separates them. Io's night side is lit up by light reflected from Jupiter, which is off the frame to the right. Europa's night side is dark, in contrast to Io, because this side of Europa faces away from Jupiter.</p><p>Here Io steals the show with its beautiful display of volcanic activity. Three volcanic plumes are visible. Most conspicuous is the enormous 300-kilometer (190-mile) high plume from the Tvashtar volcano at the 11 o'clock position on Io's disk. Two much smaller plumes are also visible: that from the volcano Prometheus, at the 9 o'clock position on the edge of Io's disk, and from the volcano Amirani, seen between Prometheus and Tvashtar along Io's terminator (the line dividing day and night). The Tvashtar plume appears blue because of the scattering of light by tiny dust particles ejected by the volcanoes, similar to the blue appearance of smoke. In addition, the contrasting red glow of hot lava can be seen at the source of the Tvashtar plume.</p><p>The images are centered at 1 degree North, 60 degrees West on Io, and 0 degrees North, 149 degrees West on Europa. The color in this image was generated using individual MVIC images at wavelengths of 480, 620 and 850 nanometers. The human eye is sensitive to slightly shorter wavelengths, from 400 to 700 nanometers, and thus would see the scene slightly differently. For instance, while the eye would notice the difference between the yellow and reddish brown colors of Io's surface and the paler color of Europa, the two worlds appear very similar in color to MVIC's longer-wavelength vision. The night side of Io appears greenish compared to the day side, because methane in Jupiter's atmosphere absorbs 850 nanometer light and makes Jupiter-light green to MVIC's eyes.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA10103" onclick="window.open(this.href); return false;" title="Voir l'image PIA10103: Io and Europa Meet Again sur le site de la NASA">Voir l'image PIA10103: Io and Europa Meet Again sur le site de la NASA.</a></div>
PIA10103: Io and Europa Meet Again
<h1>PIA10249: Seeing Red</h1><div class="PIA10249" lang="en" style="width:600px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This New Horizons image of Jupiter's volcanic moon Io was taken at 13:05 Universal Time during the spacecraft's Jupiter flyby on February 28, 2007. It shows the reddish color of the deposits from the giant volcanic eruption at the volcano Tvashtar, near the top of the sunlit crescent, as well as the bluish plume itself and the orange glow of the hot lava at its source. The relatively unprocessed image on the left provides the best view of the volcanic glow and the plume deposits, while the version on the right has been brightened to show the much fainter plume, and the Jupiter-lit night side of Io.</p><p>New Horizons' color imaging of Io's sunlit side was generally overexposed because the spacecraft's color camera, the super-sensitive Multispectral Visible Imaging Camera (MVIC), was designed for the much dimmer illumination at Pluto. However, two of MVIC's four color filters, the blue and "methane" filter (a special filter designed to map methane frost on the surface of Pluto at an infrared wavelength of 0.89 microns), are less sensitive than the others, and thus obtained some well-exposed views of the surface when illumination conditions were favorable. Because only two color filters are used, rather than the usual three, and because one filter uses infrared light, the color is only a rough approximation to what the human eye would see.</p><p>The red color of the Tvashtar plume fallout is typical of Io's largest volcanic plumes, including the previous eruption of Tvashtar seen by the Galileo and Cassini spacecraft in 2000, and the long-lived Pele plume on the opposite side of Io. The color likely results from the creation of reddish three-atom and four-atom sulfur molecules (S3 and S4) from plume gases rich in two-atom sulfur molecules (S2 After a few months or years, the S3 and S4 molecules recombine into the more stable and familiar yellowish form of sulfur consisting of eight-atom molecules (S8), so these red deposits are only seen around recently-active Io volcanos. Though the plume deposits are red, the plume itself is blue, because it is composed of very tiny particles that preferentially scatter blue light, like smoke. Also faintly visible in the left image is the pale-colored Prometheus plume, almost on the edge of the disk on the equator at the 9 o'clock position.</p><p>Io was 2.4 million kilometers from the spacecraft when the picture was taken, and the center of Io's disk is at 77 degrees West longitude, 5 degrees South latitude. The solar phase angle was 107 degrees.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA10249" onclick="window.open(this.href); return false;" title="Voir l'image PIA10249: Seeing Red sur le site de la NASA">Voir l'image PIA10249: Seeing Red sur le site de la NASA.</a></div>
PIA10249: Seeing Red
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Synthese_Io.jpg