Saturn: the "Ringed Beauty" and His Moons
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Saturn-PIA08242.jpg"Flat and Ringless" Saturn...64 visiteCaption NASA originale:"Saturn's low density and fast rotation combine to give it its characteristic oblate shape. The dramatic crescent seen here demonstrates how the Ringed Planet is much wider at the equator than at the poles.
The Rings (seem to) disappear near the center into the darkness of the Planet's shadow.
The image was taken in visible light with the Cassini spacecraft wide-angle camera on July 11, 2006 at a distance of approx. 2,9 MKM (such as about 1,8 MMs) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 163.
Image scale is approx. 169 Km (about 105 miles) per pixel".
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Saturn-PIA08250.jpgThe Rings over Saturn's Terminator74 visiteCaption NASA originale:"With Saturn's Terminator as a backdrop, this view of the unlit face of the Rings makes it easy to distinguish between areas that are actual gaps, where light passes through essentially unimpeded, and areas where the Rings block or scatter light. The gaps are regions in which the brightness varies strongly from left to right as the background goes from bright to dark.
Parts of the image are saturated at left.
The image was taken in visible light with the Cassini spacecraft wide-angle camera on July 24, 2006 at a distance of approx. 577.000 Km (such as about 359.000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 101. Image scale is roughly 31 Km (about 19 miles) per pixel".
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Saturn-PIA08252.jpgSaturnian Night63 visiteCaption NASA:"The night skies of Saturn are graced by the Planet's dazzling Rings, but as this image shows, one's view could be very different depending on the Season and from which Hemisphere one gazes up.
This point of view shows that the Southern Hemisphere is much brighter on the planet's night side than the Northern Hemisphere, owing to the brilliance of Sunlight reflecting off the Southern illuminated Rings. The Northern Hemisphere sees only the ghostly glow of the dim scattered light that manages to penetrate the Rings.
The Planet's shadow eclipses the Rings themselves in the lower half of this scene, but close inspection shows ringlets in the C-Ring silhouetted against the Southern Latitudes.
The image was taken in visible light with the Cassini spacecraft wide-angle camera on July 25, 2006 at a distance of approx. 952.000 Km (about 592.000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 124. Image scale is roughly 53 Km (about 33 miles) per pixel".
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Saturn-PIA08253.jpgThe "Ring-Masters"66 visiteCaption NASA:"This view looks down onto the unlit side of Saturn's Ringplane. It nicely shows a near-arm/far-arm brightness asymmetry in the B-Ring: The near arm of the B-Ring (in the lower half of the image) is notably darker from this viewing geometry than is the far arm (above).
Imaging scientists believe this to be a manifestation of the reflection of light from the disk of Saturn falling predominantly on the far arm of the Rings. (At the time this image was taken, Cassini was more or less on the dark side of the Planet.) As the B-Ring is the thickest part of Saturn's Rings, it scatters less sunlight from below, and reflects more Saturnshine from above, than either the A or C-Rings, making the effect look more dramatic in the B-Ring. Two small moons appear in this scene as well: Atlas and Pandora (32 and 84 Km across, respectively); between the two moons lie multiple clumps of material in the F-Ring.
The image was taken in visible light with the Cassini spacecraft wide-angle camera on July 25, 2006 at a distance of approximately 1 million kilometers (600,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 128 degrees. Image scale is 58 kilometers (36 miles) per pixel.
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Saturn-PIA08263.jpgSaturn's Terminator72 visiteCaption NASA originale:"Saturn's clouds billow and swirl in the turbulent zones of shear between Eastward- and Westward-flowing jets. This view looks toward the Terminator on Saturn, where night gives way to day.
The image was taken using a spectral filter sensitive to wavelengths of infrared light centered at 728 nanometers.
The image was obtained with the Cassini spacecraft wide-angle camera on Aug. 16, 2006 at a distance of approx. 338.000 Km (about 210.000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 67.
Image scale is roughly 17 Km (about 10 miles) per pixel".
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Saturn-PIA08265.jpgThe limb of Saturn72 visiteCaption NASA originale."Saturn's B and C-Rings disappear behind the immense Planet. Where they meet the limb, the Rings appear to bend slightly owing to upper-atmospheric refraction.
Crenulations - such as the irregularly wavy or serrated features - in the Planet's clouds denote the locations of turbulent belt/zone boundaries.
The image was taken using a spectral filter sensitive to wavelengths of infrared light centered at 728 nanometers. The view was obtained with the Cassini spacecraft wide-angle camera on Aug. 16, 2006 at a distance of approx. 256.000 Km (about 159.000 miles) from Saturn. Image scale is roughly 12 Km (about 7 miles) per pixel".
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Saturn-PIA08270.jpgNight-flight around Saturn...70 visiteCaption NASA originale:"Saturn's shadow cuts sharply across the Rings in this remarkable night side view.
The Planet's Northern Latitudes are in darkness in the upper portion of this scene, while the Southern reaches are bathed in Ringshine. On the left, Sunlight filters through the Rings, and on the right the Rings are blocking the reflected Ringshine in the shadow of Saturn. The overexposed, sunlit crescent at lower left marks the transition from Saturnian day to night.
Mimas hovers below center - a tiny bauble, ornamenting the Ringed Giant.
The image was taken in visible green light with the Cassini spacecraft wide-angle camera on August 19, 2006 at a distance of approx. 1,5 MKM (about 1 MMs) from Mimas and 1,7 MKM (about 1,1 MMs) from Saturn.
Image scale is roughly 92 Km (about 57 miles) per pixel on Mimas and approx. 103 Km (about 64 miles) on Saturn".
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Saturn-PIA08271.jpgThe "Ringed Beauty" in natural colors64 visiteCaption NASA originale:"This moody true color portrait of Saturn shows a world that can, at times, seem as serene and peaceful as it is frigid and hostile. Saturn's unlit-side Rings embrace the Planet while their shadows caress the Northern Hemisphere.
The view was obtained from about 15 above the Ring-Plane as Cassini continued its climb to higher orbital inclinations.
Images taken using red, green and blue spectral filters were combined to create this natural color view. The image was acquired with the Cassini spacecraft wide-angle camera on Aug. 18, 2006 at a distance of approximately 1,3 MKM (such as about 800.000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 137.
Image scale is roughly 76 Km (about 47 miles) per pixel".
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Saturn-PIA08272.jpgA "Clash of Clouds" in Saturn's upper atmosphere75 visiteCaption NASA originale:"The Cassini spacecraft presents a tempestuous scene in which the clouds of Saturn's bright Equatorial Region entwine with those in darker, Southerly Latitudes.
The image was taken using a filter sensitive to wavelengths of infrared light centered at 890 nanometers. The image was acquired with the Cassini spacecraft wide-angle camera on Aug. 16, 2006 at a distance of approx. 289.000 Km (about 180.000 miles) from Saturn. Image scale is roughly 14 Km (such as about 8 miles) per pixel".
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Saturn-PIA08274.jpgSaturnian turbulences...64 visiteCaption NASA originale:"With no solid land to obstruct their progress, dark vortices often roll through Saturn's Atmosphere for months or years, before merging with other vortices. On Earth, the continents usually halt the progress of large storms, like hurricanes. Vortices like these are part of the general circulation pattern of East-West flowing cloud bands, called jets, on Saturn.
The image was taken using a spectral filter sensitive to wavelengths of infrared light centered at 939 nanometers. The image was obtained with the Cassini spacecraft wide-angle camera on Aug. 16, 2006 at a distance of approximately 259.000 Km (about 161.000 miles) from Saturn. Image scale is roughly 12 Km (about 7 miles) per pixel".
Nota: quando la NASA parla di "distanza da Saturno" (come da Giove, Urano e Nettuno) essa fa convenzionalmente riferimento alla distanza che intercorre fra Sonda e "clouds' top", ovvero lo strato pi alto (e l'ultimo) di nuvole, superato il quale inizia lo spazio esterno. In caso di corpi rocciosi, invece, la distanza riferita allo spazio esistente fra Sonda e "datum" (o altitudine zero) del corpo celeste considerato.
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Saturn-PIA08282.jpgIn the darkness64 visiteSunlight filters through Saturn's Rings in sepia tones in this artful view from the Cassini spacecraft of the dark side of the Rings. Those rays from the Sun directly reflected from the lit side of the Rings onto the Planet strike and illuminate the night-side Southern Hemisphere.
The densely populated B-Ring blocks much of the Sun's light and thus looks quite dark and Tethys is a mere sliver below left.
Note that unprocessed wide-angle camera images taken in a high-phase viewing geometry generally contain stray light artifacts. These have largely been removed from this image by computer image processing.
Cassini was about 3 above the Ring-Plane when this image was obtained on Sept. 6, 2006. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were taken using the Cassini spacecraft wide-angle camera at a distance of approx. 1,8 MKM (about 1,1 MMs) from Saturn and at a phase angle of 154. Image scale is roughly 106 Km/pixel.
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Saturn-PIA08297.jpgOut of the Dark...63 visiteCaption NASA:"As Ring particles emerge from the darkness of Saturn's shadow, they pass through a region of twilight. The Sun's light, refracted by the Planet's atmosphere, peeks around the limb, followed shortly by the Sun itself.
The "penumbra" is the narrow fringe Region of the Planet's shadow where part (but not all) of the Sun is visible around the side of the Planet, creating only a partial shadow there and making the shadow edge look fuzzy.
The A and F-Rings are captured here. This view looks toward the unlit side of the Rings from about 20 above the Ring-Plane. Two faint ringlets can be seen within the Encke Gap, which stretches out of the blackness at center and toward right.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 12, 2006 at a distance of approx. 1,5 MKM (about 900.000 miles) from Saturn and at a phase angle of 163. Image scale is roughly 9 Km (about 5 miles)".
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