| Piú votate - Saturn: the "Ringed Beauty" and His Moons |
Saturn-PIA09854.jpgThe Southern Hemisphere of Saturn (natural colors - credits: NASA/SSI)58 visiteCaption NASA:"Saturn's Southern Hemisphere is glimpsed through the Gossamer Veil of its Rings. Ring shadows adorn the low Northern Latitudes.
This view looks toward the unilluminated side of the Rings from about 22° above the Ring-Plane. Images taken using red, green and blue spectral filters were combined to create this natural color view.
The images were acquired with the Cassini spacecraft wide-angle camera on Dec. 16, 2007 at a distance of approx. 1,5 MKM (about 908.000 miles) from Saturn.
Image scale is roughly 84 Km (approx. 52 miles) per pixel".MareKromium
(3 voti)
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Tethys-PIA09835.jpgThe Main Surface Features of Tethys54 visiteCaption NASA:"This view of Tethys displays 3 of the moon's most notable surface features. At upper left is the giant Odysseus impact basin. At lower right is the great scar of Ithaca Chasma. Extending from east to west across the moon is the great swath of terrain that appears slightly darker than the rest of the moon's surface.
This view looks toward the Saturn-facing side of Tethys (1071 Km, or approx. 665 miles across) from 33° above the Equator. North is up.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 14, 2008. The view was obtained at a distance of approx. 1,2 MKM (such as about 715.000 miles) from Tethys and at a Sun-Tethys-Spacecraft, or phase, angle of 70°.
Image scale is roughly 7 Km (about 4 miles) per pixel".MareKromium
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Saturn-PIA08396.jpgSquashed and Colourful (natural colors; credits: NASA)58 visiteCaption NASA:"Saturn in the Cassini era has proved to be an unexpectedly colorful place, compared to the browns and golds imaged by the two Voyager spacecraft. Saturn is headed toward Equinox in 2009, followed by Springtime in the Northern Hemisphere. Having a spacecraft in orbit while such changes occur will be of great benefit in scientists' quest to understand the atmospheres of the Giant Planets.
The Planet's oblate, or squashed, shape is clearly visible in this view.
The low-density Planet rotates so fast (in about 10,5 hours) that it flattens out slightly around its middle. The bluish tint of the Northern Latitudes is presumed to be a seasonal effect and will likely disappear entirely as the North receives increasingly greater amounts of sunlight.
Images taken using red, green and blue spectral filters were combined to create this natural color view.
The images were obtained with the Cassini spacecraft wide-angle camera on July 29, 2007 at a distance of approx. 3,1 MKM (about 2 MMs) from Saturn"MareKromium
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Epimetheus-N00098337.jpgEpimetheus (1)56 visiteCaption NASA:"N00098337.jpg was taken on December 03, 2007 and received on Earth December 04, 2007. The camera was pointing toward EPIMETHEUS that, at the time, was approx. 39.290 Km away, and the image was taken using the P120 and GRN filters.
This image has not been validated or calibrated".MareKromium
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The_Rings-PIA09782.jpgPrometheus' Trail57 visiteCaption NASA:"Seen here is the end result of the process that occurs every time the moon Prometheus closely approaches Saturn's F-Ring. The moon cuts a dark channel in the ring's inner edge that then shears out over successive orbits, giving the inner edge of the ring the grooved appearance seen here.
This process is described in detail, along with a movie of Prometheus creating one of the streamer/channel features, in Soft Collision.
The view is toward the sunlit side of the Rings from about 3° below the Ring-Plane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Oct. 25, 2007. The view was acquired at a distance of approx. 624.000 Km (such as about 388000 miles) from Saturn and at a Sun-Ring-Spacecraft, or phase, angle of 23°.
Image scale is roughly 3 Km (about 2 miles) per pixel".MareKromium
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Saturn-PIA09778.jpgMonitoring the Maelstrom66 visiteCaption NASA:"Clouds and vortices churn in this beautiful, close-up view of Saturn. This image is part of a series of important Cassini observations designed to provide information about winds and convection on Saturn.
The view is centered on a Region 44° North of Saturn 's Equator.
The image was taken with the Cassini spacecraft narrow-angle camera on Nov. 7, 2007 using a spectral filter sensitive to wavelengths of infrared light centered at 750 nanometers. The view was acquired at a distance of approx. 2,9 MKM (such as about 1,8 MMs) from Saturn.
Image scale is roughly 17 Km (11 miles) per pixel".MareKromium
(3 voti)
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Tethys-PIA08401.jpgThe Edge of Tethys55 visiteThe cold, cratered landscape of Saturn's moon Tethys shines in stark relief in this crescent view. Aside from its obvious aesthetic beauty, this particular Cassini mosaic was obtained mainly to understand important details about how the surface of Tethys reflects light at high phase angles (the Sun-Tethys-Spacecraft viewing angle). The beautiful interplay of light with surface topographic features is an important factor in this regard. The surface is heavily cratered, and at this oblique angle the craters give the surface a highly scalloped appearance.
Unlike some HR crescent views of Saturn's moons, this image truly gives Tethys the appearance of being composed of ice and frost. There appear to be numerous sun glints sparkling across the surface. Some of these might be specular (or mirror-like) reflections off of exposed walls of solid ice inside craters, or they might be uniformly large, frosty or icy-particle covered facets of topography that are so oriented as to give exceptionally bright but diffuse reflections.
The shadows cast by most craters in the scene are not dark, but rather, they are illuminated by light bouncing off of their sunlit walls and those of other craters. This light, which has been scattered multiple times, makes visible some details along the shadowed walls and floors of craters that would not otherwise be visible in this viewing geometry.
This mosaic was assembled from four clear filter, narrow-angle camera images, with low resolution, wide-angle camera data filling a small gap in coverage. The view is an orthographic projection and has a resolution of 211 meters (692 feet) per pixel. An orthographic view is most like the view seen by a distant observer looking through a telescope. North is up.
The view was obtained by the Cassini spacecraft on June 29, 2007, from a distance of approximately 38.000 Km (about 24.000 miles) and at a Sun-Tethys-Spacecraft, or phase, angle of 152°.
MareKromium
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Saturn-PIA08387.jpgA View from Japetus57 visiteWhile on final approach for its Sept. 2007 close encounter with Saturn's moon Japetus, Cassini spun around to take in a sweeping view of the Saturn System.
Japetus is the only major moon of Saturn with a significant inclination to its orbit. From the other major satellites, the Rings would appear nearly edge-on, but from Japetus, the Rings usually appear at a tilt, as seen here.
This natural color mosaic consists of 15 red, green and blue spectral filter images acquired in five wide-angle camera footprints that swept across the scene.
Moons visible in this image: Dione at center left, Enceladus near the left side ansa (or ring edge), Mimas is a speck against the ring shadows on Saturn's Western Limb, Rhea can be seen against the bluish backdrop of the Northern Hemisphere, Tethys is near the right ansa, and Titan near lower right.
The images were obtained on Sept. 10, 2007, at a distance of approx. 3,3 MKM (such as about 2,1 MMs) from Saturn at a Sun-Saturn-Spacecraft, or phase, angle of 33°. Image scale is about 195 Km (approx. 121 miles) per pixel on the Planet. MareKromium
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Saturn-PIA08388.jpgLooking at the Giant59 visiteSaturn sits nested in its rings of ice as Cassini once again plunges toward the graceful giant. This natural color mosaic was acquired by the Cassini spacecraft as it soared 39° above the unilluminated side of the Rings.
Little light makes its way through the Rings to be scattered in Cassini's direction in this viewing geometry, making the Rings appear somewhat dark compared to the reflective Planet. The view can be contrasted with earlier mosaics designed to showcase the Rings rather than the Planet, which were therefore given longer exposure times.
Bright clouds play in the blue-gray skies of the North. The Ring shadows continue to caress the Planet as they slide farther South toward their momentary disappearance during Equinox in 2009.
The Rings' reflected light illuminates the Southern Hemisphere on Saturn's night side.
The scene is reminiscent of the parting glance of NASA's Voyager 1 as it said goodbye to Saturn in 1981 (see PIA00335). Cassini, however, will continue to orbit Saturn for many years to come.
Three of Saturn's moons are visible in this image: Mimas (about 397 Km across) at the 2 o'clock position, Janus (about 181 Km across) at the 4 o'clock position and Pandora (about 84 Km across) at the 8 o'clock position. Pandora is a faint speck just outside the narrow F-Ring.
This mosaic was constructed from wide-angle camera images taken just before the narrow-angle camera mosaic PIA08389.
The view combines 45 images -- 15 separate sets of red, green and blue images -- taken over the course of about two hours, as Cassini scanned across the entire Main Ring System.
The images in this view were obtained on May 9, 2007, at a distance of approx. 1,1 MKM (about 700.000 miles) from Saturn.
Image scale is about 62 Km (approx. 39 miles) per pixel. MareKromium
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Saturn-PIA08390.jpgMirrors of Darkness...57 visiteOur robotic explorer Cassini regards the shadow-draped face of Saturn.
This view looks toward the unilluminated side of the Rings from about 14° above the Ring-Plane. In this viewing geometry all of the Main Rings, except for the B-Ring, appear transparent. The Rings cast their mirror image onto the Planet beyond.
Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were acquired with the Cassini spacecraft wide-angle camera on June 9, 2007, at a distance of approx. 1,6 MKM (about 972.000 miles) from Saturn.
Image scale is roughly 90 Km (about 56 miles) per pixel. MareKromium
(3 voti)
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Saturn-PIA08393.jpgThe "Opposition Effect" (again)58 visiteThe Opposition Effect, a brightness surge that is visible on Saturn's Rings when the Sun is directly behind the Spacecraft, is captured here as a colorful halo of light moving across Saturn's Sunlit Rings. The rainbow of color seen here is actually an artifact and a by-product of the spot's movement and the way the color image was produced. Cassini acquires color images by taking sequential exposures using red, green and blue spectral filters, which are then composited together to form a color view. The bright patch traveled across the Rings between exposures taken for this view, creating a series of 3 colorful spots showing its position at 3 separate moments.
This view looks toward the Sunlit side of the Rings from about 9° below the Ring-Plane.
The images in this view were acquired with the Cassini spacecraft wide-angle camera on June 12, 2007, at a distance of approx. 523.000 Km (such as about 325.000 miles) from Saturn.
Image scale is roughly 31 Km (about 19 miles) per pixel.
MareKromium
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Enceladus-PIA08385.jpgThe sources of Enceladus' Fountains59 visiteCaption NASA:"This map of the South Polar Region of Enceladus shows the correlation between jet sources identified in Cassini imaging data and hot spots on the surface located by the Composite Infrared Spectrometer Instrument.
To identify jet source locations on the surface, imaging scientists carefully measured the locations and orientations of individual jets observed along the moon's limb in Cassini images taken from multiple viewing angles. For each jet measurement, the researchers then computed a curve, or ground track, on the surface of Enceladus along which that jet might lie. The ground tracks from all of the measurements made in the various images produced many intersections on this map. By considering the jet directions at every possible intersection, the researchers isolated 8 clusters of ground track intersections as jet sources.
The 8 identified jet source locations are labeled with yellow roman numerals. Composite Infrared Spectrometer hot spots are red boxes labeled with green capital letters.
The line-of-sight intersections indicating the measurements of each source in individual images are shown as colored diamonds.
White circles indicate the uncertainty in the locations of those sets of intersections.
The map is a polar stereographic projection of Cassini imaging data.
The 4 Tiger Stripe fractures, or sulci, are labeled here.
The South Pole is the dead center on the map.
Key longitudes are also labeled around the perimeter of the map".MareKromium
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