Jupiter: the "King" and His Moons
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Io-Ionian Mountains and calderas-PIA02526.jpgIonian Mountains and Calderas on Io (real colors)73 visitenessun commento
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Io-LokiPatera-PIA00320.jpgLoki patera: an everlasting eruption...53 visiteA huge area of Io's volcanic plains is shown in this Voyager 1 image mosaic. Numerous volcanic calderas and lava flows are visible here. Loki Patera, an active lava lake, is the large shield-shaped black feature. Heat emitted from Loki can be seen through telescopes all the way from Earth. These telescopic observations tell us that Loki has been active continuously (or at least every time astronomers have looked) since the Voyager 1 flyby in March 1979. The composition of Io's volcanic plains and lava flows has not been determined, but they could consist dominantly of Sulphur (S) with surface frosts of S dioxide or of silicates (such as basalts) encrusted with S and S dioxide condensates. The bright whitish patches probably consist of freshly deposited SO2 frost. The black spots, including Loki, are probably hot sulfur lava, which may remain molten by intrusions of molten silicate magma, coming up from deeper within Io. The ultimate source of heat that keeps Io active is tidal frictional heating due to the continual flexure of Io by the gravity of Jupiter and Europa, another of Jupiter's satellites.
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Io-Loki_Patera-PIA00320-PCF-LXTT-IPF.jpgVolcanic Plains and Paterae on Io: Loki Patera (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)94 visiteA huge area of Io's Volcanic Plains is well shown in this mosaic of pictures taken by the NASA - Voyager 1 Space Probe. Numerous Volcanic Calderas and Lava Flows are visible here, including the Loki Patera (an active Lava Lake), which is the large shield-shaped and dark red Surface Feature visible in the lower right portion of the mosaic. As a matter of fact, the (sometime) intense light emitted from the Lava that boils inside Loki Patera can even be seen through telescopes, all the way from Earth, and these observations tell us that Loki has been active continuously (or at least every time an astronomer took a good look at it...) since the Voyager 1 Fly-By, which occurred in the month of March of the AD 1979.
The composition of Io's Volcanic Plains and Lava Flows has not been completely determined yet but, in the light of the information that we already possess (and, in particular, once we duly consider the orange-yellow color that can be seen over most of the Surface of Io), it is reasonable to say that they could dominantly consist of Sulphur, with Surface Frosts made of Sulphur Dioxide, Silicates (such as Basalts) encrusted with Sulphur and Sulphur Dioxide Condensates. The bright whitish patches, on the other hand, could probably consist of freshly deposited Sulphur Dioxide Frost. The dark red (and, sometime, almost black) spots, including Loki, are hot Sulphur Lava Lakes, which may remain molten even 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. However, the very ultimate source of heat that keeps Io active, must be the Tidal (Frictional) Heating, due to the perpetual flexure of Io that is caused by the powerful Gravitational Influence of both Jupiter and Europa.
This picture (which is an Original NASA - Voyager 1 Space Proble color image mosaic published on the NASA - Planetary Photojournal with the n. PIA 00320) 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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Io-Masubi plume-GAL-PIA02502_modest.jpgThe "Masubi" plume72 visiteA plume of gas and particles is ejected some 100 kilometers (about 60 miles) above the surface of Jupiter's volcanic moon Io in this color image, recently taken by NASA¹s Galileo spacecraft.
The plume is erupting from near the location of a plume first observed by the Voyager spacecraft in 1979 and named Masubi. However, during the course of the Galileo tour of Jupiter and its moons, a plume has appeared at different locations within the Masubi region.
This color image is the same as the previously released false color mosaic of Io, but with special processing to enhance the visibility of the plume. The plume appears blue because of the way small particles in the plume scatter light.
North is to the top of the picture, and the Sun illuminates the surface from almost directly behind the spacecraft. The resolution is 1.3 kilometers (0.8 miles) per picture element. The images were taken on July 3, 1999 at a distance of about 130,000 kilometers (81,000 miles) by the Galileo¹s camera.
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Io-Natural_Colors-NASA.jpgIo (True Colors - credits: Galileo Project, JPL, NASA)86 visiteCaption NASA:"The strangest moon in the Solar System is bright yellow.
This picture, an attempt to show how Io would appear in the "true colors" perceptible to the average human eye, was taken in july 1999 by the Galileo Spacecraft that orbited Jupiter from 1995 to 2003.
Io's colors derive from Sulphur and molten Silicate Rock. The unusual Surface of Io is kept very young by its system of active volcanoes. The intense tidal gravity of Jupiter stretches Io and damps wobbles caused by Jupiter's other Galilean moons.
The resulting friction greatly heats Io's interior, causing molten rock to explode through the Surface. Io's volcanoes are so active that they are effectively turning the whole moon inside out. Some of Io's volcanic lava is so hot that it glows in the dark".MareKromium
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Io-Natural_Colors-PCF-LXTT.jpgIo (Absolute Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)120 visitenessun commentoMareKromium
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Io-New_Horizons.jpgIo (HR)53 visiteCaption NASA:"Spewed from a volcano, a complex plume rises over 300 Km above the horizon of Jupiter's moon Io in this image from cameras onboard the New Horizons spacecraft. The volcano, Tvashtar, is marked by the bright glow (about 1 o'clock) at the moon's edge, beyond the terminator or night/day shadow line. The shadow of Io cuts across the plume itself. Also capturing stunning details on the dayside surface, the high resolution image was recorded when the spacecraft was 2,3 MKM from Io. Later it was combined with lower resolution color data by astro-imager Sean Walker to produce this sharp portrait of the solar system's most active moon. Outward bound at almost 23 Km-per-second, the New Horizons spacecraft should cross the orbit of Saturn in June next year, and is ultimately destined to encounter Pluto in 2015".
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Io-PIA00491.jpgIo: five views of the one and the same54 visiteFive 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.
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.
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Io-PIA00495.jpgAs Time Goes By...On Io!53 visiteVolcanoes on Jupiter's moon Io are compared in these images from Galileo spacecraft (right) taken in early September of 1997 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. 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 Km (about 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).
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Io-PIA00715.jpgIo: three views of the one and the same53 visiteThree 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.
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Io-PIA00740.jpgThe "face" of Io53 visitenessun commento
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Io-PIA01070.jpgAs Time Goes By...On Io! (1)54 visiteDetail of changes on Jupiter's moon Io in the Region around Volund as seen by the Voyager 1 spacecraft in April 1979 (left frame) and NASA's Galileo spacecraft in September 1996 (right frame). North is to the top of both frames which are approx. 600 by 600 Km. Note the new linear feature, which may be a volcanic fissure, trending east from the southern end of Volund. Dark diffuse material lies to the west and a ring of bright material which may be SO2- rich plume deposits appears to be centered near the middle of the new linear feature.
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