| Ultimi arrivi - Saturn: the "Ringed Beauty" and His Moons |
Enceladus-PIA11558.jpgEnceladus, in the distance (Natural Colors; credits: Lunexit)138 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".MareKromiumAgo 17, 2009
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Tethys-N00126733.jpgCrescent Tethys (Natural Colors; credits: Lunexit)56 visiteN00126733.jpg was taken on December 17, 2008 and received on Earth December 17, 2008. The camera was pointing toward TETHYS that, at the time, was approximately 527.571 Km away. This image was taken using the CL1 and CL2 filters and it has not been validated or calibrated.MareKromiumAgo 11, 2009
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Japetus-big.jpgJapetus (Natural Colors; credits: Lunexit)59 visiteDa "NASA - Picture of the Day", del giorno 9 Agosto 2009:"What has happened to Saturn's moon Japetus? Vast sections of this strange world are dark as coal, while others are as bright as ice. The composition of the dark material is unknown, but InfraRed Spectra indicate that it possibly contains some dark form of carbon.
Japetus also has an unusual equatorial ridge that makes it appear like a walnut. To help better understand this seemingly painted moon, NASA directed the robotic Cassini Spacecraft orbiting Saturn to swoop within 2000 Km in 2007.
Pictured above, from about 75.000 Km out, Cassini's trajectory allowed unprecedented imaging of the hemisphere of Japetus that is always trailing.
A huge impact crater seen in the South spans a tremendous 450 Km and appears superposed on an older crater of similar size. The dark material is seen increasingly coating the easternmost part of Japetus, darkening craters and highlands alike.
Close inspection indicates that the dark coating typically faces the moon's Equator and is less than a meter thick. A leading hypothesis is that the dark material is mostly dirt leftover when relatively warm but dirty ice sublimates. An initial coating of dark material may have been effectively painted on by the accretion of meteor-liberated debris from other moons.
This and other images from Cassini's Japetus flyby are being studied for even greater clues".MareKromiumAgo 11, 2009
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Prometheus-PIA11553.jpgPrometheus, its Shadow and Streamer Channel58 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".MareKromiumAgo 09, 2009
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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".MareKromiumAgo 09, 2009
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The_Rings-PIA11663.jpgShadow of a "Vertical Structure" in the "F"-Ring62 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".MareKromiumAgo 09, 2009
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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".MareKromiumAgo 09, 2009
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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".MareKromiumAgo 09, 2009
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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".MareKromiumAgo 07, 2009
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Dione-PIA11546.jpgCrescent Dione (Natural Colors; credits: Lunexit)58 visiteCaption NASA:"A large Impact Basin dominates the high Southern Latitudes of Saturn's moon Dione (see also PIA09821 to learn more from a similar image). Lit Terrain seen here is on the anti-Saturn side of Dione (such as the side that never faces Saturn). North on Dione is on the left and rotated 14° towards the upper side of the moon.
The image was taken in Visible Green Light with the Cassini Spacecraft narrow-angle camera on May 25, 2009.
The view was acquired at a distance of approx. 680.000 Km (such as about 420.000 miles) from Dione and at a Sun-Dione-Spacecraft, or Phase, Angle of 68°.
Image scale is 4 Km (about 2,5 miles) per pixel".MareKromiumAgo 03, 2009
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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".MareKromiumLug 28, 2009
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Mimas-PIA11540.jpgHighlighting Herschel Crater57 visiteCaption NASA:"The Herschel crater dominates this view of Saturn's moon Mimas. The about 130-Km, or approx. 80-mile, wide crater is located in the Middle Latitudes of Mimas.
The most brightly lit Terrain seen here - lit by the Sun - is on the Leading Hemisphere of the moon. Light reflected from Saturn dimly lights the other side of the moon.
This view is centered on terrain at 37° North Lat. and 300° West Long. The North Pole of Mimas lies on the Terminator, about a quarter of the way inward from the top of the image.
Scale in the original image was 10 Km (about 6 miles) per pixel. The image has been magnified by a factor of two and contrast-enhanced to aid visibility. The image was taken in Visible Light with the Cassini Spacecraft narrow-angle camera on June 3, 2009.
The view was obtained at a distance of approx. 1,7 MKM (about 1,1 MMs) from Mimas and at a Sun-Mimas-Spacecraft, or Phase, Angle of 119°".MareKromiumLug 26, 2009
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