Saturn: the "Ringed Beauty" and His Moons
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Enceladus-Fly-By-EB.jpgEnceladus' Fly-By (Image-Mosaic; credits: Elisabetta Bonora - Lunexit Team)57 visiteUn altro Lavoro che Vi presentiamo con immenso piacere e soddisfazione...MareKromium
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Enceladus-FullColor-MF-PCF1.jpgEnceladus (an Image-Mosaic in Natural Colors; credits for the additional process. and color.: Drr Marco Faccin and Paolo C. Fienga - Lunexit Team)85 visitenessun commentoMareKromium
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Enceladus-FullColor-MF-PCF2.jpgEnceladus (an Image-Mosaic in Natural Colors; credits for the additional process. and color.: Drr Marco Faccin and Paolo C. Fienga - Lunexit Team)93 visitenessun commentoMareKromium
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Enceladus-FullColor-MF1.jpgEnceladus (an Image-Mosaic in RAW Natural Colors; credits for the additional process. and color.: Dr Marco Faccin - Lunexit Team)84 visitenessun commentoMareKromium
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Enceladus-GroundTrack-PIA07723_modest.jpgEnceladus: the "Ground-Track"53 visiteThis graphic shows Cassini's path, or Ground Track, as it crossed over the surface of Enceladus near the time of closest approach during the flyby on July 14, 2005. The Ground Track is indicated by a yellow line, marked by increments of 10" before and after closest approach. The spacecraft came within 175 Km from the surface of Enceladus at closest approach.
The red contour encloses the Region on Enceladus around the South Pole that is the approx. boundary of the warm region, as measured by the Composite Infrared Spectrometer (CIS) on Cassini. As previously announced, temperatures observed within this region reached as high as 110 Kelvin (about -260 Fahrenheit). (...) Results like these, pouring in from various Cassini instruments, indicate the warm South Polar Region and, in particular, the 'tiger stripe' fractures straddling the South Pole, as the sources of heat, water vapor and small, icy particles.
Enceladus is a surprisingly active moon. Why its South Pole is the site of this activity is a mystery.
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Enceladus-IMG002995-br500.jpgArabian Nights...On Enceladus!53 visiteCaption NASA:"This 3-image mosaic is the highest resolution view yet obtained of Enceladus' North Polar Region. The view looks southward over cratered plains from high above the North Pole of Enceladus.
Cassini's March 2008 flyby of Enceladus was designed to directly investigate the ongoing plume activity at the moon’s South Pole, but the path of the spacecraft allowed investigation of older evidence for internal activity near the North Pole.
Compared to much of the moon's Southern Hemisphere - the South Polar Region in particular - the North Polar Region is much older and covered with craters. These craters are captured at different stages of disruption and alteration by tectonic activity and probably past heating from below. Many of the craters seen here are sliced by small parallel cracks that seem to be ubiquitous throughout the old cratered terrains on Enceladus. The mosaic also shows a variety of impact crater shapes, some with bowed-up floors and smaller craters within, very likely indicating that the icy crust in this area was at some time warmer than at present. While this conclusion was previously reached from NASA Voyager spacecraft images, these new data provide a much more detailed look at the fractures that modify the surface. This data will give a significantly improved comparison of the geologic history at the satellite's north pole with that at the South Pole.
Two prominent craters in this view, Ali Baba and Aladdin (the two overlapping craters near center), are among the largest craters known on Enceladus.
Several areas of much younger terrain are visible in this mosaic, including Samarkand Sulci, an area of disrupted terrain that runs North-South at left of center, and the "Leading Hemisphere Terrain", a region, seen at right, filled with tectonic fractures, ridges and "ridged terrain".
Samarkand Sulci slices through some prominent craters that were seen in Voyager images. At that time, it was thought that the portions of the craters that extend into Samarkand were completely destroyed by whatever process formed Samarkand. However, Cassini images show remnants of the crater rims that have survived. This new insight provides a benchmark for measuring how tectonic processes modify older terrains, and will also help imaging scientists develop a more accurate timeline for the geologic history of these terrains.
Lit terrain seen here is on the Saturn-Facing Hemisphere of Enceladus.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 12, 2008. The view was acquired at a distance of approx. 32.000 Km (about 20.000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 115°.
Image scale is roughly 176 meters (577 feet) per pixel".MareKromium
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Enceladus-MF-PCF-LXTT.jpgTiger Stripes (Absolute Natural Colors; credits for the additional process. and color.: Drr Marco Faccin and Paolo C. Fienga - Lunexit Team)89 visitenessun commentoMareKromium
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Enceladus-MF1-LXTT.jpgThe "Blue Scars" of Enceladus (an Image-Mosaic in Absolute Natural Colors; credits for the additional process. and color.: Dr Marco Faccin - Lunexit Team)85 visitenessun commentoMareKromium
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Enceladus-MF2-LXTT.jpgThe "Head" of Enceladus (an Image-Mosaic in Absolute Natural Colors; credits for the additional process. and color.: Dr Marco Faccin - Lunexit Team)78 visitenessun commentoMareKromium
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Enceladus-Model0-PIA03553.jpgWater Vapor & Particles Over Enceladus54 visiteThis plot shows results from Cassini's Ion Neutral Mass Spectrometer (INMS) and Cosmic Dust Analyzer (CDA), obtained during the spacecraft's close approach to Enceladus on July 14, 2005. Within a minute of that closest approach, the 2 instruments detected material coming from the surface of the Moon. The INMS measured a large peak in the abundance of water vapor at approx. 35" before closest approach to Enceladus, as it flew over the South Polar Region at an altitude of 270 Km. The high rate detector of the CDA observed a peak in the number of fine, powder-sized icy particles coming from the surface approx. 1' before reaching closest approach, at an altitude of 460 Km. The character of these detections is very similar to the venting of vapor and fine, icy particles from the surfaces of comets when they are warmed as they near the Sun. On Enceladus, it is believed that internal heat, possibly from tidal forces, is responsible for the activity. The close but different occurrences of the two detections are yielding important clues to the location of the vents and even the venting process.
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Enceladus-Model1-PIA07725.jpg"Warm" Ice on Enceladus (Model 1)53 visiteOriginal NASA caption:"This graphic represents a possible model for mechanisms that could generate the water vapor and tiny ice particles detected by Cassini over the Southern Polar terrain on Enceladus. This Model shows sublimation of warmed surface ice. Sublimation is to cause to change directly from a solid to a gas, or from a gas to a solid, without becoming a liquid".
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Enceladus-Model2-PIA07726-br500.jpg"Warm" Ice on Enceladus (Model 2)53 visiteOriginal NASA caption:"This graphic represents a second possible model for mechanisms that could generate the water vapor and tiny ice particles detected by Cassini over the Southern Polar terrain on Enceladus. This model shows venting by plumes".
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