This is an artist concept of the ring of debris that may orbit Saturn's second-largest moon, Rhea. The suggested disk of solid material is exaggerated in density for clarity.
Due to a decrease in the number of electrons detected by NASA's Cassini spacecraft on either side of the moon, scientists suggest that rings are the likeliest cause of these electrons being blocked before they reach Cassini.
The image of Rhea was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 17, 2007, and shows the middle northern latitudes. The large Tirawa basin is seen on the terminator at right.
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The image was taken at a distance of approximately 539,000 kilometres from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 79 degrees. Image scale is 3 kilometres per pixel.
This image of Rhea before it glided in front of Saturn's northern hemisphere, was taken in visible red light with the Cassini spacecraft narrow-angle camera on Sept. 9, 2007. This view looks toward the anti-Saturn side of Rhea.
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The image was acquired at a distance of approximately 2.8 million kilometres from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 33 degrees. Image scale is 17 kilometres per pixel. North is up.
This view of a crater on Rhea was created from images taken during Cassini's close encounter with the moon on Aug. 30, 2007. The crater is 48 kilometres wide, and its rays extend several hundred kilometres outward.
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This stereo image is a mosaic consisting of seven Cassini spacecraft narrow-angle camera images. The view is an orthographic projection centred on 12 degrees south latitude, 112 degrees west longitude and has a resolution of 45 meters per pixel. An orthographic view is most like the view seen by a distant observer looking through a telescope. North is up. The clear filter images for this stereo image were taken from distances ranging from about 17,000 kilometres (10,600 miles, for the red-coloured image) to 7,500 kilometres, for the blue/green-coloured image) from Rhea.
This image shows Rhea, Prometheus and Saturn. Rhea is in the foreground, while Prometheus is just visible near the rings about 400,000 kilometres further on. Saturn's cloud tops are about 80,000 kilometres farther still. This view looks toward the unilluminated side of the rings from less than a degree above the ringplane.
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The image was taken with the Cassini spacecraft narrow-angle camera on Aug. 13, 2007 using a spectral filter sensitive to wavelengths of infrared light centred at 750 nanometers. The view was acquired at a distance of approximately 4.1 million kilometres from Saturn. Image scale is 24 kilometres per pixel on Saturn and 21 kilometres per pixel on Rhea.
Bright, wispy markings cover the trailing hemisphere of Rhea. The features are thought to be similar in nature to the bright, icy canyons seen on Dione. North on Rhea is up and rotated 17 degrees to the left.
The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 22, 2007. The view was acquired at a distance of approximately 1.2 million kilometres from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 42 degrees. Image scale is 7 kilometres per pixel.
This image of Rhea was taken in visible light by the Cassini spacecrafts narrow-angle camera on July 21, 2007, when it was approximately 783,000 kilometres away, and at a Sun-Rhea-spacecraft angle of 76 degrees.
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North is up and rotated 12 degrees to the left. The image scale is 5 kilometres per pixel.