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Jupiter: the "King" and His Moons
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Io-100907_8.jpgIo: Global Map (false colors)53 visiteA: A global map of Jupiter’s moon Io derived from 8 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 Km (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.
B-F: Comparison of New Horizons (NH) and earlier images of major surface changes discovered by New Horizons at Io’s volcanoes Masubi (45° South, 57° West) and North Lerna (55° South, 290° West). The scale bars are 200 Km 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-Km (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.
This image appears in the Oct. 12, 2007, issue of Science magazine, in a paper by John Spencer, et al.MareKromium
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Io-Chain of Craters-PIA02566.jpgA chain of craters and "paterae" on Io53 visiteThis mosaic illustrates the range of "patera" morphology on Io.
But what is a "patera"? It is an irregular depression, or a complex one with scalloped edges, but which does not have the characteristics of an impact crater. The "paterae" on Io often correspond to active volcanic centers and are in some ways similar to calderas. What's a "caldera"? "Calderas" are large, usually roughly circular depressions that form by collapse over shallow magma chambers that have been partially emptied by volcanic eruptions. However, the "paterae" on Io are different from "calderas" seen elsewhere in the Solar System. They have many straight edges and sharp angles, suggesting that they are related to fractures in Io's crust. In many cases the lava can be seen to erupt from these straight edges. Planetary geologists aren't sure whether the paterae form over magma chambers or if they result from fractures and movements in the crust, and the lava subsequently follows the fractures.
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Io-Culann Tohill Patera-PIA03885_modest.jpgCulann-Tohill Patera53 visiteRepeated flybys of Io by NASA's Galileo spacecraft have allowed scientists to develop an understanding of Io's Tohil-Culann region of interconnected volcanoes and mountains.
An active volcano named Culann Patera (top center) is one of the most colorful volcanoes on Jupiter's innermost large moon (see PIA02535). It lies just north of an enigmatic mountain called Tohil Mons (see PIA03600). This mosaic image uses high-resolution Galileo images of Culann (200 meters or 660 feet per picture element) from the November 1999 flyby and high-resolution images of Tohil (165 meters or 540 feet per picture element) from the February 2000 flyby, and combines them with lower-resolution color images (1.4 kilometers or 0.9 mile per picture element) taken during the July 1999 flyby. Using the combined information, Galileo scientists have identified relationships among many colorful features in this complex.
The volcano Culann has produced both dark black and dark red lava flows, as well as diffuse, inner and outer rings of red and yellowish sulfur particles from explosive plumes (for example, PIA02502). Molten silicate rock inside Culann must occasionally mix with subsurface reservoirs of sulfur and sulfur dioxide to produce the plume deposits. The green color at the center of Culann and inside the older volcano Tohil Patera (center right) forms when red sulfur plume deposits land on dark black silicate lava flows and form a green veneer. The large white patch in southwestern Tohil Patera is rich in sulfur dioxide, and comparison with higher-resolution views (for example, PIA03527) suggests that this might be a region of cold sulfur dioxide flows. The small white patches on the mountain Tohil Mons might be deposits of sulfur dioxide snow that accumulate in grooves and at the bases of steep slopes in colder areas on the mountain. At upper right is a global view of Io showing the location of the mosaic.
Although Tohil Mons rises up to 6 kilometers (19,700 feet) above Io's plains, it is difficult to see in this image because the Sun was behind Galileo at the time it was taken. The topography of the mountainous region is clearer in a mosaic of images taken when the Sun was low in the sky, with illumination from the right (see figure below) The side-lit mosaic combines a high-resolution (330 meters or 1,100 feet per picture element) image from October 2001 with lower-resolution color images (1.4 kilometers or 0.9 mile per picture element) from July 1999.
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Io-Emakong patera-PIA02598_modest.jpgThe "Emakong" Patera (HR)58 visiteCaption NASA originale:"Clues about how lava spreads great distances on Jupiter's volcanic moon Io come from HR views taken by NASA's Galileo spacecraft of a lava channel flowing out of Emakong Patera near Io's equator.
The lava channel is dark and runs to the right from the dark patera, or large depression, at the left of this mosaic. The 1999 images showed a dark channel though which molten material once fed a broad, bright lava flow that extended for hundreds of Km".
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Io-Eruption on Tvashtar Catena-PIA02584_modest.jpgIo: eruption in Tvashtar Catena81 visiteThis pair of images taken by NASA's Galileo spacecraft captures a dynamic eruption at Tvashtar Catena, a chain of volcanic bowls on Jupiter's moon Io. They show a change in the location of hot lava over a period of a few months in 1999 and early 2000.
The image on the left uses data obtained on Nov. 26 and July 3, 1999, at resolutions of 183 meters (600 feet) and 1.3 kilometers (0.8 miles) per pixel, respectively. The red and yellow lava flow itself is an illustration based upon imaging data. The image on the right is a composite using a five-color observation made on Feb. 22, 2000, at 315 meters (1030 feet) per pixel.
These are among the most fortuitous observations made by Galileo because this style of volcanism is too unpredictable and short-lived to plan to photograph.
Short-lived bursts of volcanic activity on Io had been previously detected from Earth-based observations, but interpreting the style of volcanic activity from those lower-resolution views was highly speculative. These Galileo observations confirm hypotheses that the initial, intense thermal output comes from active lava fountains. Galileo's high-resolution observations of volcanic activity on Io have also confirmed other hypotheses based on earlier, low-resolution data. These include interpretations of slowly spreading lava flows at Prometheus and Amirani and an active lava lake at Pele. These tests of earlier hypotheses increase scientists' confidence in interpreting volcanic activity seen in low-resolution remote sensing data of Earth as well as Io. However, these data are still of insufficient resolution to adequately test the more quantitative models that have been applied to volcanic eruptions on Earth and Io.
These images also show other geologic features on Io, such as the scalloped margins of the plateau to the northeast of the active lavas. These margins appear to have formed by sapping, a process usually associated with springs of water. Liquid sulfur dioxide might be the fluid responsible for sapping on Io. A better understanding of sapping on Io will influence how scientists interpret similar features on Mars(where the viability of carbon dioxide or water as the sapping fluid remains controversial).
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Io-Eruption-PIA02545.jpgEruption on Tvashtar Catena64 visiteAn active volcanic eruption on Jupiter's moon Io was captured in this image taken on February 22, 2000 by NASA's Galileo spacecraft. Tvashtar Catena, a chain of giant volcanic calderas centered at 60 degrees north, 120 degrees west, was the location of an energetic eruption caught in action in November 1999. A dark, "L"-shaped lava flow to the left of the center in this more recent image marks the location of the November eruption. White and orange areas on the left side of the picture show newly erupted hot lava, seen in this false color image because of infrared emission. The two small bright spots are sites where molten rock is exposed to the surface at the toes of lava flows. The larger orange and yellow ribbon is a cooling lava flow that is more than more than 60 kilometers (37 miles) long. Dark, diffuse deposits surrounding the active lava flows were not there during the November 1999 flyby of Io.
This color mosaic was created by combining images taken in the near-infrared, clear, and violet filters from Galileo's camera. The range of wavelengths is slightly more than that of the human eye. The mosaic has been processed to enhance subtle color variations. The bright orange, yellow, and white areas at the left of the mosaic use images in two more infrared filters to show temperature variations, orange being the coolest and white the hottest material. This picture is about 250 kilometers (about 155 miles) across. North is toward the top and illumination from the Sun is from the west (left).
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Io-Eruption-VG1_p21286.jpgActive and Powerful Volcanic Eruption seen from Atop (Extremely Enhanced Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunar Explorer Italia)232 visitenessun commentoMareKromium
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Io-Eruptions-PIA00293.jpgContinuous eruptions on Io60 visiteThis image, taken by NASA's Galileo spacecraft, shows a new blue-colored volcanic plume extending about 100 kilometers (about 60 miles) into space from Jupiter's moon Io (see inset at lower left). The blue color of the plume is consistent with the presence of sulfur dioxide gas and 'snow' condensing from the gas as the plume expands and cools. Galileo images have also shown that the Ra Patera plume glows in the dark, perhaps due to the fluorescence of sulfur and oxygen ions created by the breaking apart of sulfur dioxide molecules by energetic particles in the Jovian magnetosphere. The images at right show a comparison of changes seen near the volcano Ra Patera since the Voyager spacecraft flybys of 1979 (windows at right show Voyager image at top and Galileo image at bottom). This eruptive plume is an example of a new type of volcanic activity discovered during Voyager's flyby in 1979, believed to be geyser-like eruptions driven by sulfur dioxide or sulfur gas erupting and freezing in Io's extremely tenuous atmosphere. Volcanic eruptions on Earth cannot throw materials to such high altitudes. Ra Patera is the site of dramatic surface changes. An area around the volcano of about 40,000 square kilometers, area about the size of New Jersey, has been covered by new volcanic deposits. The image was taken in late June 28, 1996 from a distance of 972,000 kilometers (604,000 miles).
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Io-Fire Fountain from Earth-PIA02522.jpgA "Fire Fountain" on Io...from Earth!80 visiteIl 25 Novembre 1999, dall'Osservatorio di Mauna-Kea (Hawaii), viene osservata e ripresa questa straordinaria immagine relativa ad una gigantesca "flare" (o "Fontana di Luce") occorsa su Io. Noi riteniamo che immagini come questa siano destinate ad entrare nella Storia della Scienza, ed è un peccato che a questi fenomeni i mezzi di comunicazione di massa non dedichino - praticamente - alcun rilievo. Peccato, davvero peccato...
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Io-Flares from V2-PIA01362_modest.jpgBlue flares and eruptions on the limb of crescent Io69 visiteAncora flares (di colore blu, questa volta), riprese da una distanza approssimativa di 1,2 milioni di kilometri da Io.
La ripresa, in questo caso (e si tratta comunque di un'immagine di splendida qualità e fattura), è stata effettuata dalla Sonda Voyager 2 il 9 Luglio 1979. Ci pensate? Più di 25 anni fa...
Voyager 2 took this picture of Io on the evening of July 9, 1979, from a range of 1.2 million kilometers. On the limb of Io are two blue volcanic eruption plumes about 100 kilometers high. These two plumes were first seen by Voyager 1 in March, 1979, and are designated Plume 5 (upper) and Plume 6 (lower). They have apparently been erupting for a period of at least 4 months and probably longer. A total of six plumes have been seen by Voyager 2, all of which were first seen by Voyager 1. The largest plume viewed by Voyager 1 (Plume 1) is no longer erupting. Plume 4 was not viewed on the edge of the moon's disc by Voyager 2 and therefore it is not known whether or not it is still erupting. This picture is one of a series taken to monitor the eruptions over a 6 hour period.
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Io-GalaiPatera-PIA00324.jpgGalai Patera53 visiteIo's volcanic plains are shown in this Voyager 1 image, which spans an area about 1030 km (640 miles) from left to right. North is about the 1:30 position. Numerous volcanic calderas and lava flows are visible here. The brown teardrop-shaped feature at left center is Galai Patera, a 100-km-long (62 mi) lava-flooded caldera (collapsed vent) of a volcano. The composition of Io's volcanic plains and lava flows has not been determined. The prevalent yellow, brown, and orange material may consist dominantly of sulfur with surface frosts of sulfur dioxide or of silicates (such as basalt) encrusted with sulfur and sulfur dioxide condensates. The whitish patches probably are freshly deposited SO2 frost.
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Io-Galai_Patera-PIA00324-PCF-LXTT-IPF.jpgVolcanic Plains and Paterae on Io: Galai Patera (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)104 visiteIo's Volcanic Plains and at least 9 (nine) Paterae are shown, once again, in this really beautiful and highly suggestive NASA - Voyager 1 Space Probe image, which spans an area of about 1030 Km (such as approx. 640 miles) from left to right. North is at about the 01:30 o'clock position on the frame. A number of active Volcanic Calderae and huge Lava Flows are visible here: the most important (both for size and activity) is the dark red "teardrop-shaped" Surface Feature visible near the center of the frame, slightly to the right, which is Galai Patera, an approx. 100-Km-long (such as about 62 miles) Lava-flooded Caldera (---> Collapsed Vent). As we have already mentioned in yesterday's APOD, the exact composition of Io's Volcanic Plains and Lava Flows has not been determined yet; however, the prevalent yellow, brown, and orange materials may consist, dominantly, of Sulphur, with Surface Frosts made of Sulphur Dioxide and Silicates (such as Basalt), encrusted with Sulphur and Sulphur Dioxide Condensates. The dark red (and, sometime, almost black) spots visible all around the frame, of course including Galai Patera, are hot Sulphur Lava Lakes, which may remain molten for a long time, thanks to the intrusions of molten Silicate Magma that (probably in an almost continuous way) comes up from deep inside Io. Finally, the whitish patches visible at the upper left corner, in the center and on the lower left side of the picture are, most likely, Fresh Deposits of Sulphur Dioxide Frost.
This picture (which is an Original NASA - Voyager 1 Space Proble color image mosaic published on the NASA - Planetary Photojournal with the n. PIA 00324) has been additionally processed and then re-colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Voyager 1 Space Probe and then looked outside, towards the limb of the Jovian moon Io), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team. Different colors, as well as different shades of the same color, mean, among others, the existence of different Elements present on the Surface of Io, each having a different Albedo (---> Reflectivity) and Chemical Composition.MareKromium
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