Jupiter: the "King" and His Moons |
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Pillan Patera23 visteThese images of Jupiter's volcanic moon, Io, show the results of a dramatic event that occurred on the fiery satellite during a five-month period. The changes, captured by the solid state imaging (CCD) system on NASA's Galileo spacecraft, occurred between the time Galileo acquired the left frame, during its seventh orbit of Jupiter, and the right frame, during its tenth orbit. A new dark spot, 400 kilometers (249 miles) in diameter, which is roughly the size of Arizona, surrounds a volcanic center named Pillan Patera. Galileo imaged a 120 kilometer (75 mile) high plume erupting from this location during its ninth orbit. Pele, which produced the larger plume deposit southwest of Pillan, also appears different than it did during the seventh orbit, perhaps due to interaction between the two large plumes. Pillan's plume deposits appear dark at all wavelengths. This color differs from the very red color associated with Pele, but is similar to the deposits of Babbar Patera, the dark feature southwest of Pele. Some apparent differences between the images are not caused by changes on Io's surface, but rather are due to differences in illumination, emission and phase angles. This is particularly apparent at Babbar Patera.
North is to the top of the images. The left frame was acquired on April 4th, 1997, while the right frame was taken on Sept. 19th, 1997. The images were obtained at ranges of 563,000 kilometers (350,000 miles) for the left image, and 505,600 kilometers (314,165 miles) for the right.
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Pele's deposits on Io34 visteThe varied effects of Ionian volcanism can be seen in this false color infrared composite image of Io's Trailing Hemisphere. LR color data from Galileo's first orbit (June, 1996) have been combined with a HR clear filter picture taken on the third orbit (November, 1996) of the spacecraft around Jupiter. A diffuse ring of bright red material encircles Pele, the site of an ongoing, high velocity volcanic eruption. Pele's plume is nearly invisible, except in back-lit photographs, but its deposits indicate energetic ejection of sulfurous materials out to distances more than 600 Km from the central vent. Another bright red deposit lies adjacent to Marduk, also a currently active ediface. High temperature hot spots have been detected at both these locations, due to the eruption of molten material in lava flows or lava lakes. Bright red deposits on Io darken and disappear within years or decades of deposition, so the presence of bright red materials marks the sites of recent volcanism.
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Old impact crater on Europa (from about 29.000 Km)32 visteThis feature on Europa was seen as a dark, diffuse circular patch on a previous Galileo global image of Europa's Leading Hemisphere on April 3, 1997. The "bulls-eye" pattern appears to be a 140- Km-wide impact scar (about the size of the island of Hawaii) which formed as the surface fractured minutes after a mountain-sized asteroid or comet slammed into the satellite. This approx. 214-Km-wide picture is the product of 3 images which have been processed in false color to enhance shapes and compositions. North is toward the top of this picture, which is illuminated from sunlight coming from the West. This color composite reveals a sequence of events which have modified the surface of Europa. The earliest event was the impact which formed the Tyre structure at 34° North Latitude and 146,5° West Longitude. The impact was followed by the formation of the reddish lines superposed on Tyre. The red color designates areas that are probably a dirty water ice mixture. The fine blue-green lines crossing the region from west to east appear to be ridges which formed after the crater.
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Mountains on Io (MULTISPECTRUM; credits: Lunexit)13 visteCaption NASA:"This image taken by NASA's Galileo Spacecraft during its close flyby of Jupiter's moon Io on November 25, 1999 shows some of the curious mountains found there. The Sun is illuminating the scene from the left, and because it is setting, the Sun exaggerates the shadows cast by the mountains. By measuring the lengths of these shadows, Galileo scientists can estimate the height of the mountains. The mountain just left of the middle of the picture is 4 Km (13.000 feet) high and the small peak to the lower left is 1,6 Km (5000 feet) high.
These mountains, like others imaged during a previous Galileo flyby of Io in October '99, seem to be in the process of collapsing. Huge landslides have left piles of debris at the bases of the mountains. The ridges that parallel their margins are also indicative of material moving down the mountainsides due to gravity.
North is to the upper left of the picture. The image, centered at 8,1° South Latitude and 78,7° East Longitude, covers an area approx. 210-by-110 Km (such as about 130-by-70 miles). The resolution is 267 meters (880 feet) per picture element.
The image was taken at a range of approx. 25.000 Km (about 16.000 miles) by Galileo's onboard camera".
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More "Plumes" on Io31 vistenessun commento
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Moments of the "Red Spot" - HST48 vistenessun commento
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Moments of Tvashtar (3)58 vistenessun commento
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Moments of Tvashtar (2)81 vistenessun commento
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Moments of Tvashtar (1)67 vistenessun commento
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Metis (Natural Colors; credits: Ted Stryk)13 visteMetis, o Metide, è il più interno fra i Satelliti Naturali di Giove. Appartiene al cosiddetto gruppo di Amaltea, che si compone dei piccoli satelliti interni del Pianeta. Il suo nome storico è Giove XVI.
La scoperta di Metis risale al 1979, quando fu individuato grazie alle immagini inviate a Terra dalla sonda spaziale statunitense Voyager 1 e gli venne attribuito il nome provvisorio S/1979 J3; nel 1983 l'Unione Astronomica Internazionale lo battezzò ufficialmente con il nome della titanide Metide, prima moglie di Zeus e madre di Atena secondo la Mitologia Greca.
Il colorito giallo-rossastro che è stato attribuito a questo Corpo Celeste da Ted Stryk potrebbe trovare una giustificazione negli accumuli (depositi superficiali) di Zolfo che Metis - periodicamente - "raccoglie" dallo Spazio durante i suoi passaggi ravvicinati ad Io.
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Look at Me!31 visteWhen 17th-century astronomers first turned their telescopes to Jupiter, they noted a conspicuous reddish spot on the Giant Planet. This Great Red Spot is still present in Jupiter's atmosphere, more than 300 years later. It is now known that it is a vast storm, spinning like a cyclone. Unlike a low-pressure hurricane in the Caribbean Sea, however, the Red Spot rotates in a counterclockwise direction in the Southern Hemisphere, showing that it is a high-pressure system. Winds inside this Jovian storm reach speeds of about 270 mph.
The Red Spot is the largest known storm in the Solar System. With a diameter of about 15.400 miles, it is almost twice the size of the entire Earth and 1/6th the diameter of Jupiter itself.
The long lifetime of the Red Spot may be due to the fact that Jupiter is mainly a gaseous planet. It possibly has liquid layers, but lacks a solid surface, which would dissipate the storm's energy, much as happens when a hurricane makes landfall on the Earth. However, the Red Spot does change its shape, size, and color, sometimes dramatically. Such changes are demonstrated in high-resolution Wide Field and Planetary Cameras 1 & 2 images of Jupiter obtained by NASA's Hubble Space Telescope between 1992 and 1999(PIA01594 thru PIA01599 and PIA02400 thru PIA02402). This image was obtained in April 1997.
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Loki's eruption on Io (the "Plume")48 visteUn'informazione importante per chi volesse provare a calcolare le dimensioni effettive della "piuma vulcanica" (conoscendo, ovviamente, le dimensioni di Io): l'immagine è stata scattata da (circa) 490.000 Km.
Original caption:"Voyager 1 image of Io showing active plume of Loki on limb. Heart-shaped feature southeast of Loki consists of fallout deposits from active plume Pele. The images that make up this mosaic were taken from an average distance of approximately 490.000 Km (about 340.000 miles)".
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