Saturn: the "Ringed Beauty" and His Moons
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Prometheus-PIA06143_modest.jpgPrometheus and the F-Ring55 visiteAs it completed its first orbit of Saturn, Cassini zoomed in on the rings to catch this wondrous view of the shepherd moon Prometheus (102 Km across) working its influence on the multi-stranded and kinked F-Ring. The F-Ring resolves into five separate strands in this closeup view. Potato-shaped Prometheus is seen here, connected to the ringlets by a faint strand of material. Imaging scientists are not sure exactly how Prometheus is interacting with the F-Ring here, but they have speculated that the moon might be gravitationally pulling material away from the ring. The ringlets are disturbed in several other places. In some, discontinuities or "kinks" in the ringlets are seen; in others, gaps in the diffuse inner strands are seen. All these features appear to be due to the influence of Prometheus. The image was taken in visible light with the narrow angle camera on Oct. 29, 2004, at a distance of about 782.000 Km from Prometheus and at a phase angle of 147°. Scale is 4.7 Km per pixel".
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Prometheus-PIA06488_modest.jpgPrometheus: one of the Ring-Masters74 visiteCaption NASA originale:"In its own way, the shepherd moon Prometheus is one of the Master of Saturn's rings. That's because the little moon maintains the inner edge of Saturn's thin, knotted, F-Ring, while its slightly smaller cohort Pandora (84 Km across) guards the ring's outer edge.
This view is a composite of nine raw images combined in a way that improves resolution and reduces noise. The final image was magnified by a factor of five.
The image clearly shows that Prometheus is not round, but instead has an oblong, potato-like shape.
The moon was discovered during the Voyager mission, and scientists then noted ridges, valleys and craters on its surface. Hints of its varied topography are present in this view, although Cassini will likely obtain much better images of Prometheus later in the mission".
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Prometheus-PIA07540.jpgThe "double night" of Prometheus55 visiteCaption NASA originale:"Saturn's moon Prometheus is seen here emerging from the darkness of Saturn's shadow. This shepherd moon, like most of Saturn's moons, always keeps the same face pointing toward the Planet. An observer on the moon's Saturn-facing side would never see the Sun directly overhead at noon, for the Planet would always be in the way (creating an eclipse). Instead, the Sun would rise in the east, but as noon approached the eclipse would begin, bringing darkness a second time. Night comes twice on Prometheus.
This image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 3, 2005, at a distance of approx. 2,1 MKM (such as 1,3 MMs) from Saturn. The image scale is 13 Km (such as 8 miles) per pixel".
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Prometheus-PIA07541.jpgPrometheus55 visiteCaption NASA originale:"Saturn's shepherd moon Prometheus hovers between the A and F-Rings as if suspended on an invisible thread, while bright clouds drift in Saturn's atmosphere approximately 130.000 Km(such as about 81.000 miles) beyond. It is noteworthy that such clouds are visible here in the shadows cast by the Rings.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 3, 2005, at a distance of approximately 2,1 MKM (1,3 MMs) from Saturn. The image scale is 13 Km (approx. 8 miles) per pixel. This view was processed to enhance fine details".
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Prometheus-PIA07549~0.jpgPrometheus from approx. 438.000 Km55 visiteCaption NASA originale:"Saturn's shepherd moon Prometheus reveals its elongated, irregular form to Cassini in this image. The moon's long axis points toward Saturn, while this view shows the southern part of the moon's anti-Saturn side (such as the face that always points away from Saturn).
The image was taken in visible red light with the Cassini spacecraft narrow-angle camera on June 7, 2005, at a distance of approx. 438.000 Km (about 272.000 miles) from Prometheus. Resolution in the original image was 3 Km per pixel. The image has been contrast-enhanced and magnified by a factor of two to aid visibility".
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Prometheus-PIA07582.jpgCrossing the Rings...54 visiteOriginal caption:"Prometheus has just passed - and gravitationally disturbed - some of the fine particulate material in the F-Ring, creating the sheared gap visible in the inner strands of the Ring. This view looks down from about 10° above the ringplane. Prometheus and the Rings are sunlit from below. At lower right lies the outermost part of the A-Ring, which grows suddenly brighter outside of the 42-Km-wide (such as about 26-miles) Keeler Gap.
The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on Aug. 2, 2005, at a distance of approximately 632.000 Km (approx. 392.000 miles) from Prometheus and at a Sun-Prometheus-spacecraft, or phase, angle of 122°. Image scale is 4 Km (about 2 miles) per pixel".
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Prometheus-PIA07601.jpgPrometheus leaves a "dark track" inside the F-Ring62 visiteOriginal caption:"Prometheus poses here with its latest creation: a dark, diagonal gore (---> incisione/striscia) in the tenuous material interior to Saturn's F-Ring. The shepherd moon creates a new gore each time it comes closest to the F-Ring while the memory of previous passes is preserved in the Rings' structure for some time afterward. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 20, 2005, at a distance of approx. 499.000 Km (about 310.000 miles) from Saturn and at a very high phase angle, such as 144°.
Resolution in the original image was 3 Km about 2 miles) per pixel".
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Prometheus-PIA07653.jpgThe Runners in the Ring: Prometheus and Pandora64 visiteThis spectacular image shows Prometheus (at left) and Pandora (at right), with their flock of icy ring particles (the F-Ring) between them. Pandora is exterior to the Ring, and closer to the spacecraft here. Each of the shepherd satellites has an unusual shape, with a few craters clearly visible.
The effect of Prometheus (about 102 Km across) on the F-Ring is visible as it pulls material out of the Ring when it is farthest from Saturn in its orbit. Pandora is about 84 Km across.
The image was taken in polarized green light with the Cassini spacecraft narrow-angle camera on Oct. 29, 2005, at a distance of approx. 459.000 Km (about 285.000 miles) from Pandora and 483.500 Km (roughly 300.500 miles) from Prometheus. The image scale is 3 Km (about 2 miles) per pixel on Pandora and 3 Km (idem) per pixel on Prometheus. The view was acquired from about 1/3 of 1° below the Ring-Plane.
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Prometheus-PIA08311.jpgPrometheus' streamers59 visiteCaption NASA:"This view shows Prometheus with a streamer it has created in the inner edge of the F-Ring. Prometheus comes close to the inner edge of the Ring once per orbit, perturbing the Ring particles there.
In 2009, the moon's orbit is expected to carry it repeatedly into the F-Ring core, an event that ring scientists are eagerly awaiting.
Prometheus is 102 Km (approx. 63 miles) across. This view looks toward the unlit side of the Rings, from about 40° above the Ring-Plane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Oct. 16, 2006 at a distance of approx. 1,8 MKM (1,1 MMs) from Prometheus and at a Sun-Prometheus-spacecraft, or phase, angle of 150°.
Scale in the original image was roughly 11 Km (about 7 miles) per pixel.
The image has been magnified by a factor of two".MareKromium
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Prometheus-PIA08847.jpgPrometheus' trail61 visiteCaption NASA:"Prometheus interacts gravitationally with the inner flanking ringlets of the F-Ring, creating dark channels as it passes.
This image was taken in a complete azimuthal scan of the Rings, during which Cassini followed Prometheus (102 Km, or 63 miles across) around the Rings for one complete orbit, or about 14 hours. This view looks toward the unlit side of the Rings from about 41° above the Ring-Plane. The moon is partly lit by Sunlight (at left) and elsewhere lit by reflected light from Saturn.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 23, 2006 at a distance of approx. 1,5 MKM (900.000 miles) from Prometheus and at a Sun-Prometheus-spacecraft, or phase, angle of 152°. Image scale is roughly 9 Km (a little more than 5 miles) per pixel".
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Prometheus-PIA08849.jpgThe "Wave-Maker"...72 visiteCaption NASA:"Prometheus dips into the inner F-Ring at its farthest point from Saturn in its orbit, creating a dark gore and a corresponding bright streamer. Gores created during previous apoapsis (the name for the farthest point in an orbit) passes, are seen above. The older gores are farther behind the moon in its orbit of Saturn. This view looks toward the unlit side of the Rings from about 31° above the Ring-Plane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 1, 2006 at a distance of approx. 1,7 MKM (about 1,1 MMs) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 162°.
Image scale is roughly 10 Km (a little more than 6 miles) per pixel".
Nota: si tratta di una elaborazione Lunexit in falsi colori che abbiamo realizzato per evidenziare non solo la reale forma di Prometheus ma anche la presenza, sia internamente, sia esternamente all'Anello "F", di una debolissima luminosità (che appare di colore rosso scuro) la quale, a nostro parere, NON è un semplice effetto ottico - tipo luce diffusa dall'Anello "F" - bensì è vero e proprio materiale: la porzione più estrema (esterna ed interna) dell'Anello "F" stesso la quale è formata, con ogni probabilità, solo da polveri.MareKromium
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Prometheus-PIA08910.jpgRestless Prometheus...64 visiteCaption NASA:"Prometheus draws a fresh streamer of material from the F-Ring as it passes the Ring's interior edge. The streamer will continuously shear out as it orbits the planet, becoming more elongated and increasingly aligned with the F-Ring with time.
A single large crater is the principle feature visible on Prometheus (102 Km, or about 63 miles across) in this view. The moon is lit partly by bright Sunlight and partly by reflected light from Saturn.
This view looks toward the unlit side of the rings from about 57° above the Ring-Plane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 11, 2007 at a distance of approx. 1,7 MKM (about 1,1 MMs) from Prometheus and at a Sun-Prometheus-spacecraft, or phase, angle of 130°.
Image scale is roughly 10 Km (about 6 miles) per pixel".
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