| Piú viste - SOLAR SYSTEM |
Dione-N00041243.jpgDione's Fly-By (16): from about 1.835 Km61 visitenessun commento
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Mimas-N00041424.jpgMimas and the Rings61 visiteN00041424.jpg was taken on October 13, 2005 and received on Earth October 14, 2005. The camera was pointing toward MIMAS - distant approximately 710.721 Km away - and the image was taken using the CL1 and GRN filters. This image has not been validated or calibrated.
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Mimas-W00011156.jpgMimas in the night61 visiteOriginal caption:"W00011156.jpg was taken on October 13, 2005 and received on Earth October 14, 2005. The camera was pointing toward MIMAS - at approximately 710.418 Km away - and the image was taken using the CB2 and IRP90 filters. This image has not been validated or calibrated".
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Jupiter_s Rings-PIA01628.jpgThe Rings of Jupiter (2)61 visiteScientists studying data from Galileo spacecraft have found that the Ring System is made up of impact debris created when meteoroids, which are fragments of comets and asteroids, slam into Jupiter`s four smallest satellites. The top panel shows that the Main Ring (red) is formed mostly from meteoroid impact debris kicked up from the innermost moons, Metis (m) and Adrastea (a). Since both satellites orbit in paths not inclined to Jupiter's equator, the Main Ring appears as a narrow line. The middle panel shows the additional effect of dust ejected from the satellite Amalthea (A), responsible for producing 1 of the 2 moon components of the Gossamer Ring. Amalthea's orbit is inclined to Jupiter's equatorial plane and at different times the satellite's vertical position can range anywhere between the 2 extreme limits shown. Dust ejected from Amalthea (orange) produces a ring whose thickness equals Amalthea's vertical projections beyond Jupiter's equatorial plane. The lower panel shows the additional effect of dust ejected from Thebe (T), which makes up the second component (shown in green) of the gossamer ring. Again, the two positions shown represent the maximum projections of Thebe from Jupiter's equatorial plane. This component of the gossamer ring is thicker than the component due to Amaltheas dust because Thebe's orbit is more inclined than that of Amalthea.
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Jupiter_s Rings-PIA01627.jpgThe Rings of Jupiter (1)61 visiteOriginal caption:"This schematic cut-away view of the components of Jupiter's Ring System shows the geometry of the Rings in relation to Jupiter and to the small inner moons, which are the source of the dust forming the Rings themselves. The innermost and thickest Ring, shown in gray shading, is the halo that ends at the Main Ring. The thin, narrow Main Ring, shown with red shading, is bounded by the 16- Km-wide (10-miles) satellite Adrastea and shows a marked decrease in brightness near the orbit of Jupiter's innermost moon, Metis. It is composed of fine particles knocked off Adrastea and Metis. Although the orbits of Adrastea and Metis are about 1000 Km (about 600 miles) apart, that separation is not depicted in this drawing. Impacts by small meteoroids (fragments of asteroids and comets) into these small, low-gravity satellites feed material into the Rings. Thebe and Amalthea, the next 2 moons in increasing distance from Jupiter, supply dust which forms the thicker, disk-like 'Gossamer' Rings".
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Prometheus-N00041980.jpg"Family Group": Prometheus, Dione and Titan61 visiteOriginal caption:"N00041980.jpg was taken on October 17, 2005 and received on Earth October 18, 2005. The camera was pointing toward PROMETHEUS - approximately 2.358.256 Km away - and the image was taken using the CL1 and CL2 filters. This image has not been validated or calibrated".
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Europa-PIA00723.jpgBeautiful Europa...61 visiteThis global view of Europa shows the location of a four-frame mosaic of images taken by NASA's Galileo spacecraft, set into low-resolution data obtained by the Voyager spacecraft in 1979. Putting new data into its surrounding context is a technique that allows scientists to better understand features observed on planetary surfaces. The Galileo spacecraft obtained these images during its first orbit of Jupiter at a distance of about 156.000 km (such approx. 96.300 miles) on June 27, 1996. The finest details that can discerned in this picture are about 1,6 Km (1 mile) across. North is to the top.
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Europa-mosaic-PIA01407.jpgDifferent surface features of Europa61 visite1. Triple bands and dark spots were the focus of some images from Galileo's eleventh orbit of Jupiter. Triple bands are multiple ridges with dark deposits along the outer margins. Some extend for thousands of kilometers across Europa's icy surface. They are cracks in the ice sheet and indicate the great stresses imposed on Europa by tides raised by Jupiter, as well as Europa's neighboring moons, Ganymede and Io. The dark spots or "lenticulae" are spots of localized disruption.
2. The Conamara Chaos region reveals icy plates which have broken up, moved, and rafted into new positions. This terrain suggests that liquid water or ductile ice was present near the surface. On Galileo's twelfth orbit of Jupiter, sections of this region with resolutions as high as 10 meters per picture element will be obtained.
3. Mannann'an Crater is a feature newly discovered by Galileo in June 1996. Color and high resolution images (to 40 meters per picture element) from Galileo's fourteenth orbit of Jupiter will offer a close look at the crater and help characterize how impacts affect the icy surface of this moon.
4. Cilix, a large mound about 1.5 kilometers high, is the center of Europa's coordinate system. Its concave top and what may be flow like features to the southwest of the mound are especially intriguing. The origin of this feature is unknown at present. Color, stereo, and high resolution images (to 65 meters per picture element) from Galileo's fifteenth orbit of Jupiter will offer new insights and resolve questions about its origin.
5. Images of Agenor Linea (white arrow) and Thrace Macula (black arrow) with resolutions as high as 30 meters per picture element will be obtained during Galileo's sixteenth orbit of Jupiter. Agenor is an unusually bright lineament on Europa. Is the brightness due to new ice, and if so, does it represent recent activity? Could the dark region of Thrace Macula be a flow from ice volcanism?
6. Images of Europa's south polar terrain obtained during Galileo's seventeenth orbit of Jupiter will offer insights into the processes which are active in this region. Is the ice crust thicker near Europa's poles than near the equator? The prominent dark line running from upper left to lower right through the center of this image is Astypalaea Linea. It is a fault about the length of the San Andreas fault in California and is the largest such fault known on Europa. Images with resolutions of 48 meters per picture element will be obtained to examine its geologic structure.
7. This long lineament, Rhadamanthys Linea. is spotted with dark "freckles". Are these freckle features formed by icy volcanism? Is this an early form of a triple band? Stereo and high resolution (to 46 meters per picture element) obtained during Galileo's eighteenth orbit of Jupiter may indicate whether the lineament is the result of volcanic processes or is formed by other surface processes.
8. During Galileo's nineteenth orbit of Jupiter, images of Europa will be taken with very low sun illuminations, similar to taking a picture at sunset or sunrise. The object will be to search for backlit plumes issuing from icy volcanic vents. Such plumes would be direct evidence of a liquid ocean beneath the ice. Resolutions will be as high as 40 meters per picture element. This picture was simulated image from Galileo data obtained during the spacecraft's second orbit of Jupiter in September 1996.
North is to the top of the pictures. During orbit 13, the Galileo spacecraft was behind the sun from our vantage point on Earth so it did not obtain or transmit data from that orbit. The left two images in the bottom row were obtained by NASA's Voyager 2 spacecraft in 1979; the remaining images were obtained by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft in 1996.
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Europa-PIA01144.jpgCold, cold world...61 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.
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Janus-PIA07615.jpgJanus and Epimetheus61 visiteOriginal caption:"Outside the soft edge of Cassini's F-Ring, Epimetheus and Janus negotiate their nearly-shared orbit. The two moons' orbits are typically about 50 Km (approx. 30 miles) apart, and the moons actually change orbits every few years: one moon becoming the innermost of the pair, the other becoming the outermost.
Epimetheus' diameter is 116 Km while Janus' diameter is 181 Km across.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 8, 2005, at a distance of approx. 1,5 MKM (about 1 MMs) from Saturn. The image scale is about 11 Km (roughly 7 miles) per pixel on the two moons".
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The Rings-PIA07750.jpgSurfing the waves of the F-Ring (from 1,1 MKM)61 visiteOriginal caption:"This mosaic of 15 Cassini images of Saturn's F-Ring shows how the moon Prometheus creates a gore in the Ring once every 14 h and 42', as it approaches and recedes from the F-Ring on its eccentric orbit. The individual images have been processed to make the Ring appear as if it has been straightened, making it easier to see the Ring's structure. The mosaic shows a Region 147.000 Km (about 91.000 miles) along the Ring (horizontal direction in the image); this represents about 60° of Longitude around the Ring. The Region seen here is about 1500 Km (900 miles) across (vertical direction). The first and last images in the mosaic were taken approximately 2,5 hours apart.
Each dark channel, or "gore," is clearly visible across more than 1,000 kilometers (600 miles) of the ring and is due to the gravitational effect of Prometheus (102 kilometers, or 63 miles across), even though the moon does not enter the F ring. The channels have different tilts because the ring particles closer to Prometheus (overexposed, stretched, and just visible at the bottom right of the image) move slower with respect to the moon than those farther away. This causes the channels to shear with time, their slopes becoming greater, and gives the overall visual impression of drapes of ring material. The channels at the right are the youngest and have near-vertical slopes, while those at the left are the oldest and have near-horizontal slopes. This phenomenon has not previously been detected in any other planetary ring system, but computer simulations of the system prove that the disturbance is caused by a simple gravitational interaction. The eccentric orbit of Prometheus is gradually moving so that the moon will eventually come even closer in its closest approach to the eccentric F ring. Scientists calculate that its perturbations of the F ring will reach a maximum in December 2009".
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Pandora-N00042203.jpgPandora and...?61 visiteOriginal caption:"N00042203.jpg was taken on October 29, 2005 and received on Earth October 30, 2005. The camera was pointing toward PANDORA at approximately 459.147 Km away, and the image was taken using the CL1 and UV3 filters. This image has not been validated or calibrated".
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