| Piú votate - Jupiter: the "King" and His Moons |
Jupiter-NO-00-022807_3.jpgJupiter! (after New Horizons' Fly-By)56 visitenessun commentoMareKromium
(4 voti)
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Callisto-HR-00.jpgCallisto: the full disk (HR)54 visitenessun commento
(4 voti)
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Jupiter-Storms.jpgColliding "Spots"57 visiteCaption NASA originale:"Two storms systems larger than Earth are nearly colliding right now on planet Jupiter. No one was sure what would happen, but so far both storms have survived. In the above false-color infrared image taken last week by the Gemini Observatory in Hawaii, the red spots appear white because their cloud tops tower above other clouds. Blue color represents lower clouds than white, while clouds colored red are the deepest. The smaller red spot, sometimes called Red Spot Jr. or just Oval BA, turned red earlier this year for reasons unknown. If both Jovian hurricanes continue to survive, they will surely pass near each other again in a few years since they revolve around Jupiter at different rates. Astronomers will continue to monitor Red Spot Jr. closely, however, to see if it will remain red when it rotates away from the larger Great Red Spot".
(4 voti)
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Jupiter_s NorthPole-PIA07783.jpgThe North Pole of Jupiter73 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.
(4 voti)
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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.
(4 voti)
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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.
(4 voti)
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Jupiter-PIA02865-3.JPGJupiter's clouds - 890 nnmts filter59 visiteTo the North-West (above and to the left) of the dark feature is a small cloud that is bright in the 619-nnmts image but has no contrast at the other wavelengths. This is the signature expected for a thick water cloud. Another feature seen only in the weak-methane ratio is a dark ring near the center of the image.
This feature is probably a counter-clockwise rotating, upwelling core surrounded by a sinking perimeter with diminished cloudiness. The fact that it is seen only in the weak methane ratio indicates the effects of a lower-level circulation that does not penetrated to the upper ammonia cloud level and may be confined to the deeper water cloud.
The opposite behavior is evident in an oval storm that appears dark in 727 and 890 nnmts images, but is absent in the weak 619-nnmts frame. It is located to the South-West of the Great Red Spot. Further to the West - at slightly more Northerly Latitudes - are a series of small spots that are dark at all wavelengths.
These and a myriad of other contrast features at many latitudes reveal much about Jupiter's complicated cloud structure and meteorology.
(4 voti)
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Europa-PIA01144.jpgCold, cold world...54 visiteThis infrared image of Europa, showing heat radiation from its surface at a wavelength of 27 microns (millionths of a meter), provides the best view yet of Europa's daytime temperatures. Temperatures, derived from the brightness of the infrared radiation, can be determined from the colors by reference to the scale at the bottom of the image. The image, taken by Galileo spacecraft, shows the full disk of Europa, highly distorted by the relative motion of Europa and the spacecraft, centered on longitude 190°, with North at the top. The data show that midday temperatures at Europa's Equator reach about 130° Kelvin (-225 F). The surface is even colder toward the Poles and before or after midday.
Small patches of different colors on Europa's disk show regions that are warmer or cooler than their immediate surroundings: the warm patches are generally relatively dark and thus absorb more sunlight, than neighboring Regions, while the cool patches are relatively bright. In the lower left corner, heat radiation from Jupiter itself, appearing orange-red in this representation, can be seen peeking out from behind Europa's disk.
The image was taken with Galileo's PPR (Photopolarimeter-Radiometer) instrument on the spacecraft's seventh orbit around Jupiter, from a range of about 65,000 kilometers (40,389 miles). Surface temperatures derived from the strength of infrared radiation, as was done here, are called "brightness temperatures", and may be slightly in error.
The PPR instrument builds up an image by slowly scanning across the target over a period of up to one hour. The motion of Galileo relative to Europa during this time causes distortions in the satellite shape on the image, which therefore does not appear circular. The small overlapping circles that make up the image show the size of the area, about 160 kilometers (99 miles) across, covered by each individual PPR measurement. Blue spots in the dark sky in the right-hand portion of the image are due to noise.
(4 voti)
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Europa-PIA01212.jpgEuropa's terminator104 visiteThis image of Europa was obtained by the Solid State Imaging (CCD) System on board NASA's Galileo spacecraft during its 4th orbit of Jupiter. Linear features with bright central stripes referred to as "Triple Bands" (TB) are seen to transect the surface of Europa. Several of these TBs are over 700 Km in length. In the left side of the image the surface of Europa is seen to be locally pitted and irregular. Ridges less than 100 Km in length are also visible in this Region.
The area seen in this image, centered near 27° South and 300° West, is 760 (456 miles) by 850 Km (510 miles) across, which is approximately the size of the state of Texas or the country of France. North is to the top of the image, with the sun illuminating the surface from the left. The image which has a resolution of 1,3 Km per picture element (e cioè "per pixel") was obtained on December, 19th, 1996.
(4 voti)
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Europa-PIA01101.jpgWhen the Sun sets...On Europa55 visiteThis image of Europa was taken by the Galileo spacecraft under "low-Sun" illumination - the equivalent of taking a picture from a high altitude at Sunrise or Sunset. Note that in this image the topography of the terrain is emphasized. Planetary geologists use information from images acquired under a variety of lighting conditions to identify different types of structures and interpret how they formed. For example, the length of the shadow cast by a feature (e.g. a ridge or knob) is indicative of that feature's height. In this recent image, ridges and irregularly shaped knobs ranging in size from 5 Km across down to the limit of resolution (0,44 Km/pixel) can be seen. Measurements from shadow lengths indicate that features in this image range from tens of meters up to approx. 100 mt in height. The Galileo spacecraft acquired this image of Europa's surface during its 3rd orbit around Jupiter. The image covers an area of approx. 40 by 75 Km, centered near 10° South and 190° West.
(4 voti)
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Europa-Ice_Floes-PIA00291.jpgThe typical "surface features" of Europa57 visiteJupiter's moon Europa, as seen in this image taken June 27, 1996 by NASA's Galileo spacecraft, displays features in some areas resembling ice floes seen in Earth's polar seas. Europa, about the size of Earth's moon, has an icy crust that has been severely fractured, as indicated by the dark linear, curved, and wedged-shaped bands seen here. These fractures have broken the crust into plates as large as 30 kilometers (18.5 miles) across. Areas between the plates are filled with material that was probably icy slush contaminated with rocky debris. Some individual plates were separated and rotated into new positions. Europa's density indicates that it has a shell of water ice as thick as 100 kilometers (about 60 miles), parts of which could be liquid. Currently, water ice could extend from the surface down to the rocky interior, but the features seen in this image suggest that motion of the disrupted icy plates was lubricated by soft ice or liquid water below the surface at the time of disruption. This image covers part of the equatorial zone of Europa and was taken from a distance of 156,000 kilometers (about 96,300 miles) by the solid-state imager camera on the Galileo spacecraft. North is to the right and the sun is nearly directly overhead. The area shown is about 360 by 770 kilometers (220-by-475 miles or about the size of Nebraska), and the smallest visible feature is about 1.6 kilometers (1 mile) across.
(4 voti)
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Europa-Craters-Unnamed_Crater-PIA00294.jpgFresh features on Europa54 visiteA newly discovered impact crater can be seen just right of the center of this image of Jupiter's moon Europa returned by NASA's Galileo spacecraft camera. The crater is about 30 kilometers (18.5 miles) in diameter. The impact excavated into Europa's icy crust, throwing debris (seen as whitish material) across the surrounding terrain. Also visible is a dark band, named Belus Linea, extending east-west across the image. This type of feature, which scientists call a 'triple band,' is characterized by a bright stripe down the middle. The outer margins of this and other triple bands are diffuse, suggesting that the dark material was put there as a result of possible geyser-like activity which shot gas and rocky debris from Europa's interior. The curving 'X' pattern seen in the lower left corner of the image appears to represent fracturing of the icy crust and infilling by slush which froze in place. The crater is centered at about 2 degrees north latitude by 239 degrees west longitude. The image was taken from a distance of 156,000 kilometers (about 96,300 miles) on June 27, 1996, during Galileo's first orbit around Jupiter. The area shown is 860 by 700 kilometers (530 by 430 miles), or about the size of Oregon and Washington combined.
(4 voti)
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