| Ultimi arrivi - Jupiter: the "King" and His Moons |
Jupiter_s System-PIA01481.jpgJupiter's (Main) System65 visiteCaption NASA originale:"Jupiter and its four planet-size moons, called the Galilean Satellites, were photographed in early March by Voyager 1 and assembled into this collage. They are not to scale but are in their relative positions. (...) Nine other much smaller satellites circle Jupiter, one inside Io's orbit and the other millions of miles from the Planet.
Not visible is Jupiter's faint ring of particles, seen for the first time by Voyager 1".Apr 24, 2006
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Europa-PIA01970.jpgApproaching Europa54 visiteCaption NASA originale:"View of Europa taken from a range of 2.869.252 Km (such as about 1,6 MMs). The color composite is made from three black and white images taken through the orange, green and violet filters. The 170° Longitude is at the center of the picture; this is the face away from Jupiter. Irregular dark and bright patches on the surface are different from the patterns on the other satellites of Jupiter and those on the Moon, Mars and Mercury. Dark intersecting lines may be faults that break the crust".Apr 24, 2006
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The Galileans~0.jpgThe "Galileans"56 visiteIo, the large volcanic satellite of Jupiter, was first shown to the World in images transmitted from the Voyager 1 Spacecraft.
Unfortunately their cameras had no red filters and color pictures often had to be extrapolated substituting orange for red and violet for blue.
In the case of Io, this led to a garish 'pizza' appearance with many reproductions of the released images further wandering toward the red until Io looked like tomato soup!
Io is very bright, and largely a pale yellow with gray green to orange regions. Galileo has greatly refined the color information from Io. The albedo of Io (il primo a Sx) is a bright 0,6, while Europa (the brightest) is 0,64. Ganymede's albedo is just 0,42 and then - last - the dark Callisto is only 0,2.Apr 09, 2006
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Jupiter~0.jpgThe "true" colors of Jupiter (an interpretation)136 visiteJupiter has several narrow belts of distinct colors as well as reddish oval shaped stable cyclonic weather zones such as the 'Great Red Spot'. The overall albedo of the planet is 0,52. The colors shown in the strips are of the wider alternating belts and zones extending from either side of the often white Equatorial Zone.
This is a Voyager 1 image assembled from raw data and color balanced to approximate the colors and contrast of the Planet.Apr 09, 2006
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Jupiter_s NorthPole-PIA07783.jpgThe North Pole of Jupiter74 visiteThe South Polar Regions shown here are less clearly visible because Cassini viewed them at an angle and through thicker atmospheric haze.
The round maps are polar stereographic projections that show the North or South Pole in the center of the map and the Equator at the edge.Mar 28, 2006
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Jupiter_s SouthPole-PIA07784.jpgThe South Pole of Jupiter56 visiteThe South Polar Regions shown here are less clearly visible because Cassini viewed them at an angle and through thicker atmospheric haze.
The round maps are polar stereographic projections that show the North or South Pole in the center of the map and the Equator at the edge.
Mar 28, 2006
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Jupiter_sMap00-PIA07782-2.jpgSuper-detailed Jupiter's Map (2)60 visiteThe map shows a variety of colorful cloud features, including parallel reddish-brown and white bands, the Great Red Spot - frame 1), multi-lobed chaotic regions, white ovals and many small vortices. Many clouds appear in streaks and waves due to continual stretching and folding by Jupiter's winds and turbulence. The bluish-gray features along the north edge of the central bright band are equatorial "hot spots" meteorological systems such as the one entered by NASA's Galileo probe. Small bright spots within the orange band north of the Equator are lightning-bearing thunderstorms. The Polar Regions are less clearly visible because Cassini viewed them at an angle and through thicker atmospheric haze.
Pixels in the rectangular map cover equal increments of planetocentric latitude (which is measured relative to the center of the Planet) and longitude, extending to 180° of latitude and 360° of longitude. Mar 28, 2006
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Jupiter_sMap00-PIA07782-1.jpgSuper-detailed Jupiter's Map (1)59 visiteThis map is part of a group release of cylindrical and polar stereographic projections of Jupiter.
This color map of Jupiter were constructed from images taken by the narrow-angle camera onboard NASA's Cassini spacecraft on Dec. 11 and 12, 2000, as the spacecraft neared Jupiter during its flyby of the giant planet. Cassini was on its way to Saturn. They are the most detailed global color maps of Jupiter ever produced. The smallest visible features are about 120 Km (approx. 75 miles) across.
The maps are composed of 36 images: a pair of images covering Jupiter's Northern and Southern Hemispheres was acquired in two colors every hour for nine hours as Jupiter rotated beneath the spacecraft. Although the raw images are in just two colors, 750 nanometers (near-infrared) and 451 nanometers (blue), the map's colors are close to those the human eye would see when gazing at Jupiter.Mar 28, 2006
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Jupiter_s New Spot.jpgThe "New Red Spot" of Jupiter64 visiteJupiter's "Great Red Spot" is a swirling storm seen for over 300 years, since the begining of telescopic observations of the Solar System's ruling gas giant. But over the last month, the Great Red Spot has been joined by a new one (informally named "Red Spot Jr."). Thought to be similar to the Great Red Spot itself, this smaller Red Spot was actually seen to form as smaller whitish oval-shaped storms merged and then developed the remarkable reddish hue. This webcam image showing the two red tinted Jovian storms was recorded on the morning of March 12, 2006, from the Central Coast of New South Wales, Australia - part of a series showing Jupiter's rotation. Similar in diameter to planet Earth, Red Spot Jr. is expected to last for a while and trails the Great Red Spot by about an hour as the Planet rotates. Astronomers still don't exactly understand why Jupiter's red spots...are red.Mar 18, 2006
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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". Gen 03, 2006
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Jupiter-PIA02401.jpgLook at Me!62 visiteWhen 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.Gen 03, 2006
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Jupiter-PIA02865-4.jpgA "deep look" in the "deep clouds" of Jupiter57 visiteFinally, this is the combination of the 3 images taken from Cassini using the 3 different filters.
This picture reveals cloud structures and movements at different depths in the atmosphere around Jupiter's South Pole. Cassini's cameras come equipped with filters that sample 3 wavelengths where Methane gas absorbs light. These are in the RED (619 nnmts) and in the NEAR-INFRARED (at 727 and 890 nnmts). Absorption in the 619 nnmts filter is weak. It is stronger in the 727 nnmts band and very strong in the 890 nnmts band where 90% of the light is absorbed by Methane gas.
Light in the weakest band can penetrate the deepest into Jupiter's atmosphere. It is sensitive to the amount of cloud and haze down to the pressure of the water cloud (which lies at a depth where pressure is about 6 times the atmospheric pressure at sea level on the Earth).
Light in the strongest methane band is absorbed at high altitude and is sensitive only to Ammonia cloud level and higher (with pressures less than about one-half of Earth's atmospheric pressure) and the middle methane band is sensitive to the ammonia and ammonium hydrosulfide cloud layers as deep as two times Earth's atmospheric pressure.Gen 03, 2006
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