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| Piú viste - Jupiter: the "King" and His Moons |
Thebe-PIA01075.jpgThebe58 visiteOriginal caption:"These 2 images of the Jovian moon Thebe were taken by Galileo's solid state imaging system in November 1996 and June 1997, respectively. North is approximately up in both cases. Thebe, whose longest dimension is about 116 Km (or 72 miles) across, is tidally locked so that the same side of the satellite always points towards Jupiter, similar to how the nearside of our own Moon always points toward Earth. In such a tidally locked state, one side of Thebe always points in the direction in which Thebe moves as it orbits about Jupiter. This is called the "leading side" of the moon and is shown at the left. The image on the right emphasizes the side of Thebe that faces away from Jupiter (the so-called "anti-Jupiter" side). Note that there appear to be at least three or four very large impact craters on the satellite - very large in the sense that each of these craters is roughly comparable in size to the radius of Thebe".
Nota: crateri troppo grandi per un mondo così piccolo...
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Io-PIA01070.jpgAs Time Goes By...On Io! (1)58 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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Jupiter-1994-33-a-full_jpg.jpgJupiter in natural colors, after being struck by Shoemaker-Levy 958 visiteThis image of the giant planet Jupiter, by NASA's HST, reveals the impact sites of fragments "D" and "G" from Comet Shoemaker-Levy 9.
The large feature was created by the impact of fragment "G" on July 18, 1994 at 3:28 a.m. EDT. It entered Jupiter's atmosphere from the south at a 45° angle and the resulting ejecta appears to have been thrown back along that direction. The smaller feature to the left of the fragment "G" impact site was created on July 17, 1994, at 7:45 a.m. EDT by the impact of fragment "D".
This image was taken 1h and 45' after fragment "G" impacted the Planet. The "G" impact has concentric rings around it, with a central dark spot that is about 2.500 Km in diameter. Such a dark spot is surrounded by a thin, dark, ring whose diameter is roughly 7.500 Km.
Last (but not least...), the dark, thick, outermost ring's inner edge has a diameter of approx. 12.000 Km (the size of Earth...).
The impact sites are located in Jupiter Southern Hemisphere at a latitude of about 44°.
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Jupiter-PIA02865-2.JPGJupiter's clouds - 727 nnmts filter58 visiteAll the already mentined Jovian features have also been seen from ground-based telescopes, from NASA's HST and from NASA's Galileo spacecraft.
Chief among these features is the very dark patch seen in the weak methane image (619 nnmts) near the top-middle of the frame.
It is almost invisible in the next image (890 nnmts) and it appears to be composed of strands of bright clouds in this frame (727 nnmts).
This is a Region similar to the "hot spot" where the Galileo Probe entered Jupiter's atmosphere in 1995.
These images indicate that cloud cover is present at the higher altitudes but absent from the lower altitudes and this is also what the Galileo Probe found when it entered Jupiter's atmosphere.
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Jupiter-PIA01384.jpgThe Great Red Spot, from Voyager 158 visiteOriginal caption:"This view of Jupiter was taken by Voyager 1. This image was taken through color filters and recombined to produce the color image.
This photo was assembled from three black and white negatives by the Image Processing Lab at Jet Propulsion Laboratory".
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Jupiter-00.jpgJupiter (natural colors)58 visitenessun commento
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Jupiter-050107_11.jpgThe "Little Spot" of Jupiter58 visiteThis amazing color portrait of Jupiter’s “Little Red Spot” (LRS) combines high-resolution images from the New Horizons Long Range Reconnaissance Imager (LORRI), taken at 03:12 UT on February 27, 2007, with color images taken nearly simultaneously by the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope. The LORRI images provide details as fine as 9 miles across (15 Km), which is approx. 10 times better than Hubble can provide on its own.
The improved resolution is possible because New Horizons was only 1,9 MMs (about 3 MKM) away from Jupiter when LORRI snapped its pictures, while Hubble was more than 500 MMs (abou 800 MKM) away from the Gas Giant Planet.
The Little Red Spot is the second largest storm on Jupiter, roughly 70% the size of the Earth, and it started turning red in late-2005. The clouds in the Little Red Spot rotate counterclockwise, or in the anticyclonic direction, because it is a high-pressure region. In that sense, the Little Red Spot is the opposite of a hurricane on Earth, which is a low-pressure region – and, of course, the Little Red Spot is far larger than any hurricane on Earth.
Scientists don't know exactly how or why the Little Red Spot turned red, though they speculate that the change could stem from a surge of exotic compounds from deep within Jupiter, caused by an intensification of the storm system. In particular, sulfur-bearing cloud droplets might have been propelled about 50 kilometers into the upper level of ammonia clouds, where brighter sunlight bathing the cloud tops released the red-hued sulfur embedded in the droplets, causing the storm to turn red. A similar mechanism has been proposed for the Little Red Spot's "older brother," the Great Red Spot, a massive energetic storm system that has persisted for over a century.
New Horizons is providing an opportunity to examine an “infant” red storm system in detail, which may help scientists understand better how these giant weather patterns form and evolve.
MareKromium
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Himalia-lor_0035585519_0x630_sci_1-01.jpgHimalia, from New Horizons58 visiteData & Statistics for Himalia:
Discovered by: C. Perrine
Date of discovery: AD 1904
Mass (in Kg): approx. 9,56e+18
Mass (if Earth = 1): 1,5997e-06
Equatorial radius (in Km): approx. 93
Equatorial radius (if Earth = 1): 1,4581e-02
Mean density (in grm/cm^3): approx. 2,8
Mean distance from Jupiter (in Km): 11.480.000
Rotational period (in days): 0,4
Orbital period (in days): 250,5662
Mean orbital velocity (in Km/sec): 3,34
Orbital eccentricity: 0,1580
Orbital inclination: 27,63°
Escape velocity (in Km/sec): 0,117
Visual geometric albedo: 0,03
Magnitude (Vo): 14,84MareKromium
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Jupiter-HST-2008-42-a-ful-003_jpg.jpgHiding... (natural colors; credits: NASA)58 visitenessun commentoMareKromium
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Jupiter-Impact02.jpgImpact on Jupiter!58 visitenessun commentoMareKromium
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Jupiter-Impact-2010-003.jpgImpact on Jupiter! (from Hubble Space Telescope - ctx frame)58 visiteNASA scientists have interrupted the checkout and calibration of the Hubble Space Telescope to aim the recently refurbished observatory at a new expanding spot on the giant planet Jupiter. The spot, caused by the impact of a comet or an asteroid, is changing day to day in the Planet's cloud tops.
For the past several days the world's largest telescopes have been trained on Jupiter. Not to miss the potentially new science in the unfolding drama 360 MMs away, Space Telescope Science Institute director Matt Mountain allocated discretionary time to a team of astronomers led by Heidi Hammel of the Space Science Institute in Boulder, Colo.
The Hubble picture, taken on July 23, 2009, is the sharpest visible-light picture taken of the impact feature. The observations were made with Hubble's new camera, the Wide Field Camera 3 (WFC3).
"This image of the impact on Jupiter is fantastic" said U.S. Senator Barbara A. Mikulski, D-Md., chairwoman of the Commerce, Justice and Science Appropriations Subcommittee. "It tells us that our astronauts and ground crew at the Goddard Space Flight Center successfully repaired the Hubble telescope".
"This is just one example of what Hubble's new, state-of-the-art camera can do, thanks to the STS-125 astronauts and the entire Hubble team," said Ed Weiler, associate administrator of NASA's Science Mission Directorate. "However, the best is yet to come!".
"Hubble's truly exquisite imaging capability has revealed an astonishing wealth of detail in the 2009 impact site" said Hammel. "By combining these images with our ground-based data at other wavelengths, our Hubble data will allow a comprehensive understanding of exactly what is happening to the impact debris. My sincerest congratulations and thanks to the team who created Wide Field Camera 3 and to the astronauts who installed it!".
Co-investigator Imke de Pater of the University of California at Berkeley said: "The combination of the Hubble data with mid-infrared images from the Gemini telescope will give us an insight into changes of the vertical structure of the atmosphere due to the impact".MareKromium
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Jupiter-Impact-2010-004.jpgImpact on Jupiter! (from Hubble Space Telescope - edm)58 visiteDiscovered by Australian amateur astronomer Anthony Wesley on Sunday, July 19, 2009, the spot was created when a small object plunged into Jupiter's atmosphere and disintegrated. The only other time in history such a feature has been seen on Jupiter was 15 years ago.
"This is strikingly similar to the comet Shoemaker Levy 9 that impacted Jupiter in July 1994" said team member Keith Noll of the Space Telescope Science Institute in Baltimore, Md.
"Since we believe this magnitude of impact is rare, we are very fortunate to see it with Hubble" added Amy Simon-Miller of NASA's Goddard Space Flight Center in Greenbelt, Md. She explained that the details seen in the Hubble view shows a lumpiness to the debris plume caused by turbulence in Jupiter's atmosphere. The spot is presently twice the length of the United States.
Simon-Miller estimated that the diameter of the object that slammed into Jupiter was at least the size of several football fields. The force of the explosion on Jupiter was thousands of times more powerful than the suspected comet or asteroid that exploded over the Tunguska River Valley in Siberia in June 1908.
The WFC3, installed by the STS-125 astronauts in May, is not yet fully calibrated. So while it is possible to obtain celestial images, the camera's full power cannot yet be realized for most observations. The WFC3 can still return meaningful science images that will complement the Jupiter pictures being taken with ground-based telescopes.
This is a Natural Color image of Jupiter as seen in Visible Light.
Credit: NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team
The members of the Jupiter Impact Team are:
Dr. Heidi B. Hammel (Space Science Institute, Boulder, Colo.)
Dr. Amy Simon-Miller (NASA's Goddard Space Flight Center, Greenbelt, Md.)
Dr. Keith S. Noll (Space Telescope Science Institute, Baltimore, Md.)
Dr. Michael H. Wong (Space Telescope Science Institute, Baltimore, Md.)
Prof. John T. Clarke (Boston University, Boston, Mass.)
Prof. Imke de Pater (University of California, Berkeley, Calif.)
Dr. Glenn S. Orton (Jet Propulsion Laboratory, Pasadena, Calif.)
Dr. Agustin Sanchez-Lavega (University of the Basque Country, Spain)
CONTACT
Dwayne Brown
HQ, Washington
202-358-1726
dwayne.c.brown@nasa.gov
Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.eduMareKromium
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