| Piú votate - Saturn: the "Ringed Beauty" and His Moons |
Tethys-PIA11572.jpgOdysseus Crater (Natural Colors; credits: Lunexit)57 visiteCaption NASA:"The Odysseus Crater sprawls across the Mid-Latitudes of the Northern Hemisphere of the moon Tethys.
The Odysseus Crater is about 450 Km across. Lit Terrain seen here is on the anti-Saturn side of Tethys (about 1062 Km, or approx. 660 miles across). This view looks down on the moon's North Pole, which lies on the Terminator about a quarter of the way inward from the top edge of the moon in the image.
The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on July 11, 2009.
The view was acquired at a distance of approx. 577.000 Km (about 359.000 miles) from Tethys and at a Sun-Tethys-Spacecraft, or Phase, Angle of 65°.
Image scale is roughly 3 Km (a little less than 2 miles) per pixel".MareKromium
(2 voti)
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Enceladus-PIA11558.jpgEnceladus, in the distance (Natural Colors; credits: Lunexit)137 visiteCaption NASA:"The Cassini Spacecraft looks past the illuminated side of Saturn's Rings to the brilliant moon Enceladus.
Although the moon's brightness may make it appear closer to the observer, Enceladus is actually farther from the Spacecraft than the Rings in this image. As Saturn's brightest, whitest satellite, Enceladus (about 504 Km, or approx. 313 miles across) has one of the most reflective surfaces (---> Albedo) in the Solar System.
The Rings have been brightened relative to the moon to enhance visibility. This view looks toward the sunlit side of the rings from about 5° below the Ring-Plane.
The image was taken in Visible Light with the Cassini Spacecraft wide-angle camera on June 25, 2009. The view was obtained at a distance of approx. 670.000 Km (about 416.000 miles) from Enceladus and at a Sun-Enceladus-Spacecraft, or Phase, Angle of 51°.
Image scale is roughly 40 Km (about 25 miles) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11662.jpgAnother "Vertical Structure" in the "F"-Ring57 visiteCaption NASA:"As Saturn approaches its August 2009 Equinox, a shadow is cast by a narrow, vertically extended feature in the F-Ring.
Scientists are working to understand the origin of structures such as this one, but they think this image may show the shadow of an object on an inclined orbit which has punched through the F-Ring and dragged material along in its path.
The second (bottom) version of the image has been brightened to enhance the visibility of the ring and shadow. Background stars appear elongated in the image because of the camera's exposure time.
This image and others like it (see PIA11663) are only possible around the time of Saturn's Equinox which occurs every half-Saturn-year (equivalent to about 15 Earth years). The illumination geometry that accompanies Equinox lowers the Sun's angle to the Ring-Plane and causes out-of-plane structures to cast long shadows across the Rings. Cassini's cameras have spotted not only the predictable shadows of some of Saturn's moons (see PIA11657), but also the shadows of newly revealed vertical structures in the Rings themselves (see PIA11654).
This view looks toward the unilluminated side of the Rings from about 27° above the RingPlane.
The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on June 11, 2009. The view was acquired at a distance of approx. 866.000 Km (about 538.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 30°. Image scale is roughly 5 Km (a little more than 3 miles) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11663.jpgShadow of a "Vertical Structure" in the "F"-Ring61 visiteCaption NASA:"Cassini spies a shadow cast by a vertically extended structure or object in the F-Ring in this image taken as Saturn approaches its August 2009 Equinox.
The structure can be seen as a bulge near the bright core of the Ring on the right of the image. Imaging scientists are working to understand the origin of structures such as this one, but they think this image shows the shadow of what appears to be a vertically extended object in the core of the "F"-Ring.
The second (bottom) version of the image has been brightened to enhance the visibility of the Ring and shadow. Background stars appear elongated in the image because of the camera's exposure time.
This view looks toward the sunlit side of the Rings, from about 54° below the Ring-Plane.
The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on June 9, 2009. The view was obtained at a distance of approx. 592.000 Km (about 368.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 97°. Image scale is roughly 3 Km (a little less than 2 miles) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11665.jpgSmall Object in the "B"-Ring62 visiteCaption NASA:"The Cassini Spacecraft captured this image of a small object in the outer portion of Saturn's "B"-Ring casting a shadow on the Rings as Saturn approaches its August 2009 Equinox.
This new moonlet, situated about 300 miles (approx. 480 Km), inward from the outer edge of the "B"-Ring, was found by detection of its shadow which stretches 25 miles, or about 41 Km, across the Rings.
The shadow length implies the moonlet is protruding about 660 feet, or 200 meters, above the Ring-Plane.
If the moonlet is orbiting in the same plane as the ring material surrounding it, which is likely, it must be about 1300 feet, or 400 meters, across.
This object is not attended by a Propeller feature, unlike the band of moonlets discovered in Saturn's "A"-Ring earlier by Cassini (see PIA07792 and PIA06196). The "A"-Ring moonlets, which have not been directly imaged, were found because of the propeller-like narrow gaps on either side of them that they create as they orbit within the Rings. The lack of a propeller feature surrounding the new moonlet is likely because the "B"-Ring is dense, and the ring material in a dense ring would be expected to fill in any gaps around the moonlet more quickly than in a less dense region like the mid-"A"-Ring. Also, it may simply be harder in the first place for a moonlet to create propeller-like gaps in a dense ring.
Straw-like patterns of clumping ring material are also visible along the edge of the outer "B"-Ring near the right of this image. See PIA09855 to learn more about these features.
This image and others like it (see PIA11656 and PIA11659) are only possible around the time of Saturn's Equinox which occurs every half-Saturn-year (equivalent to about 15 Earth years). The illumination geometry that accompanies Equinox lowers the Sun's angle to the Ring-Plane and causes out-of-plane structures to cast long shadows across the Rings.
This view looks toward the sunlit side of the Rings from about 42° below the Ring-Plane. Background stars are visible on the right of the image. They appear elongated by the camera's exposure time.
The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on July 26, 2009. The view was obtained at a distance of approx. 296.000 Km (such as about 184.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 120°.
Image scale is roughly 1 Km (4680 feet) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11666.jpgFrom "F" to "A"!58 visiteCaption NASA:"A vertically extended Structure or Object in Saturn's "F"-Ring casts a shadow long enough to reach the "A"-Ring in this Cassini image taken just days before Planet's August 2009 Equinox.
The structure can be seen as a bulge within the bright core of the "F"-Ring on the left of the image. The structure rises far enough above the Ring-Plane for the shadow to be cast across the Roche Division and onto the "A"-Ring. The shadow is barely visible stretching across the top right quadrant of the image. The shadow appears very faint here because this view looks toward the unlit side of the Rings.
This image and others like it (see PIA11662 and PIA11663) are only possible around the time of Saturn's equinox which occurs every half-Saturn-year (equivalent to about 15 Earth years). The illumination geometry that accompanies equinox lowers the sun's angle to the ring plane and causes out-of-plane structures to cast long shadows across the Rings.
Exact equinox at Saturn begins August 11, 2009, and lasts about 4 days. Shadows have grown longer as those days draw near. Cassini's cameras have spotted not only the predictable shadows of some of Saturn's moons (see PIA11657), but also the shadows of newly revealed Vertical Structures in the Rings themselves (see PIA11654).
The "A"-Ring in the first (top) image has been brightened relative to "F"-Ring to enhance visibility of the ring and shadow. The entire image in the second (bottom) version has been contrast enhanced. Bright specks in the image are background stars.
This view looks toward the unilluminated side of the Rings from about 28° above the Ring-Plane.
The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on July 30, 2009. The view was obtained at a distance of approx. 1,8 MKM (about 1,1 MMs) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 96°.
Image scale is roughly 10 Km (a little more than 6 miles) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11545.jpgCrooked Shadow (Natural Colors; credits: Lunexit)58 visiteCaption NASA:"The shadow of the moon Mimas strikes the F-Ring at a different angle than the angle at which it is cast on the A-Ring, illustrating differences in the vertical heights of the Rings in this image taken as Saturn approaches its August 2009 Equinox.
The novel illumination geometry that accompanies Equinox lowers the Sun's angle to the Ring-Plane and causes out-of-plane structures to cast long shadows across 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.
Pan (about 28 Km, or approx. 17 miles across) orbits in the Encke Gap and is visible on the left of the image. The brightness in the lower left of the image is lens flare, a radially extending artifact that results from light being scattered within the camera optics. The shadow of Saturn cuts across the lower right of the image. Two stars can be seen through the Rings. Other bright spots in this image are also background stars.
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 wide-angle camera on June 15, 2009. The view was obtained at a distance of approx. 1,8 MKM (about 1,1 MMs) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, angle of 90°. Image scale is roughly 103 Km (about 64 miles) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11544.jpgShadows on the "B"-Ring (Natural Colors; credits: Lunar Explorer Italia)58 visiteCaption NASA:"The shadow of the moon Epimetheus stretches across the B-Ring in this image taken by Cassini as Saturn approaches its 2009 Equinox. 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.
This view looks toward the sunlit side of the rings from about 42° below the Ring-Plane.
The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on June 8, 2009. The view was obtained at a distance of approx. 700.000 Km (about 435.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 129°.
Image scale is roughly 4 Km (about 2,5 miles) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11539.jpgShadowing the "Gap"...58 visiteCaptin NASA:"The shadow of the moon Tethys is cast onto Saturn's "A"-Ring, almost blanketing the Enke Gap.
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 a movie of a moon's shadow moving across the rings, see PIA11651 and PIA11660.
This view looks toward the sunlit side of the Rings from about 29° below the Ring-Plane. The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on May 25, 2009. The view was acquired at a distance of approx. 759.000 Km (about 472.000 miles) from Saturn and at a Sun-Saturn-spacecraft, or Phase, angle of 56°.
Image scale is roughly 4 Km (about 2,5 miles) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11659.jpgShadow from the Dark Side57 visiteCaption NASA:"The shadow of Saturn's moon Tethys seems to disappear as it crosses the Planet's Rings, demonstrating variations in the density of particles across the Rings themselves.
These images, which were combined to create a mosaic and a movie, show Saturn's A-Ring on the left, the Cassini Division in the middle and dense outer B-Ring on the right.
The Cassini Spacecraft looks toward the unilluminated side of the Rings in these frames from about 49° above the Ring-Plane.
The densest parts of the B-Ring do not let much sunlight pass through to the Spacecraft's camera. Consequently, one might expect these dense areas to appear dark because they are on the Dark Side of the Rings and also because the moon's shadow is draped across them. However, these dense areas may appear brighter than expected in this geometry most likely from Saturnshine reflecting from them: denser regions should look brighter in Saturnshine than other regions. As a result, the moon's shadow appears cut off and diminished in these areas.
Seventeen images, each taken about 2' and 17" apart, were combined to create this mosaic. Contiguous images were stitched together to create the mosaic showing the whole swath of the Rings across which the moon's shadow passed. Tethys itself is not shown.
The novel illumination geometry created as the Saturnian System approaches 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 see similar movie and mosaic of Mimas' shadow moving across the unlit side of the Rings, see PIA11660.
These images have been processed, and background stars have been removed.
The images were taken in Visible Light with the Cassini Spacecraft narrow-angle camera on April 29, 2009. The view was acquired at a distance of approx. 1,3 MKM (such as about 808.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 52°.
Image scale is roughly 8 Km (about 5 miles) per pixel".MareKromium
(2 voti)
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The_Rings-PIA11658.jpgA Shadow's Traverse57 visiteCaption NASA:"Mimas' shadow traverses the sunlit side of Saturn's Rings in this mosaic showcasing the unusual sights seen at Saturn as the Planet approaches its August 2009 Equinox.
The novel illumination geometry created as the Saturnian System approaches 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.
Twenty images, each taken 3' and 36" apart, were combined to create this mosaic. Contiguous images were stitched together to create the mosaic showing the whole swath of the Rings across which the moon's shadow passed.
At the beginning of the sequence, the shadow starts on the bright B-Ring. It crosses the darker Cassini Division and then moves to the A-Ring. At the end, the edge of the shadow just catches the edge of the A-Ring, next to blackness of the Roche Division separating the A-Ring from the thin F-Ring.
These images have been processed, and background stars have been removed. To see a movie and mosaic of Mimas' shadow moving across the unlit side of the Rings, see PIA11660.
This view looks toward the sunlit side of the Rings from about 32° below the Ring-Plane. The images were taken in Visible Light with the Cassini Spacecraft narrow-angle camera on April 9, 2009. The view was obtained at a distance of approx. 1,1 MKM (such as about 684.000 miles) from Saturn and at a Sun-Saturn-Spacecraft, or Phase, Angle of 55°.
Image scale is roughly 6 Km (a little less than 4 miles) per pixel".MareKromium
(2 voti)
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Saturn-PIA11518.jpgApproaching the Equinox76 visiteCaption NASA:"The shadow of the moon Mimas has just slipped off Saturn's Rings and onto the Planet in this Cassini Spacecraft image. The shadow is visible as a short dash below the Rings' shadows on the Planet. At this exposure setting, the Rings are too dim to be seen easily. As Saturn approaches its August 2009 equinox, the Planet's moons cast shadows onto the Rings.
This view looks toward the unilluminated side of the Rings from about 61° above the Ring-Plane. 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 April 30, 2009 at a distance of approx. 1,4 MKM (about 870.000 miles) from Saturn.
Image scale is roughly 80 Km (about 50 miles) per pixel".MareKromium
(2 voti)
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