These two images, taken about eight minutes apart, show clump-like structures and a great deal of dust in Saturn's ever-changing F ring. The images show an object-interior to and detached from the bright core of the F ring that appears to be breaking up into discrete clumps.
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Cassini scientists have been monitoring clumps in the F ring for more than two years now, trying to understand whether these represent small permanent moonlets or transient aggregates of material. This view looks toward the unlit side of the rings from about 35 degrees above the ringplane. The images were taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 23, 2006 at a distance of approximately 2 million kilometres from Saturn. Image scale is 12 kilometres per pixel.
The striated appearance of the F ring is immediately apparent in the region of the ring that trails behind the moon Prometheus. The F ring is characterised here by dark gores that stretch inward toward the planet and forward in the direction of motion.
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This image has been expanded in the horizontal direction by a factor of five in order to make radial variations more prominent. The curvature of the rings is also exaggerated by the horizontal stretch. The exterior flanking ringlets (above the bright ring core) are not disturbed by Prometheus to the great degree seen in the inner ringlets. This view looks toward the unlit side of the rings from about 31 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 25, 2006 at a distance of approximately 1.7 million kilometres from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 162 degrees. Scale in the original image is 10 kilometres per pixel.
Saturn's sunlit rings gleam in the blackness as two icy moons cruise past in the foreground. Enceladus (505 kilometres across) is a small crescent near upper left; Janus (181 kilometres across) is a speck above the F ring, near centre. Janus was brightened slightly for visibility. This view looks toward the lit side of the rings from about 5 degrees below the ringplane.
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This image was taken in visible red light with the Cassini spacecraft wide-angle camera on Nov. 7, 2006, at a distance of approximately 1.1 million kilometres from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 139 degrees. Image scale on the sky at the distance of Saturn is 63 kilometres per pixel.
This close-up of the inner edge of the Cassini Division shows an enormous amount of structure, including a grainy texture in the bright outer B ring material near the gap edge.
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An extreme enhancement of the original image, presented at right, reveals the grainy region with greater clarity. This view looks toward the lit side of the rings from about 54 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 8, 2006 at a distance of approximately 378,000 kilometres from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 68 degrees. Image scale is 2 kilometres per pixel.
This "difference image" is actually a composite of two images of the B ring, taken about 45 seconds apart. The view illustrates how the several spokes imaged here moved between exposures. The spokes were bright against the rings in both original images, but the brightness of the earlier image was reversed so that the spoke movement is easy to discern. The "dark" image of the spokes was taken first, thus rotation in the scene is toward the bottom.
The topmost spoke is about 2,500 kilometres long and about 600 kilometres wide. The separation between the top spoke and the bottom one is about 8,500 kilometres. The available evidence seems to indicate that spokes are radial when generated and then shear out as they orbit the planet, eventually dispersing and fading out after about three and one-half hours. All of these spokes are nearly radial on their trailing (top) edges, except for the thin, bottommost spoke. That spoke and the wedge-shaped one above it have a shear of about 38 degrees, meaning they have an age of about two and one-quarter hours, assuming they were first radial and then sheared their entire lives. The faint horizontal banding in the image is due to "noise" in the spacecraft electronics that was picked up by the camera system and enhanced by the processing technique used here. This view looks toward the unlit side of the rings from about 32 degrees above the ringplane.
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The two images were taken with the Cassini spacecraft narrow-angle camera on Nov. 1, 2006 at a distance of approximately 1.7 million kilometres from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 162 degrees. Image scale on the sky at the distance of Saturn is 10 kilometres per pixel.