| Risultati della ricerca nelle immagini - "Spokes" |
PSP_001910_2215_RED_abrowse-00.jpgUnnamed Crater in Utopia Planitia (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)54 visiteThis observation shows an Unnamed Impact Crater located in Utopia Planitia; this Crater is more than 10 Km (6,25 miles) in diameter and approx. 700 meters (765 yards) deep. Different features in and around this Crater may indicate the presence of fluid beneath the Surface.
Linear features radiating outward from the Crater's Rim are evident. Closer examination shows these features are formed by rocks and finer soils that are located along a straight line; technically, they are "Spokes" produced immediately after the impact by very fast outward-moving materials ejected from the contact-zone. Because these Ejecta came from deep under the Crater, their composition will tell us what type of rocks are under the Surface.
A MOC context image of this Crater shows its Ejecta Materials form an elevated "Pedestal," shaped like a pancake. The Pedestal is approx. 20 Km (about 12,5 miles) in diameter. "Pedestal craters" such as this may have formed because ice beneath the Surface melted when the impact occurred.MareKromium
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Saturn-PIA07731-1.jpgSpokes (1)57 visiteAfter much anticipation, Cassini has finally spotted the elusive "spokes" in Saturn's Rings.
"Spokes" are the ghostly Radial Markings discovered in the Rings by NASA's Voyager spacecraft 25 years ago. Since that time, Spokes had been seen in images taken by NASA's Hubble Space Telescope but had not, until now, been seen by Cassini.
These three images, taken over a span of 27', show a few faint, narrow Spokes in the outer B-Ring. The Spokes are about 3500 Km (2200 miles) long and about 100 Km wide (60 miles). The motion of the Spokes here is from left to right.
They are seen just prior to disappearing into the Planet's shadow on the Rings.
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Saturn-PIA07731-2.jpgSpokes (2)54 visiteAt the bottom left corner of the 1 st and 2nd image, the bright inner edge of the A-Ring is visible. Continuing radially inward (or toward Saturn) are several bands that lie within the Cassini Division, bounded by the bright outer edge of the B-Ring. The rounded shadow of Saturn cuts across the Rings in the image at right.
Cassini's first sighting of Spokes occurs on the unilluminated side of the Rings, in the same region in which they were seen during the Voyager flybys. Although the most familiar Voyager images of spokes showed them on the sunlit side of the Rings, spokes also were seen on the unilluminated side.
In Voyager images, when Spokes were seen at low phase angles, they appeared dark; when seen at high phase angles, they appeared bright. The Spokes seen here are viewed by Cassini at a very high phase angle, which is about 145° at the center of each image.
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Saturn-PIA07731-3.jpgSpokes (3)54 visiteImaging team members will be studying the new Spoke images and will maintain their vigil for additional Spoke sightings.
These images were taken using the clear filters on Cassini's Wide-Angle Camera on Sept. 5, 2005, at a mean distance of 318.000 Km (198.000 miles) from Saturn. The radial scale on the Rings (the image scale at the center of each image) is about 17 Km (about 11 miles) per pixel.
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The_Rings-PIA10423.jpgSpooky Spokes! (MULTISPECTRUM; credits: Lunexit)57 visiteCaption NASA:"As they wheel about the Planet, Saturn's sunlit Rings often exhibit dark, radial markings called "spokes". Spokes are seen only in the broad B-Ring, and can also appear bright in certain viewing geometries.
This view looks toward the sunlit side of the Rings from about 11° below the Ring-Plane.
Pandora (about 81 kilometers, or approx. 50 miles across) is a speck above the Rings at left. The Planet's shadow darkens the Ring-Plane at lower right.
The image was taken in visible light with the Cassini Spacecraft wide-angle camera on June 3, 2008. The view was acquired at a distance of approx. 1 MKM (about 636.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 19°.
Image scale is roughly 61 Km (approx. 38 miles) per pixel".MareKromium
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