Saturn: the "Ringed Beauty" and His Moons
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Prometheus-PIA08916~0.jpgOrb-at-Work! (natural colors; credits: Lunexit)64 visiteCaption NASA:"Prometheus draws material from the F-Ring along an invisible thread of gravity. Near lower left is an identical feature the moon created on a previous pass near the Ring.
Prometheus (approx. 102 Km, or about 63 miles across) is overexposed in this image, which was taken as part of a sequence designed to help refine scientists' understanding of the orbits of Saturn's small moons. This view looks toward the unlit side of the Rings from about 41° above the Ring-Plane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 14, 2007 at a distance of approx. 1,8 MKM (such as about 1,1 MMs) from Prometheus.
Image scale is roughly 11 Km (about 7 miles) per pixel". MareKromium
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Prometheus-PIA08947~0.jpgCosmic "Through-and-Through"!58 visiteCaption NASA:"Prometheus pulls away from an encounter with Saturn's F-Ring, leaving behind a reminder of its passage.
Prometheus (about 102 Km, or 63 miles across) approaches closely to the F-Ring once during each circuit around Saturn, disturbing the orbits of the small particles in the Ring and creating a streamer of material that then shears out, following the moon as it speeds off.
This view looks toward the unilluminated side of the Rings from about 37° above the Ring-Plane. Prometheus is brightly lit by the Sun on one side and lit more modestly by Saturn's reflected light on the other side.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 18, 2007 at a distance of approx. 2 MKM (about 1,2 MMs) from Prometheus and at a Sun-Prometheus-spacecraft, or phase angle of 87°. Image scale is roughly 12 Km (about 7 miles) per pixel".
MareKromium
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Prometheus-PIA09834.jpgThe "visual meaning" of Gravity68 visiteCaption NASA:"Two dark gores in Saturn's F-Ring demonstrate the gravitational influence of the shepherd moon Prometheus.
The older gore at the top of this view is at a steeper angle than the newer addition just above and to the left of Prometheus, since the former has sheared out over the course of an orbit: particles on the inner (right) side of the F-Ring travel faster in the same amount of time than the particles on the outer (left) side, leaving the outer particles behind. Prometheus (102 Km, or about 63 miles across) is lit at left by direct sunlight and at right by reflected light from Saturn. The bright, sunlit portion of the moon is overexposed.
Two background stars are captured above Prometheus in this view, which looks toward the unilluminated side of the Rings from about 33° above the Ring-Plane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 1, 2008. The view was acquired at a distance of approx. 1,5 MKM (such as Rabout 956.000 miles from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 62°.
Image scale is roughly 9 Km (approx. 6 miles) per pixel".
MareKromium
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Prometheus-PIA09916.jpgSpotting Prometheus (MULTISPECTRUM; credits: Lunexit)72 visiteCaption NASA:"The flattened, potato-like form of Prometheus glides silently within the Roche Division, between Saturn's A and F-Rings.
Prometheus (86 Km, or about 53 miles across at its widest point) is on the side of the Rings closest to the Cassini Spacecraft in this view. The image looks toward the sunlit side of the Rings from about 1° below the Ring-Plane.
The image was taken in visible light with the Cassini Spacecraft narrow-angle camera on May 2, 2008. The view was acquired at a distance of approx. 1,1 MKM (such as about 660.000 miles) from Prometheus.
Image scale is roughly 6 Km (about 4 miles) per pixel".MareKromium
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Prometheus-PIA10593.jpgStreamer Channel (Natural Colors; credits: Lunar Explorer Italia)67 visiteCaption NASA:"Half an hour after Prometheus tore into this region of Saturn's F -Ring, the Cassini Spacecraft snapped this image just as the moon was creating a new Streamer in the Ring. The dark pattern shaped like an upside down check mark in the lower left of the image is Prometheus and its shadow.
The potato shaped moon can just be seen coming back out of the Ring. The moon's handiwork also is apparent in 2 previous Streamer-Channel formations on the right of the image. The darkest Streamer-Channel stretching from the top right to the center of the image shows Prometheus' previous apoapse passage about 15 hours earlier. A fainter, even earlier channel extends to the edge of the image.
Prometheus (about 86 Km, or approx. 53 miles across) dips into the inner edge of the F-Ring when it reaches apoapse, the moon's farthest orbital point from Saturn. At apoapse, the moon's gravity pulls particles of the ring outward into a streamer.
As Prometheus moves onward toward periapse — its orbit's closest point to the Planet — the Streamer gets longer. Then, as Prometheus moves back toward apoapse, the Streamer breaks apart which results in a dark channel.
This Streamer-Channel cycle repeats once every orbit with the Streamer-Channel features being streamers during Prometheus periapse and channels during Prometheus apoapse. The F-Ring is overexposed in this image which has been brightened to reveal the moon.
This view looks toward the unilluminated side of the Rings from about 18° above the Ring-Plane. The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on Jan. 14, 2009.
The view was obtained at a distance of approx. 555.000 Km (345.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 145°.
Image scale is roughly 3 Km (a little less than 2 miles) per pixel".MareKromium
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Prometheus-PIA11531.jpgPrometheus54 visiteCaption NASA:"The moon Prometheus and a bit of Saturn's Northern Hemisphere are both brilliantly lit by the Sun here, making the A-Ring seem dim in comparison.
The bright limb of Saturn's Northern Hemisphere can be seen through the A-Ring in the lower left of the image.
Prometheus (about 86 Km, or approx. 53 miles across) orbits in the Roche Division between Saturn's A and F-Ring.
For a similar view of Pandora, another of the F-Ring's Shepherding Moons, see PIA09899.
This view looks toward the sunlit side of the Rings, from about 20° below the Ring-Plane.
The image was taken in Red Light with the Cassini Spacecraft narrow-angle camera on May 25, 2009. The view was acquired at a distance of approx. 694,000 Km (about 431.000 miles) from Prometheus and at a Sun-Prometheus-Spacecraft, or Phase, Angle of 49°.
Image scale is roughly 3,6 Km (about 2,2 miles) per pixel".MareKromium
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Prometheus-PIA11553.jpgPrometheus, its Shadow and Streamer Channel55 visiteCaption NASA:"The moon Prometheus casts a shadow on the thin "F"-ing marked with Streamer-Channels created by the moon in this image taken as Saturn approaches its August 2009 Equinox.
The gravity of potato-shaped Prometheus (about 86 Km, or approx. 53 miles across) periodically creates Streamer-Channels in the "F"-Ring.
(For further examples and to learn more, see PIA10461 and PIA10593. If you want to watch a movie of this process, please refer to and see PIA08397).
The novel illumination geometry created as Saturn approaches its August 2009 Equinox allows moons orbiting in or near the plane of Saturn's Equatorial Rings to cast shadows onto the Rings. These scenes are possible only during the few months before and after Saturn's Equinox which occurs only once in about 15 Earth years.
To learn more about this special time and to see movies of moons' shadows moving across the Rings, see PIA11651 and PIA11660.
This view looks toward the unilluminated side of the Rings from about 52° above the Ring-Plane. The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on June 15, 2009.
The view was acquired at a distance of approx. 1,8 MKM (about 1,1 MMs) from Prometheus and at a Phase Angle of 85°.
Image scale is roughly 11 Km (a little less than 7 miles) per pixel".MareKromium
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Prometheus-PIA12593.jpgPrometheus (Possible Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)64 visiteCaption NASA:"Appearing like eyes on a potato, craters cover the dimly lit Surface of the moon Prometheus in this HR image from the Cassini Spacecraft's early 2010 flyby.
The Jan. 27 encounter represented the closest imaging sequence yet of that moon for Cassini.
This view looks toward the Trailing Hemisphere of Prometheus (about 86 Km, or approx. 53 miles across). North on Prometheus is up and rotated 8° to the right.
The moon is lit by Sunlight on the right and Saturnshine on the left.
The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on Jan. 27, 2010. The view was obtained at a distance of approx. 34.000 Km (about 21.000 miles) from Prometheus and at a Sun-Prometheus-Spacecraft, or Phase, Angle of 126°.
Image scale is roughly 200 meters (656 feet) per pixel".MareKromium
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Prometheus-PIA12787.jpgGravitational Waves94 visitenessun commentoMareKromium
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Prometheus.jpgPrometheus: the "Ring-Shaper"...54 visiteCaption NASA originale:"Prometheus zooms across the Cassini spacecraft's field of view, attended by faint streamers and deep gores in Saturn's F-Ring. This frame (taken from a movie sequence of five images) shows the F-Ring shepherd moon shaping the Ring's inner edge.
Note (watching the movie) that the faint ringlet coincident with the orbit of Prometheus (only 102 Km or approx. 63 miles across) decreases sharply in brightness behind the moon in its path. The normally twisted-looking F-Ring core is overexposed in the images, causing its appearance to be more uniform than it usually is.
This image was taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 11, 2006, at a distance of approx. 2,2 MKM (about 1,4 MMs) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 162°. Image scale is roughly 13 Km (about 8 miles) per pixel".
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Prometheus.jpgPrometheus55 visitenessun commentoMareKromium
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Prometheus_and_Friends-EB.gifSingle Tone (GIF-Movie; credits: Elisabetta Bonora - Lunexit Team)54 visitenessun commentoMareKromium
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