Saturnology

Dune Fields on Titan and Earth

2012-01-25T00:00:00.002+08:00

Two different dune fields on Titan: Belet (top left) and Fensal (bottom left), as imaged by Cassini's radar. The image also shows two similar dune fields on Earth in Rub Al Khali, Saudi Arabia.

Fensal is at higher latitude and elevation than Belet and clearly shows thinner dunes with brighter and wider areas in between, suggesting less abundant dune material in this region.

Photo credit: NASA/JPL-Caltech/ASI/ESA and USGS/ESA

Note: For more information, see Cassini's Radar Observes Titan's Tropical Dune Fields; also, PIA15225: Dune Patterns.

Mimas Behind Dione

2012-01-24T00:00:00.000+08:00

Saturn's moon Mimas peeks out from behind the night side of the larger moon Dione in this Cassini image captured during the spacecraft's December 12, 2011, flyby of Dione.

Dione is 698 miles, or 1,123 kilometers, across and its day side dominates the view on the right of the image. Smaller Mimas is on the left and measures 246 miles, or 396 kilometers, across.

Lit terrain seen here is on the Saturn-facing side of Mimas and in the area between the trailing hemisphere and anti-Saturn side of Dione. North on the moons is up and rotated 20 degrees to the right.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 58,000 miles (94,000 kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 42 degrees. Image scale is 1,833 feet (559 meters) per pixel on Dione. The view was obtained at a distance of approximately 380,000 miles (611,000 kilometers) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 41 degrees. Image scale is 2 miles (3 kilometers) per pixel on Mimas.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Closest Flyby of Dione

2012-01-17T00:00:00.001+08:00

Flying past Saturn's moon Dione, Cassini captured this view which includes two smaller moons, Epimetheus and Prometheus, near the planet's rings.

The image was taken in visible light with Cassini's narrow-angle camera during the spacecraft's flyby of Dione on December 12, 2011. This encounter was the spacecraft's closest pass of the moon's surface, but, because this flyby was intended primarily for other Cassini instruments, it did not yield Cassini's best images of the moon. Higher resolution images were obtained during earlier flybys (see PIA07638).

Dione (698 miles, or 1,123 kilometers across) is closest to Cassini here and is on the left of the image. Potato-shaped Prometheus (53 miles, or 86 kilometers across) appears above the rings near the center top of the image. Epimetheus (70 miles, or 113 kilometers across) is on the right.

This view looks toward the northern, sunlit side of the rings from less than one degree above the ring plane. The view was acquired at a distance of approximately 67,000 miles (108,000 kilometers) from Dione. Image scale is 2,122 feet (647 meters) per pixel on Dione.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan and Tethys Behind the Rings

2012-01-11T00:00:00.000+08:00

The line of Saturn's rings disrupts the Cassini spacecraft's view of the moons Tethys and Titan.

Larger Titan (3,200 miles, or 5,150 kilometers across) is on the left. Tethys (660 miles, or 1,062 kilometers across) is near the center of the image. This view looks toward the Saturn-facing sides of Tethys and Titan. The angle also shows the northern, sunlit side of the rings from less than one degree above the ring plane.

The image was taken in visible red light with the Cassini spacecraft narrow-angle camera on December 7, 2011. The view was acquired at a distance of approximately 1.4 million miles (2.2 million kilometers) from Tethys and 1.9 million miles (3.1 million kilometers) from Titan. Image scale is 8 miles (13 kilometers) per pixel on Tethys and 12 miles (19 kilometers) on Titan.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Saturn and Tethys

2012-01-03T00:00:00.001+08:00

Saturn's moon Tethys orbits in front of the wide shadows cast by the rings onto the planet for this Cassini spacecraft view.

Tethys (660 miles, or 1,062 kilometers across) appears just below the rings near the center of the image. This view looks toward the northern, sunlit side of the rings from less than one degree above the ring plane.

The image was taken with the Cassini spacecraft wide-angle camera on December 7, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 1.1 million miles (1.8 million kilometers) from Tethys. Image scale is 66 miles (107 kilometers) per pixel on Tethys.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan and Saturn

2011-12-29T00:00:00.000+08:00

The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and its rings in this true color snapshot from NASA's Cassini spacecraft.

The north polar hood can be seen on Titan (3,200 miles or 5,150 kilometers across) and appears as a detached layer at the top of the moon here. See PIA08137 and PIA09739 to learn more about Titan's atmosphere and the north polar hood.

This view looks toward the northern, sunlit side of the rings from just 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 narrow-angle camera on May 21, 2011, at a distance of approximately 1.4 million miles (2.3 million kilometers) from Titan. Image scale is 9 miles (14 kilometers) per pixel on Titan.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan and Dione

2011-12-28T00:00:00.003+08:00

Saturn's third-largest moon, Dione, can be seen through the haze of the planet's largest moon, Titan, in this view of the two posing before the planet and its rings from NASA's Cassini spacecraft.

The north polar hood can be seen on Titan appearing as a detached layer at the top of the moon here. See PIA08137 and PIA09739 to learn more about Titan's atmosphere and the north polar hood.

See PIA10560 and PIA07638 to learn more about and see a closer view of the wisps on Dione's trailing hemisphere, which appear as bright streaks here.

This view looks toward the sides of Titan (3,200 miles or 5,150 kilometers across) and Dione (698 miles or 1,123 kilometers across) facing away from Saturn. North is up on the moons. This view looks toward the northern, sunlit side of the rings from just 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 narrow-angle camera on May 21, 2011, at a distance of approximately 1.4 million miles (2.3 million kilometers) from Titan and 2 million miles (3.2 million kilometers) from Dione. Image scale is 9 miles (14 kilometers) per pixel on Titan and 12 miles (19 kilometers) on Dione.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Enceladus

2011-12-27T00:00:00.002+08:00

The Cassini spacecraft looks at a brightly illuminated Enceladus and examines the surface of the leading hemisphere of this Saturnian moon.

See PIA11685 to learn more about the surface of Enceladus. See PIA11688 to learn about the jets of water ice emanating from the moon's south polar region. North on Enceladus (313 miles across, or 504 kilometers) is up and rotated 21 degrees to the right.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on November 6, 2011. The view was obtained at a distance of approximately 67,700 miles (109,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 21 degrees. Image scale is 2,130 feet (649 meters) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan and Tethys

2011-12-26T00:00:00.000+08:00

Saturn's moon Tethys, with its stark white icy surface, peeps out from behind the larger, hazy, colorful Titan in this view of the two moons obtained by NASA's Cassini spacecraft. Saturn's rings lie between the two.

The north polar hood can be seen on Titan appearing as a detached layer at the top of the moon here. See PIA08137 and PIA09739 to learn more about Titan's atmosphere and the north polar hood.

Ithaca Chasma, a long series of scarps or cliffs on Tethys, can be seen faintly running north-south on that moon. See PIA10460 to learn more.

This view looks toward the side of Titan (3,200 miles or 5,150 kilometers across) facing away from Saturn and the side of Tethys (660 miles or 1,062 kilometers across) facing Saturn. This view looks toward the northern, sunlit side of the rings from just 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 narrow-angle camera on May 21, 2011, at a distance of approximately 1.4 million miles (2.3 million kilometers) from Titan and 2.4 million miles (3.8 million kilometers) from Tethys. Image scale is 9 miles (14 kilometers) per pixel on Titan and 18 miles (27 kilometers) per pixel on Tethys.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan and Dione in Natural Colors

2011-12-25T00:00:00.000+08:00

Saturn's largest moon, Titan, appears deceptively small paired here with Dione, Saturn's third-largest moon, in this view from NASA's Cassini spacecraft.

Titan (3,200 miles or 5,150 kilometers across) is much farther from the spacecraft than Dione (698 miles or 1,123 kilometers across) is in this view. The view was captured at a distance of approximately 684,000 miles (1.1 million kilometers) from Titan but only about 85,000 miles (136,000 kilometers) from Dione.

Titan appears in true color but has been brightened by a factor of about 1.6 relative to Dione. This view looks toward the Saturn-facing side of Titan and the area between the Saturn-facing side and leading hemisphere of Dione. North is up on the moons.

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 November 6, 2011. Scale in the original image was 5 miles (8 kilometers) per pixel on Dione and 41 miles (66 kilometers) per pixel on Titan. The image has been magnified by a factor of 1.5 and contrast-enhanced to aid visibility.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan

2011-12-24T00:00:00.001+08:00

These views from NASA's Cassini spacecraft look toward the south polar region of Saturn's largest moon, Titan, and show a depression within the moon's orange and blue haze layers near the south pole.

The close-up view was captured with the narrow-angle camera. Another view taken a second later with the wide-angle camera is also included here for context.

The moon's high altitude haze layer appears blue here whereas the main atmospheric haze is orange. The difference in color could be due to particle size of the haze. The blue haze likely consists of smaller particles than the orange haze.

The depressed or attenuated layer appears in the transition area between the orange and blue hazes about a third of the way in from the left edge of the narrow-angle image. The moon's south pole is in the upper right of this image. This view suggests Titan's north polar vortex, or hood, is beginning to flip from north to south. See PIA08137 to learn about Titan's north polar hood. To learn about changes since Saturn's August 2009 equinox, see PIA11603 and PIA11667.

The southern pole of Titan is going into darkness as the Sun advances towards the north with each passing day. The upper layer of Titan's hazes is still illuminated by sunlight.

Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were obtained on September 11, 2011 at a distance of approximately 83,000 miles (134,000 kilometers) from Titan. Image scale is 2,581 feet (787 meters) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Dione

2011-12-22T00:00:00.000+08:00

NASA's Cassini spacecraft obtained this unprocessed image on December 12, 2011. The camera was pointing toward Saturn's moon Dione from approximately 76,344 miles (122,864 kilometers) away.

Photo credit: NASA/JPL/Space Science Institute

Enceladus and Epimetheus by Saturn's Terminator

2011-12-21T00:00:00.000+08:00

A pair of Saturn's moons appear insignificant compared to the immensity of the planet in this Cassini spacecraft view along the terminator where day transitions to night.

The larger moon Enceladus (313 miles, or 504 kilometers across) is also on the left, just a bit closer to the center of the image. Epimetheus (70 miles, or 113 kilometers across) appears as a tiny black speck on the far left of the image, left of Enceladus, just below the thin line of the rings. The rings cast wide shadows on the southern hemisphere of the planet.

This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken with the Cassini spacecraft wide-angle camera on November 4, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was acquired at a distance of approximately 746,000 miles (1.2 million kilometers) from Saturn and roughly 600,000 miles (1 million kilometers) from Enceladus and Epimetheus. Image scale is about 47 miles (75 kilometers) per pixel on Saturn, 37 miles (60 kilometers) per pixel on Enceladus and 41 miles (66 kilometers) per pixel Epimetheus.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Dione

2011-12-20T00:00:00.000+08:00

NASA's Cassini spacecraft obtained this unprocessed image on December 12, 2011. The camera was pointing toward Saturn's moon Dione from approximately 69,989 miles (112,636 kilometers) away.

Photo credit: NASA/JPL/Space Science Institute

Note: I'm sorry to say, I don't know off-hand what the other two moons in this picture are.

Dione

2011-12-13T00:00:00.002+08:00

The Cassini spacecraft examines the anti-Saturnian side of Dione and shows the cratered surface east of the moon's distinctive wispy terrain.

The wispy terrain, which consists of bright cliffs on the moon's trailing hemisphere, can just barely be seen on the limb of the moon on the left of the image. North on Dione (698 miles, or 1,123 kilometers across) is up. See PIA12608 for a better view of the wisps. See PIA07769 for more southern view of Dione presented in dramatic false colors.

This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on October 2, 2011. The view was obtained at a distance of approximately 174,000 miles (280,000 kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 11 degrees. Image scale is 2 miles (3 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Mimas, Prometheus and the Rings

2011-12-07T00:00:00.002+08:00

Saturn's rings lie between a pair of moons in this Cassini spacecraft view that features Mimas and Prometheus.

Mimas (246 miles or 396 kilometers across) is the more noticeable of the two moons and is in the top left of the view. The smaller moon Prometheus (53 miles, or 86 kilometers across) is near the center of the image and is closest to Cassini. Mimas is beyond the rings and farthest from the spacecraft.

Lit terrain seen on Mimas is on the leading hemisphere of the moon. This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on November 4, 2011. The view was acquired at a distance of approximately 746,000 miles (1.2 million kilometers) from Prometheus and 870,000 miles (1.4 million kilometers) from Mimas. Image scale is 4 miles (7 kilometers) per pixel on Prometheus and 5 miles (8 kilometers) per pixel on Mimas.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Southern Enceladus in Radar View

2011-12-03T00:00:00.003+08:00

NASA's Cassini spacecraft obtained these views of the south polar area of Saturn's moon Enceladus in visible and near-visible (ultraviolet and infrared) light and synthetic-aperture radar (SAR). The region is south of 45 degrees South latitude. The SAR image, acquired November 6, 2011, is shown as an arc running from upper left to lower right, accented in light blue. Bright and dark edges of this arc are artifacts of the radar imaging process. The background image was taken with visible-light (PIA08342), with color added for emphasis (see below). Visible-light images, like we normally see in photographs, are mostly bright or dark depending on their target's chemical composition, while brightness in SAR images usually depends on how rough or smooth the surface is. The SAR swath is about 15 miles (25 kilometers) wide and is centered at 655 South latitude, 295 West longitude.

The color in the background image is used to separate different materials using ultraviolet, visible and infrared images taken from 2004 to 2009 (see PIA13423). Blue colors represent icy material that originated in the plumes and fell back to the surface. Since these images were taken using illumination by sunlight, they sense ice particles and other roughness in the wavelength range of 50 to 100 microns. The SAR swath uses microwaves 2 centimeters long in wavelength to "light" the surface, so it senses roughness in that range. In addition, the SAR may be seeing that roughness slightly under the surface.

From east-to-west (bottom right to top left), the SAR image crosses near-south-polar terrain close to many of the active sulci, which are long fissures. Throughout the scene, the surface is covered with a network of linear and near-linear grooves and fractures, interpreted to be due to extension, or pulling apart, of Enceladus' crust. These are dominated by a set of larger grooves, about a mile (kilometer) wide, running many tens of miles (kilometers) in length, and smaller grooves about 700 feet (200 meters) wide. A v-shaped region near the lower (eastern) end of the SAR swath, bounded by large faults, appears brighter to radar than most other areas, most likely the result of a rougher surface in the 2-centimeter-wavelength scale. Within, the terrain appears to be slightly more broken up, possibly the result of more dynamic tectonic forces disrupting the surface. The few-miles-wide (few-kilometers-wide) fault bounding the westernmost edge (top) edge of this area looks similar to the four active sulci that run parallel to it, suggesting that it is formed by the same processes; this feature is discussed in PIA15171. A similar fault about 1 to 2 miles (2 to 3 kilometers) wide runs along the center of much of the SAR swath for at least 47 miles (75 kilometers). Farther west still, the swath crosses another v-shaped, SAR-bright region bounded by large faults, including part of the Mosul Sulci system (see PIA15170). Once again, the network of fractures within the bright region appear to be rougher and more broken up. It also coincides with unusually colored terrain surrounding the active sulci (seen in the background images), and so possibly indicates a relatively young or active surface.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Note: For other images in this series, see PIA15170: Enceladus Sparkle and PIA15171: Groovy Enceladus.

Kraken Mare

2011-11-30T00:00:00.000+08:00

The Cassini spacecraft looks toward Saturn's largest moon, Titan, and spies the huge Kraken Mare in the moon's north.

Kraken Mare, a large sea of liquid hydrocarbons, is visible as a dark area near the top of the image. See PIA12811 and PIA11626 to learn more.

This view looks toward the Saturn-facing side of Titan (3,200 miles across, or 5,150 kilometers,). North on Titan is up and rotated 29 degrees to the left.

The image was taken with the Cassini spacecraft narrow-angle camera on September 14, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers. The view was acquired at a distance of approximately 1.2 million miles (1.9 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 26 degrees. Image scale is 7 miles (12 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Hyperion

2011-11-22T00:00:00.001+08:00

The Cassini spacecraft looks at Saturn's highly irregular moon Hyperion in this view from the spacecraft's flyby of the moon on August 25, 2011.

Hyperion (168 miles, or 270 kilometers across) has an irregular shape, and it tumbles through its orbit: that is, it does not spin at a constant rate or in a constant orientation. (A standard reference latitude-longitude system has not yet been devised for this moon.) Images such as this one extend previous coverage and allow a better inventory of the surface features, the satellite's shape and changes in its spin.

See PIA06243 and PIA07761 to learn more and to watch a movie.

The image was taken with the Cassini spacecraft narrow-angle camera using a combination of spectral filters sensitive to wavelengths of polarized green light centered at 617 and 568 nanometers. The view was obtained at a distance of approximately 36,000 miles (58,000 kilometers) from Hyperion and at a Sun-Hyperion-spacecraft, or phase, angle of 43 degrees. Image scale is 1,145 feet (349 meters) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Close-Up of Saturn's Northern Hemisphere Storm

2011-11-21T00:00:00.001+08:00

The biggest, most long-lasting Saturnian storm seen by either NASA's Cassini or Voyager spacecraft roils the atmosphere of the gas giant in this nearly true-color mosaic of Cassini images.

See PIA14903 and PIA14905 to learn more about the size and development of this storm. This mosaic shows the storm's effects encircling the planet and was created using 126 images taken in succession as different parts of Saturn's northern hemisphere rotated into Cassini's view.

Images taken using red, green and blue spectral filters are usually combined to create a natural color view. Because visible red light images were not available, images taken using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers were used in place of red. So the color is close to natural color, but is not exact.

A second version of this mosaic is also included here (Figure 1). This view uses these same nearly true color filters, but the images were contrast enhanced. The result is a view that increases the visibility of features.

The head of the storm is near the center of the mosaic, and a train of vortices appears as blue spots just to the south of the head. These blue spots are parts of the storm's tail that have already encircled the planet and are approaching from the west (left in the image). The blue color indicates they have some high, semi-transparent haze but no thick clouds underneath because there are no white- or yellow-colored clouds shown here.

This mosaic covers an area ranging from about 18 degrees north latitude to 47 degrees north latitude. The views stretch the whole longitude range, passing through 360/0 degrees west longitude near the far right of the mosaics.

The images were obtained with the Cassini spacecraft narrow-angle camera on March 6, 2011, over about 11 hours (about a Saturnian day) at a distance of approximately 2 million miles (3.3 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 83 degrees. These mosaics are simple cylindrical map projections, defined such that a square pixel subtends equal intervals of latitude and longitude. At higher latitudes, the pixel size in the north-south direction remains the same, but the pixel size (in terms of physical extent on the planet) in the east-west direction becomes smaller. The pixel size is set at the equator, where the distances along the sides are equal. This map has a pixel size of 28 miles (45 kilometers) at the equator.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Chronicling Saturn's Northern Storm

2011-11-20T00:00:00.001+08:00

This series of images from NASA's Cassini spacecraft shows the development of the largest storm seen on the planet since 1990. These true-color and composite near-true-color views chronicle the storm from its start in late 2010 through mid-2011, showing how the distinct head of the storm quickly grew large but eventually became engulfed by the storm's tail.

The earliest image of the storm, taken December 5, 2010, is in the top left of the panel. The storm appears only as a small, white cloud on the terminator between the day side and night side of the planet. See PIA14905 for a magnified view of the storm at this time.

The next view, in the top middle of the panel and taken January 2, 2011, shows that the head quickly grew much larger and a tail began to trail a great distance eastward. Some of the clouds moved south and got caught up in a current that flows to the east (to the right) relative to the storm head. In the top right of the panel, this tail, which appears as slightly blue clouds south and now west (left) of the storm head, can be seen encountering the storm in the February 25 image.

The April 22 image, in the bottom left of the panel, is one of Cassini's last views of the storm when it still had a recognizable head. In this view, the tail is south of the head and is well established by this time.

The May 18 view, in the bottom middle, shows only the storm's tail. The head still existed at this time, but it is beyond the horizon and out of the field of view here.

Between the time of the May 18 image and the next image shown here (from August 12), the head of the storm was engulfed by the part of the storm's tail that spread eastward at the same latitude as the head. The August 12 image, in the bottom right, shows that the head has lost its distinct identity and is now just part of the jumble of the storm.

Also visible in these images are several of Saturn's moons and the shadows cast onto the planet by moons. For example, the planet's second largest moon, Rhea, can be seen in the February 25 view.

The February 25 and August 12 views are true color. Images taken using red, green and blue spectral filters were combined to create these natural-color views.

The December 5, January 2, April 22 and May 18 views are nearly true color. Because a visible red light image was not available, an image taken using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers was used in place of red. So the color is close to natural color, but it is not exact.

These views were acquired at distances ranges from approximately 1.4 million miles (2.2 million kilometers) to 1.9 million miles (3.0 million kilometers) from Saturn and at Sun-Saturn-spacecraft, or phase, angles of 41 degrees to 99 degrees. All the views are set to a scale of 101 miles (162 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Note: For other pictures in this series, see PIA14901: Eleven Hours Later and PIA14902: Birth of a Behemoth Storm.

Saturn's Northern Hemisphere Storm

2011-11-19T00:00:00.001+08:00

Saturn's northern storm marches through the planet's atmosphere in the top right of this false-color mosaic from NASA's Cassini spacecraft.

See PIA14905 to learn more about this storm and watch its development over several months. Earlier in the Cassini mission, the spacecraft chronicled a smaller storm in the southern hemisphere, called the "Dragon Storm." See PIA06197 to learn more about that storm and to see a similar, false-color view.

Saturn's atmosphere and its rings are shown here in a false-color composite made from 12 images taken in near-infrared light through filters that are sensitive to varying degrees of methane absorption. Red and orange colors in this view indicate clouds that are deep in the atmosphere. Yellow and green colors, most noticeable along the top edge of the view, indicate intermediate clouds. White and blue indicate high clouds and haze. The rings appear as a thin horizontal line of bright blue because they are outside of the atmosphere and not affected by methane absorption.

This view looks toward the northern, sunlit side of the rings from just above the ring plane.

The images were taken with the Cassini spacecraft wide-angle camera using a combination of spectral filters sensitive to wavelengths of near-infrared light. The images filtered at 890 nanometers are projected as blue. The images filtered at 728 nanometers are projected as green, and images filtered at 752 nanometers are projected as red.

The images were taken on January 11, 2011, over about 50 minutes, at a distance of approximately 569,000 miles (915,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 45 degrees. The images were re-projected to the same viewing geometry, so that scale in this final mosaic is 63 miles (102 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Note: For similar images, see PIA12828: Storm Head in False Color and PIA12829: Storm Tail in False Color.

Enceladus and Epimetheus

2011-11-15T00:00:00.003+08:00

During a flyby of Saturn's moon Enceladus on October 1, 2011, the Cassini spacecraft snapped this portrait of the moon joined by its sibling Epimetheus and the planet's rings.

Enceladus (313 miles, or 504 kilometers across) takes up the center of the image, and its famous south polar jets can faintly be seen at the bottom of the image. See PIA11688 to learn more about those jets.

Epimetheus (70 miles, or 113 kilometers across) peeps into view from beyond the northern reaches of Enceladus. Lit terrain seen on Enceladus is in the area between the leading hemisphere and anti-Saturn side of the moon. North is up. This view looks toward the northern, sunlit side of the rings from just above the ringplane.

Enceladus and Epimetheus have been contrast enhanced and brightened by a factor 1.8 relative to the rings. Enceladus is closest to the spacecraft here.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 175,000 kilometers (109,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 151 degrees. Image scale is about 3,280 feet (1 kilometer) per pixel on Enceladus.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Tethys

2011-11-08T00:00:00.001+08:00

Saturn's moon Tethys shows off its tortured surface in this Cassini spacecraft image.

On the top left of the image there is huge Odysseus Crater. See PIA07693 for a closer view. On the bottom right there is Ithaca Chasma, a series of scarps that runs north-south across the moon for more than 620 miles (1,000 kilometers). North on Tethys is up and rotated 25 degrees to the right. See PIA07734 and PIA10460 to learn more.

This view looks toward the area between the leading hemisphere and Saturn-facing side of Tethys (660 miles, or 1,062 kilometers across).

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on September 14, 2011. The view was acquired at a distance of approximately 178,000 miles kilometers (287,000) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 11 degrees. Image scale is about 1 mile (2 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Hyperion

2011-11-01T00:00:00.001+08:00

The sponge-like surface of Saturn's moon Hyperion is highlighted in this Cassini portrait, captured during the spacecraft's September 16, 2011, flyby.

Hyperion (168 miles, or 270 kilometers across) has an irregular shape, and it tumbles through its orbit: that is, it does not spin at a constant rate or in a constant orientation. (A standard reference latitude-longitude system has not yet been devised for this moon.) Images such as this one extend previous coverage and allow a better inventory of the surface features, the satellite's shape and changes in its spin. See PIA06243 and PIA07761 to learn more and to watch a movie.

The image was taken in visible blue light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 55,000 miles (88,000 kilometers) from Hyperion and at a Sun-Hyperion-spacecraft, or phase, angle of 37 degrees. Image scale is 1,720 feet (524 meters) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Map of Titan - April 2011

2011-10-27T00:00:00.002+08:00

This global digital map of Saturn's moon Titan was created using images taken by the Cassini spacecraft's imaging science subsystem (ISS).

The images were taken using a filter centered at 938 nanometers, allowing researchers to examine variations in albedo (or inherent brightness) variations across the surface of Titan. Because of the scattering of light by Titan's dense atmosphere, no topographic shading is visible in these images.

The map is an equidistant projection and has a scale of 2.5 miles (4 kilometers) per pixel. Actual resolution varies greatly across the map, with the best coverage (close to the map scale) along the equator near the center of the map at 180 degrees west longitude and near the left and right edges at 0 and 360 degrees west longitude. The worst coverage is on the leading hemisphere (particularly around 120 degrees west longitude) and in some northern latitudes. Coverage in the northern polar region continues to improve as the north pole comes out of shadow after Titan's northern vernal equinox in August 2009. Large dark areas, now known to be liquid-hydrocarbon-filled lakes, have been documented at high latitudes (see PIA11146).

This map is an update to the version released in February 2009 (see PIA11149). Data from the last two years, including the most recent data in the map from April 2011, have improved coverage in the southern trailing hemisphere and over portions of the north polar region.

The mean radius of Titan used for projection of this map is 1,600 miles (2,575 kilometers). Titan is assumed to be spherical until a control network -- or model of the moon's shape based on multiple images tied together at defined points on the surface -- is created at some point in the future.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan, Dione, Pan and Pandora with Saturn's Rings

2011-10-25T00:00:00.002+08:00

A quartet of Saturn's moons, from tiny to huge, surround and are embedded within the planet's rings in this Cassini composition.

Saturn's largest moon, Titan, is in the background of the image, and the moon's north polar hood is clearly visible. See PIA08137 to learn more about that feature on Titan (3,200 miles, or 5,150 kilometers across). Next, the wispy terrain on the trailing hemisphere of Dione (698 miles, or 1,123 kilometers across) can be seen on that moon which appears just above the rings at the center of the image. See PIA10560 and PIA06163 to learn more about Dione's wisps. Saturn's small moon Pandora (50 miles, or 81 kilometers across) orbits beyond the rings on the right of the image. Finally, Pan (17 miles, or 28 kilometers across) can be seen in the Encke Gap of the A ring on the left of the image.

This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible blue light with the Cassini spacecraft narrow-angle camera on September 17, 2011. The view was obtained at a distance of approximately 1.3 million miles (2.1 million kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 27 degrees. Image scale is 8 miles (13 kilometers) per pixel on Dione.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Saturn

2011-10-20T00:00:00.002+08:00

The giant planet Saturn, as observed with the VLT NAOS-CONICA Adaptive Optics instrument on December 8, 2001; the distance was 1,209 million km. It is a composite of exposures in two near-infrared wavebands (H and K) and displays well the intricate, banded structure of the planetary atmosphere and the rings. Note also the dark spot at the south pole at the bottom of the image. One of the moons, Tethys, is visible as a small point of light below the planet. It was used to guide the telescope and to perform the adaptive optics "refocusing" for this observation. More details in the text.

This image of Saturn, the second-largest planet in the solar system, was obtained at a time when Saturn was close to summer solstice in the southern hemisphere. At this moment, the tilt of the rings was about as large as it can be, allowing the best possible view of the planet's South Pole. That area was on Saturn's night side in 1982 and could therefore not be photographed during the Voyager encounter. The dark spot close to the South Pole is a remarkable structure that measures approximately 300 km across. The bright spot close to the equator is the remnant of a giant storm in Saturn's extended atmosphere that has lasted more than 5 years.

The present photo provides what is possibly the sharpest view of the ring system ever achieved from a ground-based observatory. Many structures are visible, the most obvious being the main ring sections, the inner C-region (here comparatively dark), the middle B-region (here relatively bright) and the outer A-region, and also the obvious dark "divisions," including the well-known, broad Cassini division between the A- and B-regions, as well as the Encke division close to the external edge of the A-region and the Colombo division in the C-region. Moreover, many narrow rings can be seen at this high image resolution, in particular within the C-region.

Photo credit: ESO

Enceladus

2011-10-19T00:00:00.001+08:00

The Cassini spacecraft takes a close view of some of the southern terrain of Saturn's moon Enceladus, where newly created terrain is on display.

See PIA11685 for a mosaic of this geologically active moon's leading hemisphere that shows the more recently created terrain of the south polar region meeting older, crater-filled terrain farther north. The area shown here is between the leading hemisphere and Saturn-facing side of Enceladus (313 miles, or 504 kilometers across). This view is centered on terrain at 35 degrees south latitude, 45 degrees west longitude. North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on September 13, 2011. The view was acquired at a distance of approximately 26,000 miles (42,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 52 degrees. Image scale is 830 feet (253 meters) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Pendent Pair

2011-10-11T00:00:00.000+08:00

A pair of Saturn's moons appears as if hung below the planet's rings in this Cassini spacecraft view.

Enceladus (313 miles, or 504 kilometers across) appears just below the rings here, near the center of the image. Tethys (660 miles, or 1,062 kilometers across) is near the bottom center of the image. Tethys is closer to Cassini than is Enceladus.

This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on September 13, 2011. The view was obtained at a distance of approximately 169,000 miles (272,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 135 degrees. The view was obtained at a distance of approximately 129,000 miles (208,000 kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 135 degrees. Image scale is 10 miles (16 kilometers) per pixel on Enceladus and 7 miles (12 kilometers) per pixel on Tethys.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Enceladus

2011-10-06T00:00:00.001+08:00

NASA's Cassini spacecraft successfully completed its October 1 flyby of Saturn's moon Enceladus and its jets of water vapor and ice. At its closest approach, the spacecraft flew approximately 62 miles (100 kilometers) above the moon's surface. The close approach was designed to give some of Cassini's instruments, including the ion and neutral mass spectrometer, the chance to "taste" the jets themselves.

At a higher vantage point during the encounter, Cassini's high-resolution camera captured pictures of the jets emanating from the moon's south polar region. The latest raw images of Enceladus are online at: http://saturn.jpl.nasa.gov/photos/raw/.

The images of the surface include previously seen leading-hemisphere terrain. However, during this encounter, multi-spectral imaging of these terrains extended farther into the ultraviolet region of the electromagnetic spectrum than had previously been achieved at this resolution. By looking at the surface at ultraviolet wavelengths, scientists can better detect the difference between surface materials and shadows than they can at visible wavelengths, where icy materials are highly reflective and shadows are washed out. With both ultraviolet and visible images of the same terrain available to them, scientists will better understand how the surface coverage of icy particles coming from the vents and plumes changes with terrain type and age.

Cassini's next pass of this fascinating moon will be October 19, when the spacecraft flies by at an altitude of approximately 765 miles (1231 kilometers).

Photo credit: NASA/JPL-Caltech/Space Science Institute

Saturn's Lengthening Shadows

2011-10-05T00:00:00.002+08:00

The Cassini spacecraft watches as the shadows of Saturn's rings grow wider and creep farther south as the seasons progress from the planet's August 2009 equinox.

See PIA11667 to learn more about the changing seasons and to see a view from equinox when the rings cast only a thin shadow on Saturn's equator. See PIA09793 for an even earlier view of the rings' wide shadows draped high on the northern hemisphere.

This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken with the Cassini spacecraft wide-angle camera on August 22, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 939 nanometers. The view was acquired at a distance of approximately 252,000 miles (405,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 140 degrees. Image scale is 13 miles (21 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Shangri-La of Titan

2011-09-27T00:00:00.000+08:00

Saturn's rings lie in the distance as the Cassini spacecraft looks toward Titan and its dark region called Shangri-La, east of the landing site of the Huygens Probe.

See PIA06136 and PIA09739 and PIA08137 to learn more about Titan's atmosphere.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Rhea

2011-09-20T00:00:00.029+08:00

Southern terrain on Saturn's moon Rhea is dimly illuminated by Saturnshine in this Cassini spacecraft view of the dark side of the moon.

The spacecraft's camera is looking toward the night side of Rhea (1,528 kilometers, or 949 miles across), but sunlight reflected off the day side of immense Saturn is bright enough to illuminate the craters seen here. This view is centered on terrain at 23 degrees south latitude, 315 degrees west longitude.

Four background stars are visible.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on August 1, 2011. The view was obtained at a distance of approximately 6,000 kilometers (3,700 miles) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 113 degrees. Scale in the original image was 800 meters (2,600 feet) per pixel. The image was contrast enhanced and magnified by a factor of 1.5 to enhance the visibility of surface features.

Photo credit: NASA/JPL-Caltech/Space Science Institute

A Quintet of Moons

2011-09-13T00:00:00.045+08:00

A quintet of Saturn's moons come together in the Cassini spacecraft's field of view for this portrait.

Janus (179 kilometers, or 111 miles across) is on the far left. Pandora (81 kilometers, or 50 miles across) orbits between the A ring and the thin F ring near the middle of the image. Brightly reflective Enceladus (504 kilometers, or 313 miles across) appears above the center of the image. Saturn's second largest moon, Rhea (1,528 kilometers, or 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, or 246 miles across) can be seen beyond Rhea also on the right side of the image.

This view looks toward the northern, sunlit side of the rings from just above the ringplane. Rhea is closest to Cassini here. The rings are beyond Rhea and Mimas. Enceladus is beyond the rings.

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 29, 2011. The view was acquired at a distance of approximately 1.1 million kilometers (684,000 miles) from Rhea and 1.8 million kilometers (1.1 million miles) from Enceladus. Image scale is 7 kilometers (4 miles) per pixel on Rhea and 11 kilometers (7 miles) per pixel on Enceladus.

Photo credit: NASA/JPL-Caltech/Space Science Institute

New Crater on Titan

2011-08-30T00:00:00.000+08:00

Impact craters are rare on Titan. Until recently only seven had been identified definitely on Titan, so it was exciting when Cassini's Titan Radar Mapper imaged an eighth impact crater on June 21, 2011. This newly discovered crater is about 25 miles (40 kilometers) in diameter and is surrounded by a continuous blanket of ejecta (material thrown out from the crater) that appears bright to radar and extends roughly 10 to 12 miles (15 to 20 kilometers) beyond the rim. With its well-preserved ejecta and steep inward-facing walls, the new crater resembles the two other freshest known craters on Titan: Sinlap, seen in the radar image of February 2005 (PIA07368), and Ksa, seen in September 2006 (PIA08737) and imaged again in this latest flyby. One difference is that Sinlap and the new crater seem to have flat, largely featureless floors, but Ksa has a bright central peak.

Dunes, visible as dark lines on the left of the image, have been swept toward the crater by the winds of Titan. These dunes have encroached very little onto the bright ejecta, compared to those on Ksa where more than a third of the ejecta blanket on its western edge is covered by dunes.

While Saturn's other moons have many thousands of craters, Titan has very few. One reason is that Titan's dense atmosphere burns up the smaller impacting bodies before they can reach the surface. The craters that do form are often hard to recognize or disappear entirely as they are eroded over time by geological processes such as the wind-driven motion of sand and, possibly, icy volcanism.

This synthetic-aperture radar (SAR) image, centered at 12 degrees north latitude and 45 degrees west longitude, measures 150 miles (242 kilometers) high by 160 miles (257 kilometers) wide, with resolution of about 350 meters per pixel; north is at the top, and the image is illuminated from the bottom. Incidence angle varies from 15 to 25 degrees.

Photo credit: NASA/JPL-Caltech

Dione Above the Rings

2011-08-24T00:00:00.002+08:00

Saturn's third largest moon, Dione, appears like a solitary ornament suspended above the rings in this Cassini spacecraft view.

Lit terrain seen here is on the leading hemisphere of Dione (1,123 kilometers, or 698 miles across). North on Dione is up and rotated 1 degree to the right.

The rings are closer to Cassini in this view, with Dione more distant. This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 11, 2011. The view was obtained at a distance of approximately 3.2 million kilometers (2 million miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 85 degrees. Image scale is 19 kilometers (12 miles) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Helene

2011-08-16T00:00:00.000+08:00

Saturn's small, irregularly shaped moon Helene is strikingly illuminated in this close view captured by Cassini during the spacecraft's June 18, 2011, flyby.

Although it is not visible at this exposure, the planet actually fills the dark background of this image of Helene. See PIA12773 for another close-up from this encounter.

This view looks toward the anti-Saturn side of Helene (33 kilometers, or 21 miles across). North on Helene is up. Lit terrain on the right is on the leading hemisphere while lit terrain at the top of the image surrounds the north pole.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 11,000 kilometers (7,000 miles) from Helene and at a Sun-Helene-spacecraft, or phase, angle of 151 degrees. Image scale is 67 meters (220 feet) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Tethys and Titan

2011-08-09T00:00:00.002+08:00

The Cassini spacecraft views the cratered surface of Saturn's moon Tethys in front of the hazy orb of the planet's largest moon, Titan. Tethys (1,062 kilometers, or 660 miles across) is much closer than Titan (5,150 kilometers, or 3,200 miles across) to Cassini. This view looks toward the Saturn-facing side of Titan and toward the area between the trailing hemisphere and anti-Saturn side of Tethys. Saturn is out of the frame, far to the left.

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 14, 2011. The view was acquired at a distance of approximately 3.2 million kilometers (2 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 18 degrees. Image scale is 19 kilometers (12 miles) per pixel on Titan. The view was acquired at a distance of approximately 1.9 million kilometers (1.2 million miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 18 degrees. Image scale is 11 kilometers (7 miles) per pixel on Tethys.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Ksa Crater, Xanadu and Dunes on Titan

2011-08-04T00:00:00.001+08:00

Three of Titan's major surface features-dunes, craters and the enigmatic Xanadu-appear in this radar image from NASA's Cassini spacecraft. The hazy bright area at the left that extends to the lower center of the image marks the northwest edge of Xanadu, a continent-sized feature centered near the moon's equator. At upper right is the crater Ksa, first seen by Cassini in 2006 (PIA09172). The dark lines running between these two features are linear dunes, similar to sand dunes on Earth in Egypt and Namibia.

The dune fields on Titan, Saturn's largest moon, nearly girdle the globe at latitudes from about 30 degrees north to 30 degrees south, with the notable exception of Xanadu. In this image, the dunes overlap Xanadu only slightly. They are also more widely separated and discontinuous at the boundary, a characteristic typical of dunes on Earth where the sand supply is limited. The dunes also either wind their way around or terminate at other, smaller features, including Ksa.

Cassini's Titan Radar Mapper acquired this synthetic-aperture radar (SAR) image, centered at 11 degrees north latitude and 74 degrees west longitude, on June 21, 2011. The image covers an area 350 kilometers (217 miles) high by 930 kilometers (578 miles) wide, with resolution of about 350 meters per pixel. North is at the top, and the image is illuminated from the top. Incidence angle varies from 15 to 30 degrees.

Photo credit: NASA/JPL

Eye Toward Aegaeon

2011-08-02T00:00:00.000+08:00

The Cassini spacecraft looks toward Saturn's tiny moon Aegaeon within the G-ring arc.

The moonlet Aegaeon (formerly known as S/2008 S 1) can't be seen in this image, but it orbits in the bright arc of Saturn's faint G ring shown here. See PIA11148 to learn more.

Many background stars are visibly elongated by the motion of the spacecraft during the image's exposure. This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 4, 2011. The view was acquired at a distance of approximately 2.5 million kilometers (1.6 million miles) from Saturn. Image scale is 14 kilometers (9 miles) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Enceladus Creating Saturn's E-Ring

2011-07-26T23:20:00.000+08:00

Wispy fingers of bright, icy material reach tens of thousands of kilometers outward from Saturn's moon Enceladus into the E ring, while the moon's active south polar jets continue to fire away.

This astonishing, never-before-seen structure is made visible with the sun almost directly behind the Saturn system from Cassini's vantage point. The sun-Enceladus-spacecraft angle here is 175 degrees, a viewing geometry in which structures made of tiny particles brighten substantially.

These features are very likely the result of particles injected into Saturn orbit by the Enceladus geysers: Those injected in the direction of the moon's orbital motion end up on larger, slower orbits and trail Enceladus in its orbit, and those injected into the opposite direction end up smaller, faster orbits and lead Enceladus. (Orbital motion is counter-clockwise.) In addition, the configuration of wisps may hint at an interaction between Saturn's magnetosphere and the torrent of particles issuing from Enceladus.

In addition to the wisps, another unexpected detail is the dark gore in the center of the ring, following the moon in its orbit, likely brought about by the sweeping action of Enceladus as it orbits in the center of the E ring.

The view looks down onto Enceladus (505 kilometers, or 314 miles across) from about 15 degrees above the ringplane. Tethys (1,071 kilometers, or 665 miles across) is visible to the left of Enceladus.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on Sept. 15, 2006, at a distance of approximately 2.1 million kilometers (1.3 million miles) from Enceladus. Image scale is 128 kilometers (80 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Note: The above image is one of several used in a recent ESA press release, Herschel Confirms Enceladus as Primary Water Supply for Saturn's Atmosphere. This story is unique in that this is the first instance where a moon is directly affecting the atmosphere of the host planet.

Iapetus

2011-07-25T23:24:00.000+08:00

The Cassini spacecraft takes one of its last good looks at Iapetus, a Saturnian moon known for its yin-yang-like, bright-and-dark color pattern.

This view looks toward the south pole of Iapetus (1,471 kilometers, or 914 miles across), and lit terrain seen here is in the southern latitudes of the trailing hemisphere. There is only one other planned viewing opportunity of Iapetus left in Cassini's Solstice Mission, in March 2015.

See PIA11690 to learn more about the color on Iapetus. See PIA08404 to learn more about the moon's equatorial ridge.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 7, 2011. The view was obtained at a distance of approximately 863,000 kilometers (536,000 miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 98 degrees. Image scale is 5 kilometers (3 miles) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan's North Polar Hood

2011-07-19T00:00:00.000+08:00

The Cassini spacecraft examines Titan's north polar hood, the part of the atmosphere of Saturn's largest moon appearing dark at the top of this image.

See PIA09739 and PIA08137 to learn more about Titan's atmosphere. This view looks toward the anti-Saturn side of Titan. North on Titan (5,150 kilometers, or 3,200 miles across) is up. The southern pole of Titan is going into darkness, with the Sun advancing towards the north with each passing day. See PIA11603 and PIA11667 to learn more about the changing seasons in the Saturnian system. The upper layer of Titan's hazes is still illuminated by sunlight scattered off the planet.

The image was taken in visible violet light with the Cassini spacecraft wide-angle camera on April 19, 2011. The view was acquired at a distance of approximately 137,000 kilometers (85,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 18 degrees. Image scale is 8 kilometers (5 miles) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Updrafts of Large Ammonia Crystals in Saturn Storm

2011-05-22T00:00:00.002+08:00

This false-color infrared image, obtained by NASA's Cassini spacecraft, shows clouds of large ammonia ice particles dredged up by a powerful storm in Saturn's northern hemisphere. Large updrafts dragged ammonia gas upward more than 30 miles (50 kilometers) from below. The ammonia then condensed into large crystals in the frigid upper atmosphere. This storm is the most violent ever observed at Saturn by an orbiting spacecraft.

Cassini's visual and infrared mapping spectrometer obtained these images on Feb. 24, 2011. Scientists colorized the image by assigning red to brightness detected from the 4.08-micron wavelength, green to brightness from the 0.90-micron wavelength, and blue to brightness from the 2.73-micron wavelength. Large particles (red) reflect sunlight well at 4.08 microns. Particles at high altitude (green) reflect sunlight well at 0.9 microns. Particles comprised of ammonia -- especially large ones -- do not reflect 2.73-micron sunlight well, but instead absorb light at this wavelength.

The storm here shows up as yellow, demonstrating that it has a large signal in both red and green colors. This indicates the cloud has large particles and extends upward to relatively high altitude. In addition, the lack of blue in the feature indicates that the storm cloud has a substantial component of ammonia crystals. The head of the storm is particularly rich in such particles, as created by powerful updrafts of ammonia gas from depth in the throes of Saturn's thunderstorm.

Photo credit: NASA/JPL/Univ. of Arizona

Rhea, Dione and the Rings

2011-03-01T00:00:00.050+08:00

The Cassini spacecraft looks past the cratered south polar area of Saturn's moon Rhea to spy the moon Dione and the planet's rings in the distance.

Dione's "wispy" terrain can be seen on the trailing hemisphere of that moon. See PIA10560 to learn more.

This view looks toward the south polar area of the anti-Saturn side of Rhea (1,528 kilometers, or 949 miles across) and the Saturn-facing side of Dione (1,123 kilometers, or 698 miles across). North on the moons is up.

This view looks toward the northern, sunlit side of the rings from just above the ringplane. The rings, closer to Cassini than Dione is, obscure the view of the south of Dione.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on January 11, 2011. The view was acquired at a distance of approximately 61,000 kilometers (38,000 miles) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 15 degrees. The view was acquired at a distance of approximately 924,000 kilometers (574,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 15 degrees. Image scale is 358 meters (1,175 feet) per pixel on Rhea and 6 kilometers (4 miles) per pixel on Dione.

Photo credit: NASA/JPL/Space Science Institute

Thin Line, Broad Shadows

2011-02-22T00:00:00.002+08:00

Saturn's rings appear as only a thin line seen edge-on in the middle of this Cassini view, but the rings cast broad shadows on the southern hemisphere of the planet in the lower left of the image.

This view looks toward the southern, unilluminated side of the rings from just below the ringplane.

The image was taken with the Cassini spacecraft wide-angle camera on January 9, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 728 nanometers. The view was acquired at a distance of approximately 796,000 kilometers (494,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 147 degrees. Image scale is 44 kilometers (27 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Enceladus and Saturn's Rings

2011-01-27T21:03:00.000+08:00

The Cassini spacecraft looks over cratered and tectonically deformed terrain on Saturn's moon Enceladus as the camera also catches a glimpse of the planet's rings in the background. The image was captured during the spacecraft's flyby of Enceladus on November 30, 2010.

Geologically young terrain in the middle latitudes of the moon gives way to older, cratered terrain in the northern latitudes. See PIA11685 to learn more. This view is centered on terrain at 41 degrees north latitude, 202 degrees west longitude. North on Enceladus (504 kilometers, or 313 miles, across) is up and rotated 28 degrees to the right.

This view looks toward the northern, sunlit side of the rings from less than a degree above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 46,000 kilometers (29,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 14 degrees. Image scale is 276 meters (906 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Hyperion

2011-01-19T00:00:00.003+08:00

The Cassini spacecraft captures a view of the southern latitudes of Saturn's tumbling moon Hyperion.

To learn more about this spongy moon and how it tumbles in its orbit, see PIA06243, PIA07761 and PIA07740. Lit terrain seen here is mostly in the southern hemisphere of Hyperion (270 kilometers, or 168 miles across). The south pole of the moon is near the bottom of the illuminated terrain seen here.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on November 28, 2010. The view was obtained at a distance of approximately 80,000 kilometers (50,000 miles) from Hyperion and at a Sun-Hyperion-spacecraft, or phase, angle of 98 degrees. Image scale is 476 meters (1,562 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Dione and Enceladus

2011-01-18T00:00:00.000+08:00

On the top right of this Cassini spacecraft image, Saturn's moon Dione may appear closer to the spacecraft because it is larger than the moon Enceladus in the lower left. However, Enceladus was actually closer to the spacecraft when this image was captured.

Dione (1,123 kilometers, or 698 miles, across) is actually more than twice the size of Enceladus (504 kilometers, or 313 miles, across). Dione's bright "wispy" terrain can be seen here. See PIA10560 and PIA06163 to learn more about this terrain. This view looks toward the area between the trailing hemisphere and Saturn-facing side of Dione.

The highly reflective surface of Enceladus also stands out here. This view looks toward the trailing hemisphere of Enceladus.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on December 1, 2010. The view was acquired at a distance of approximately 510,000 kilometers (317,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 7 degrees. The view was acquired at a distance of approximately 830,000 kilometers (516,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 8 degrees. Image scale is 3 kilometers (2 miles) per pixel on Enceladus and 5 kilometers (3 miles) per pixel on Dione.

Photo credit: NASA/JPL/Space Science Institute

Enceladus

2011-01-04T00:00:00.000+08:00

Saturn's moon Enceladus brightly reflects sunlight before a backdrop of the planet's rings and the rings' shadows cast onto the planet.

The Cassini spacecraft captured this snapshot during its flyby of the moon on November 30, 2010. This view looks toward the anti-Saturn side of Enceladus (504 kilometers, or 313 miles across). North on Enceladus is up and rotated 28 degrees to the right.

This view looks toward the northern, sunlit side of the rings from less than a degree above the ringplane.

The image was taken in visible light with the Cassini spacecraft wide-angle camera. The view was obtained at a distance of approximately 53,000 kilometers (33,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 14 degrees. Image scale is 3 kilometers (2 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Rhea's Northern Craters

2010-12-28T00:26:00.000+08:00

The Cassini spacecraft captured this high-resolution view of the cratered surface of Saturn's moon Rhea as the spacecraft flew by the moon on October 17, 2010.

For closer views of Rhea's surface from earlier flybys, see PIA07765 and PIA08402. This view is centered on terrain at 60 degrees North latitude, 251 degrees West longitude on Rhea (1,528 kilometers, 949 miles across).

The image was taken in visible light with the Cassini spacecraft's narrow-angle camera. The view was acquired at a distance of approximately 40,000 kilometers (25,000 miles) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 88 degrees. Image scale is 238 meters (781 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Saturn's Plasma and Radio Waves, as Seen by Cassini

2010-12-25T23:16:00.000+08:00

This animation, derived from data obtained by NASA's Cassini spacecraft, shows how plasma swirling around Saturn is correlated to bursts of radio waves emanating from the planet. The data shown on the upper portion of the screen were obtained by the ion and neutral camera, part of the magnetospheric imaging instrument. When the plasma gets hot, it goes from red to white. The bottom part of the screen shows data from Cassini's radio and plasma wave subsystem. The data were obtained from 12:01 a.m. UTC to 11:55 a.m. UTC on October 7, 2008.

Video credit: NASA/JPL/JHUAPL/University of Iowa

Saturn's Hot Plasma Explosions

2010-12-24T20:30:00.001+08:00

This animation based on data obtained by NASA's Cassini spacecraft shows how the "explosions" of hot plasma on the night side (orange and white) periodically inflate Saturn's magnetic field (white lines). Cassini scientists have been able to compute the "pressure" that the hot plasma exerts on the surrounding magnetic field by using remote images of the previously invisible hot plasma taken by the ion and neutral camera, part of the magnetospheric imaging instrument on board Cassini.

These enormous clouds of hot plasma recur in the part of the magnetosphere known as the magnetotail roughly every 10 to 11 hours. They rotate around Saturn at a distance of about eight to 15 times the radius of Saturn. Scientists have finally been able to demonstrate that the pressure contained in these clouds is sufficient to inflate the magnetic field in a manner that is consistent with the periodic magnetic field signals that have puzzled them for so long. As the high- and low-pressure systems of atmospheric weather on Earth produce winds, pressures in space produce huge electrical currents, which in turn distort the magnetic field.

The animation is based on data that were collected from December 17 to 18, 2004.

Video credit: NASA/JPL/JHUAPL/University of Iowa

Note: For more information, see Hot Plasma Explosions Inflate Saturn's Magnetic Field.

Rhea's Western Wisps

2010-12-22T22:58:00.000+08:00

Icy fractures on Saturn's moon Rhea reflect sunlight brightly in this high-resolution mosaic created from images captured by NASA's Cassini spacecraft during its March 2, 2010, flyby. This flyby was the closest flyby of Rhea up to then.

This mosaic of six images shows the westernmost portion of the moon's "wispy" terrain. (See PIA06578 and PIA08120 to learn more.) Among the interesting features depicted here is a very straight east-west fracture near the top center of the mosaic that intersects two north-south fractures. The large crater at the bottom left of the mosaic is Inmar (55 kilometers, 34 miles across).

The closest approach of the spacecraft to Rhea during this encounter was 100 kilometers (62 miles). These images were obtained approximately half an hour later at an altitude of about 16,000 kilometers (10,000 miles).

This mosaic shows part of the side of Rhea (1528 kilometers, 949 miles across) that always faces Saturn. The images were re-projected in an orthographic projection centered on terrain at 7 degrees North latitude, 296 degrees West longitude. The mosaic itself shows terrain centered on terrain at 6 degrees North latitude, 293 degrees West longitude. North on Rhea is roughly up in the image.

The images were taken with the Cassini spacecraft narrow-angle camera. The view was obtained at a Sun-Rhea-spacecraft, or phase, angle of 2 degrees. So, Cassini was almost directly between Rhea and the Sun as it acquired these images. Image scale is 85 meters (280 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Seven Lacuna Names Approved for Use on Titan

2010-12-22T00:23:00.000+08:00

From the USGS Astrogeology Science Center:

Seven names with the descriptor term lacuna have been approved for use on Titan. For more information, see the list of Titan lacunae and the map of the north polar region of Titan in the Gazetteer of Planetary Nomenclature.

Note: The official definition of a lacuna (pl., lacunae) is an "Irregularly shaped depression on Titan having the appearance of a dry lake bed." The seven new lacunae are: Atacama Lacuna, Eyre Lacuna, Jerid Lacuna, Melrhir Lacuna, Ngami Lacuna, Racetrack Lacuna and Uyuni Lacuna.

Titan and Tethys

2010-12-21T00:00:00.000+08:00

The Cassini spacecraft watches a pair of Saturn's moons, showing the hazy orb of giant Titan beyond smaller Tethys.

In the foreground of the image, Ithaca Chasma can be seen running roughly north-south for more than 1,000 kilometers (620 miles) on Tethys. See PIA07734 for a closer view. Titan's detached, high-altitude haze layer and north polar hood are also visible here. See PIA09739 and PIA08137 to learn more.

This view looks toward the Saturn-facing sides of Titan (5,150 kilometers, or 3,200 miles across) and Tethys (1,062 kilometers, or 660 miles across).

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on October 18, 2010. The view was obtained at a distance of approximately 2.5 million kilometers (1.6 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 55 degrees. The view was obtained at a distance of approximately 1.5 million kilometers (930,000 miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 55 degrees. Image scale is 15 kilometers (9 miles) per pixel on Titan and 9 kilometers (6 miles) per pixel on Tethys.

Photo credit: NASA/JPL/Space Science Institute

Titan's Sotra Facula

2010-12-16T17:42:00.002+08:00

This movie is based on data from NASA's Cassini spacecraft and shows a flyover of an area of Saturn's moon Titan known as Sotra Facula. Scientists believe Sotra is the best case for an ice volcano -- or cryovolcano -- region on Titan.

The flyover shows two peaks more than 1,000 meters (3,000 feet) tall and multiple craters as deep as 1,500 meters (5,000 feet). It also shows finger-like flows. All of these are land features that indicate cryovolcanism. The 3-D topography comes from Cassini's radar instrument. Topography has been vertically exaggerated by a factor of 10. The false color in the initial frames shows different compositions of surface material as detected by Cassini's visual and infrared mapping spectrometer. In this color scheme, dunes tend to look relatively brown-blue. Blue suggests the presence of some exposed ice. Scientists think the bright areas have an organic coating that hides the ice and is different and lighter than the dunes. The finger-like flows appear bright yellowish-white, like the mountain and caldera. The second set of colors shows elevation, with blue being lowest and yellow and white being the highest. Dunes here appear blue because they tend to occupy low areas. The finger-like flows are harder to see in the elevation data, indicating that they are thin, maybe less than about 100 meters (300 feet) thick.

Photo credit: NASA/JPL-Caltech/USGS/University of Arizona

Notes: For a map showing Sotra Facula's location on Titan, see PIA13696: Global View of Sotra Facula, Titan. Also, this is Saturnology's 100th post!

Saturn, Rhea and Shadows

2010-12-15T01:03:00.000+08:00

Shadows adorn Saturn in this Cassini spacecraft view, which also includes the moon Rhea.

Rhea (1,528 kilometers, 949 miles across) is shown orbiting between the planet and the spacecraft and appears above the rings on the left of the image. As Saturn's northern hemisphere experiences spring, the rings now cast a shadow onto the southern hemisphere. The moon Mimas casts a small shadow on the planet south of shadows cast by the rings. The larger, elongated shadow farther south is cast by the moon Dione. Mimas and Dione are not shown.

This view looks toward the southern, unilluminated side of the rings from about 1 degree below the ringplane.

The image was taken in visible red light with the Cassini spacecraft wide-angle camera on October 22, 2010. The view was obtained at a distance of approximately 2.4 million kilometers (1.5 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 84 degrees. Image scale is 141 kilometers (88 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Dione's Erulus Crater

2010-12-07T00:12:00.002+08:00

The Cassini spacecraft snapped this shot of cratered Dione as it flew by the Saturnian moon on October 17, 2010.

The large crater at the center of the image is Erulus, which is about 120 kilometers, or 75 miles, across. This view looks toward the southern latitudes of the leading hemisphere of Dione (1,123 kilometers, or 698 miles across).

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 41,000 kilometers (25,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 53 degrees. Image scale is 240 meters (787 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Map of Tethys

2010-12-06T00:00:00.001+08:00

This global map of Saturn's moon Tethys was created using images taken by NASA's Cassini spacecraft.

This map is an update to the version released in February 2010 (see PIA12560). New data collected during Cassini's August 14, 2010, flyby of the moon are used to fill in the far northern latitudes of the map from about 75 degrees north latitude to the north pole. Coverage also improves farther south on the side of the moon facing away from Saturn. That improved coverage starts at about 40 degrees north latitude and stretches north to the pole in the area roughly west of the large Odysseus Crater (between 160 degrees and 260 degrees west longitude).

The map is an equidistant (simple cylindrical) projection and has a scale of 293 meters (960 feet) per pixel at the equator in the full size version. The mean radius of Tethys used for projection of this map is 536.3 kilometers (333.2 miles). The resolution of the map is 32 pixels per degree.

Photo credit: NASA/JPL/Space Science Institute

Note: For the polar views, click here for the northern hemisphere and here for the southern hemisphere.

Damascus Sulcus Hot Spot

2010-12-05T00:00:00.004+08:00

Data from NASA's Cassini spacecraft have enabled scientists to make the highest-resolution heat intensity maps yet for the hottest part of a "tiger stripe" fissure on Saturn's moon Enceladus. The moon's south polar region features several of these long fissures that spray water and icy particles, and the one in this image is called Damascus Sulcus.

The thermal infrared data, shown in color, come from Cassini's composite infrared spectrometer (CIRS). The grayscale background image, which is illuminated by light reflected from Saturn rather than by direct sunlight, is from Cassini's high-resolution imaging camera (ISS). The CIRS scan gives scientists confidence that the peak temperature along Damascus Sulcus, the most active tiger stripe, was about 190 Kelvin (minus 120 degrees Fahrenheit). This temperature is slightly higher than the previous maximum temperatures measured by CIRS at Damascus, which were around 170 Kelvin (minus 150 degrees Fahrenheit).

The intensity of heat radiation, measured by CIRS at wavelengths from 7 to 9 microns, is color-coded, with blue, purple, red, orange and yellow denoting progressively more intense radiation, due to higher temperatures and/or larger expanses of warm material. The image is centered near 80 degrees South latitude and 315 degrees West longitude, and covers a region about 16 kilometers (10 miles) wide. The smallest details seen in the CIRS overlay are about 800 meters (0.5 miles) in size.

The region of peak temperature is sharply bounded by the sides of the trench. Thanks to its high resolution, the CIRS map also shows for the first time that the regions on either side of the central trench are also radiating heat (shown as blue strips flanking the central multicolored strip in this image). CIRS measured temperatures of about 120 Kelvin (minus 240 degrees Fahrenheit) in the flanking regions about 400 to 1,200 meters (a quarter to three-quarters of a mile) away from the central trench.

These data were obtained on August 13, 2010 as the south pole of Enceladus began to go into winter darkness.

Photo credit: NASA/JPL/GSFC/SWRI/SSI

Geology of Tethys

2010-12-04T00:00:00.001+08:00

Geologic faults among craters on Saturn's moon Tethys are depicted in this image captured during a flyby of the moon by NASA's Cassini spacecraft on August 14, 2010.

The brightly illuminated, prominent impact crater near the bottom middle of this image has been dissected by numerous parallel faults that run diagonally across the image. The presence of the faults that cut through the crater and the movement of surface materials have made the crater outline somewhat non-circular. Near the center of the image, running diagonally from the left to right, is an old graben, or linear depression of terrain between faults. See PIA07736 and PIA07734 for images showing geologic features on Tethys taken during an earlier flyby.

Below these faults and near the middle top of the image is a large ancient impact crater that is so highly overprinted by more recent craters that it can barely be recognized.

On the left of the image, there are some horizontal lines that can be seen very faintly cutting across craters. These lines are artifacts of missing data in the raw image that could not be eliminated through processing the image.

This view looks toward the leading hemisphere of Tethys (1062 kilometers, 660 miles across). The view is centered on terrain at 59 degrees North latitude, 79 degrees West longitude.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 40,000 kilometers (25,000 miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 103 degrees. Image scale is 234 meters (767 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Enceladus Tiger Stripe Hot Spots

2010-12-03T12:00:00.003+08:00

This image shows a high-resolution heat intensity map of part of the south polar region of Saturn's moon Enceladus, made from data obtained by NASA's Cassini spacecraft.

The map reveals never-before-seen details of warm fractures that branch off like split ends from the ends of the main trenches of two "tiger stripes." The features nicknamed "tiger stripes" are long fissures that spray water vapor and icy particles. These two fissures, Cairo Sulcus (left) and Alexandria Sulcus (right), extend to the lower right, off the bottom of the image. The map also shows an intriguing isolated warm spot, shown in purple-red in the upper left of the image, that is separated from other active fissures.

The thermal data came from Cassini's composite infrared spectrometer during an August 13, 2010, flyby of Enceladus. Scientists overlaid the data on a background map of that region made from Cassini images taken in July 2005. The intensity of thermal radiation, measured at wavelengths from 12 to 16 microns, is color-coded, with dark blue, purple, red and orange denoting progressively more intense radiation, due to higher temperatures and/or larger expanses of warm material. The pale blue color indicates regions that were mapped but that were too cold to emit significant radiation. Alignment of the thermal map with the underlying base map is approximate. The map shows a region approximately 130 kilometers (80 miles) across.

These data were obtained as winter darkness began to engulf the south polar region of Enceladus. Away from the warm tiger stripes, which reach temperatures up to 190 Kelvin (minus 120 degrees Fahrenheit), Cassini measured surface temperatures near Enceladus' south pole as low as 52 Kelvin (minus 365 degrees Fahrenheit), and still colder temperatures are expected as winter advances. Scientists are still analyzing the data to calculate a temperature for the cross-cutting fractures and the isolated warm spot.

Image credit: NASA/JPL/GSFC/SWRI/SSI

Looming Enceladus

2010-12-03T00:00:00.001+08:00

Small water ice particles fly from fissures in the south polar region of Saturn's moon Enceladus in this image taken during the August 13, 2010, flyby of the moon by NASA's Cassini spacecraft.

This view looks toward the night side of Saturn, which is in the lower left of the image. Enceladus, in the top right, is closer to the spacecraft than the planet is in this view. Sunlight scatters through the planet's atmosphere and forms the bright diagonal line running from the left to bottom right of the image. The atmosphere appears layered here. Scientists think the different layers on the limb are real and not an artifact of the camera's exposure.

The famous jets, imaged by Cassini's cameras for the first time in 2005, are faintly seen here erupting from the fractures that cross the south polar region of the moon.

Illuminated terrain seen on Enceladus is on the leading hemisphere of the moon, or the side facing forward in the moon's orbit around Saturn. North on Enceladus (504 kilometers, 313 miles across) is up. The jets appear faint here, but can be seen near the center of the image. See PIA11688 to learn more.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 59,000 kilometers (37,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 155 degrees. Image scale on Enceladus is 353 meters (1,157 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Enceladus Before Saturn's Limb

2010-12-02T00:00:00.004+08:00

Jets of water ice particles spew from Saturn's moon Enceladus in this image obtained by NASA's Cassini spacecraft on August 13, 2010. A crescent of the moon appears dimly illuminated in front of the bright limb of Saturn.

This view looks toward the night side of Saturn, which occupies the lower half of the image. Enceladus, in the center of the image, is closer to the spacecraft than the planet is in this view. Sunlight scatters through the planet's atmosphere and forms the bright diagonal line running from the left to right of the image. Lit terrain seen on Enceladus (504 kilometers, 313 miles across) is on the leading hemisphere of the moon. North on Enceladus is up.

The jets erupting from the south polar region appear faint here, but can be seen at the bottom of the crescent of the moon. See PIA11688 to learn more.

The image was taken in visible light with the Cassini spacecraft wide-angle camera. The view was acquired at a distance of approximately 61,000 kilometers (38,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 155 degrees. Image scale is 4 kilometers (2 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Superimposed Craters on Rhea

2010-11-30T00:27:00.000+08:00

The two large craters on the right of this image are overprinted with smaller, more recent craters in this Cassini spacecraft view of Saturn's moon Rhea.

Rhea, at 1,528 kilometers, or 949 miles, across, is Saturn's second largest moon. This view is centered on terrain at 17 degrees South latitude, 235 degrees West longitude.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on October 17, 2010. The view was acquired at a distance of approximately 44,000 kilometers (27,000 miles) from Rhea. Image scale is 259 meters (850 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Sextet of Moons

2010-11-23T01:07:00.000+08:00

Six of Saturn's moons orbiting within and beyond the planet's rings are collected in this Cassini spacecraft image.

Enceladus (504 kilometers, or 313 miles across) is the largest moon in this image and appears at the bottom. Janus (179 kilometers, or 111 miles across) orbits beyond the rings near the center of the image. Epimetheus (113 kilometers, or 70 miles across) orbits beyond the rings near the top of the image. Atlas (30 kilometers, or 19 miles across) appears as a tiny speck between the main rings and the thin F ring on the right. Daphnis (8 kilometers, or 5 miles across), which orbits in the narrow Keeler Gap of the A ring, appears as a small, bright speck on the left of the image. Pan (28 kilometers, or 17 miles across), which orbits in the Encke Gap of the A ring, also appears as a bright speck on the left of the image. Daphnis is farther to the left of the image than Pan.

Although Enceladus appears to be in the foreground here, that moon, at a distance of 3.1 million kilometers (1.9 million miles), is actually farthest away from Cassini in this image. Janus is 3 million kilometers (1.9 million miles) from the spacecraft. The view was obtained at a distance of approximately 2.8 million kilometers (1.7 million miles) from Epimetheus.

The rings lie between Janus and Epimetheus. This view looks toward the southern, unilluminated side of the rings from about 2 degrees below the ringplane.

Enceladus is a very reflective body. To enhance visibility, the other moons and the rings have been brightened by a factor of 3.4 relative to Enceladus.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on October 6, 2010. Image scale is approximately 19 kilometers (12 miles) per pixel on Enceladus, about 18 kilometers (11 miles) per pixel on Janus and about 17 kilometers (11 miles) per pixel on Epimetheus.

Photo credit: NASA/JPL/Space Science Institute

Unexpected Chevron Structure on the Edge of Saturn's B-Ring

2010-11-19T01:26:00.000+08:00

The outer edge of Saturn's B ring exhibits an unexpected feature in this movie made from images captured by NASA's Cassini spacecraft. The images were obtained early in the planet's equinox "season" -- the period leading up to and away from August 11, 2009 when the Sun was over the planet's equator and lit the rings exactly edge on.

The B ring is shown at the top of the frame. The Cassini Division, a low-density region that separates the A and B rings, dominates the middle of the frame. The inner A ring is at the bottom.

It is apparent in the movie that the outer B ring edge location varies with time. For a more detailed view and explanation for this behavior, see PIA12794.

But, about halfway through, an unusual, 20,000-kilometer-long (12,000-mile-long), chevron-shaped structure can be seen moving along the B ring edge. Higher resolution images, taken during equinox, have shown that this region is the site of vertical structures, as tall as 3.5 kilometers (2.2 miles), whose existence was betrayed by long shadows (see PIA11668).

Cassini imaging scientists found that this chevron feature is one of two sites at the B ring's outer edge that does not follow any of the three newly discovered rotating patterns distorting the ring's edge or another pattern previously known to be caused by the moon Mimas. They have found instead that it orbits Saturn as would an independently orbiting body. As a result, scientists conclude that these are likely sites of massive bodies, or moonlets, embedded near the ring's edge but independently orbiting Saturn. In the particular region shown in this movie, the moonlets are likely big enough to cause ring material streaming past them to be excessively compressed and thrown vertically as a result. The moonlets themselves can't be seen.

This interpretation is supported by Cassini's previous discovery of a moonlet embedded in this region of the B ring (see PIA11665). The imaged moonlet, whose size is estimated at 300 meters (1,000 feet) across, was found only because it was betrayed by the shadow it cast during Saturn's August 2009 equinox period.

This view looks toward the southern, sunlit side of the rings from about 4 degrees below the ring plane.

The movie is a concatenation of 39 images taken about 2 minutes, 40 seconds apart, over the span of 1 hour, 40 minutes. The images, taken on February 25, 2009, were re-projected into the same viewing geometry.

...

The images were taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 822,000 kilometers (511,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 154 degrees. Image scale is 5 kilometers (3 miles) per pixel.

Video credit: NASA/JPL/Space Science Institute

Note: A continuous loop video of the chevron structure can be found here.

Vertical Structures in Saturn's B-Ring

2010-11-17T23:44:00.000+08:00

Vertical structures, among the tallest seen in Saturn's main rings, rise abruptly from the edge of Saturn's B ring to cast long shadows on the ring in this image taken by NASA's Cassini spacecraft two weeks before the planet's August 2009 equinox.

Part of the Cassini Division, between the B and the A rings, appears at the top of the image, showing ringlets in the inner division.

In this image, Cassini's narrow angle camera captured a 1,200-kilometer-long (750-mile-long) section arcing along the outer edge of the B ring. Here, vertical structures tower as high as 2.5 kilometers (1.6 miles) above the plane of the rings -- a significant deviation from the vertical thickness of the main A, B and C rings, which is generally only about 10 meters (about 30 feet).

Cassini scientists believe that this is one prominent region at the outer edge of the B ring where large bodies, or moonlets, up to a kilometer or more in size, are found. It is possible that these bodies significantly affect the ring material streaming past them and force the particles upward, in a "splashing" manner.

This image and others like it (see PIA11669) are only possible around the time of Saturn's equinox, which occurs every half-Saturn-year, or about every 15 Earth years. The illumination geometry that accompanies equinox lowers the Sun's angle to the ring plane and causes structures jutting out of the plane to cast long shadows across the rings. The "season" of equinox allows shadows to appear on the rings in the months before and after equinox, but the actual equinox occurred August 11, 2009, as the Sun shone directly edge-on to the ring plane.

This view looks toward the southern, sunlit side of the rings from about 32 degrees below the ring plane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 26, 2009. The view was acquired at a distance of approximately 336,000 kilometers (209,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 132 degrees. Image scale is 2 kilometers (1 mile) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Dione's "Wisps"

2010-11-16T08:37:00.000+08:00

The Cassini spacecraft looks across the surface of Saturn's moon Dione and details the "wispy" terrain first chronicled by Voyager.

This fractured terrain covers the trailing hemisphere of Dione (1,123 kilometers, or 698 miles across). See PIA10560 to learn more. This view is centered on terrain at 53 degrees north latitude, 209 degrees west longitude.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on October 17, 2010. The view was acquired at a distance of approximately 61,000 kilometers (38,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 32 degrees. Image scale is 363 meters (1,190 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Galactic Behavior for the Outer B Ring

2010-11-15T00:11:00.001+08:00

Keeping a close watch on the outer portion of Saturn's B ring, NASA's Cassini spacecraft records the complex inward and outward movement of the edge of the ring. This ring movement resembles the suspected behavior of spiral disk galaxies.

The position of the outer edge of the B ring, shown here crossing the middle of the frame, varies with time in this concatenation of 301 images taken an average of 1 minute, 50 seconds apart, over the span of about nine hours. The total variation of the edge, from the innermost to outermost locations, is 200 kilometers (120 miles). The eccentric Huygens Ringlet, another very narrow ringlet discovered by Cassini, and the innermost of the bands of ring material in the Cassini Division, a low-density region once thought to be empty, all appear in the top of the frame.

Cassini scientists have determined that the complicated radial variations in the B ring edge are caused by the presence of four scalloped patterns, all independently moving around the ring. One pattern, with two lobes, is present because of the gravitational perturbations from the moon Mimas, which alter the ring particle orbits because of a repetitive configuration of particle and satellite orbital positions known as a Lindblad resonance; this pattern always stays fixed with respect to Mimas.

The other patterns with one, two, and three lobes respectively, travel around the ring with differing speeds and are believed to be natural modes of oscillation of the ring in this vicinity, excited by a process known as "viscous overstability." In this process, the small, random motions of the ring particles feed energy into a wave that propagates outward across the ring from an inner boundary, reflects off the outer edge of the B ring (which becomes distorted as a result), and then travels inward until it reflects off the inner boundary. This continuous back-and-forth reflection is necessary for these wave patterns to grow and become visible as distortions in the outer edge of the B ring.

In supporting these so-called "self-excited" modes, the outer edge of the B ring is behaving the way astronomers believe spiral galaxies behave. However, such modes are not directly observable in galaxies. Cassini's observations of the outer B ring edge constitute the first time such large-scale modes in a broad disk of material have been observed in nature.

The movie repeats twice. The second time the movie runs, the location of the Mimas resonance (marked with a green line), the locations of the inner boundaries for the one-lobed (blue), two-lobed (yellow), and three-lobed (red) modes, and the location of the mean radius of the outer edge of the B ring (white) are all indicated.

The images were re-projected into the same viewing geometry and magnified by a factor of two to increase visibility of features. Image scale was about 2 kilometers (about 1 mile) per pixel in the original images. These images have not been cleaned of cosmic rays that struck the camera's sensor during exposure. These cosmic ray hits appear as small white streaks on the images.

The view looks toward the southern, sunlit side of the rings from about 44 degrees below the ring plane.

The images were taken in visible light with the Cassini spacecraft narrow-angle camera on January 28, 2008. The view was acquired at a distance of approximately 424,000 kilometers (264,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 52 degrees.

Video credit: NASA/JPL/Space Science Institute

Note: For a similar article and video, see PIA12795: Oscillations at B Ring Edge.

Long Spiky Shadows

2010-11-14T17:39:00.000+08:00

Vertical structures in the variable outer edge of Saturn's B ring cast shadows in these two images captured by NASA's Cassini spacecraft shortly after the planet's August 2009 northern vernal equinox.

In these two images, Cassini's narrow angle camera captured a 20,000-kilometer-long (12,000-mile-long) section arcing along the outer edge of the B ring in Saturn's rings. This particular section of the ring is known to be the site of vertical structures as tall as 3.5 kilometers (2.2 miles). See PIA11668 to learn more.

The B ring is shown at the top of both frames. The Cassini Division, a low-density ring region that separates the B ring from the A ring, runs from the bottom right to the upper left of the images. The A ring is at the bottom.

Cassini imaging scientists have concluded that this region and another in this vicinity are the sites of massive bodies, or moonlets, embedded near the ring's edge but independently orbiting Saturn. In the particular region shown in this image, the moonlets are likely big enough to cause ring material streaming past them to be excessively compressed and thrown vertically as a result.

This interpretation is supported by Cassini's previous discovery of a moonlet embedded in this region of the B ring (see PIA11665). The imaged moonlet, whose size is estimated at 300 meters (1,000 feet) across, was found only because it was betrayed by the shadow it cast during Saturn's August 2009 equinox period.

This image and others like it 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 structures jutting out of the plane 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).

Both panels were re-projected to the same viewing geometry. The right-hand panel is a mosaic of two images. The images of the right-hand panel were taken in visible light with the Cassini spacecraft narrow-angle camera on August 19, 2009. Two stars are visible.

The left-hand panel was taken in visible light with the Cassini spacecraft narrow-angle camera on August 16, 2009. One star is visible.

This view looks toward the northern, sunlit side of the rings from about 11 degrees above the ring plane at a distance of approximately 2.3 million kilometers (1.4 million miles) from Saturn. Image scale is 13 kilometers (8 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Mimas

2010-11-09T00:24:00.000+08:00

The Cassini spacecraft turns the eye of its camera toward Saturn's moon Mimas and spies the large Herschel Crater which itself looks like the iris of an eye peering out into space.

Herschel Crater is 130 kilometers, or 81 miles, wide and covers most of the right of this image. Scientists continue to study this impact basin and its surrounding terrain (see PIA12568).

Lit terrain seen here is on leading hemisphere of Mimas (396 kilometers, or 246 miles across). North on Mimas is up and rotated 1 degree to the left.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on October 16, 2010. The view was obtained at a distance of approximately 103,000 kilometers (64,000 miles) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 113 degrees. Image scale is 613 meters (2,011 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Rings Around Crescent Saturn

2010-11-02T23:50:00.000+08:00

A crescent Saturn appears nestled within encircling rings in this Cassini spacecraft image.

Clouds swirl through the atmosphere of the planet. Prometheus (86 kilometers, or 53 miles across) orbits between the main rings and the thin F ring, and this moon appears as a speck above the rings near the middle of the image.

This view looks toward the southern, unilluminated side of the rings from about 3 degrees below the ringplane.

The image was taken with the Cassini spacecraft wide-angle camera on September 14, 2010 using a spectral filter sensitive to wavelengths of near-infrared light centered at 890 nanometers. The view was obtained at a distance of approximately 2.6 million kilometers (1.6 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 100 degrees. Image scale on Saturn is 151 kilometers (94 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Shadows of the Rings and Mimas

2010-10-26T08:32:00.000+08:00

Saturn's moon Mimas casts a elliptical shadow on the planet south of the larger, wider shadows cast by the planet's rings.

Mimas and the rings are not shown here. This view looks toward the southern hemisphere of the planet.

The image was taken with the Cassini spacecraft narrow-angle camera on September 8, 2010 using a spectral filter sensitive to wavelengths of near-infrared light centered at 750 nanometers. The view was obtained at a distance of approximately 2.2 million kilometers (1.4 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 82 degrees. Image scale is 13 kilometers (8 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Rings, Rhea and Telesto

2010-10-18T21:26:00.000+08:00

This Cassini spacecraft composition features Saturn's rings, its second largest moon, Rhea, and one of the planet's tiny moons, Telesto.

Rhea (1,528 kilometers, or 949 miles across) is on the right. Telesto (25 kilometers, or 16 miles across) is near the middle of the image and appears as a bright speck. Saturn's rings are at the top of the image. The rings and Telesto have been brightened by a factor 1.6 relative to Rhea.

This view looks toward the southern, unilluminated side of the rings from just below the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on September 5, 2010. The view was acquired at a distance of approximately 1.6 million kilometers (994,000 miles) from Telesto and 1.9 million kilometers (1.2 million miles) from Rhea. Image scale is 10 kilometers (6 miles) per pixel on Telesto and 11 kilometers (7 miles) per pixel on Rhea.

Photo credit: NASA/JPL/Space Science Institute

Large Ringed Feature on Titan Named Paxsi

2010-10-16T11:53:00.000+08:00

From the USGS Astrogeology Science Center:

A large ringed feature on Titan located at 5.0N, 341.2W has been named Paxsi. For more information, see the feature page and the image of Titan in the Gazetteer of Planetary Nomenclature.

Notes: Paxsi is the goddess of the moon, education and knowledge for the Aymara people, who live in Peru, Bolivia, and Chile. The Paxsi feature is located in the Aaru region of Titan.

Titan's Cloud Coverage - July 2004-April 2010

2010-10-13T12:00:00.001+08:00

This graphic, constructed from data obtained by NASA's Cassini spacecraft, shows the percentage of cloud coverage across the surface of Saturn's moon Titan. The color scale from black to yellow signifies no cloud coverage to complete cloud coverage, over a period spanning July 2004 to April 2010.

Equinox, when the Sun shone directly over the equator, occurred in August 2009. It brought a changing of the seasons, as Titan moved out of southern summer into northern spring.

During winter in the northern hemisphere, northern polar clouds of ethane formed in Titan's troposphere, the lowest part of the atmosphere, from a constant influx of ethane and aerosols from a higher part of the atmosphere known as the stratosphere. In the southern hemisphere, atmospheric gases enriched with methane welled up from the surface to produce mid- and high-latitude clouds.

The amount and location of cloud coverage on Titan provide clues to seasonal changes on the moon. During southern summer, Cassini scientists saw a thick vortex of clouds at Titan's north pole, and a thinner patch at the south pole. Wispier mid-latitude clouds sometimes appeared in the southern temperate zones. Scientists are closely watching to see if this picture will change as northern summer approaches. They will observe whether the south polar clouds grow as the north polar clouds dissipate, and whether northern temperate clouds appear as those in the south disappear.

The data for this graphic came from Cassini's visual and infrared mapping spectrometer.

Photo credit: NASA/JPL/University of Arizona/University of Nantes/University of Paris Diderot

Clouds Clearing Around Titan's North Pole

2010-10-13T00:00:00.002+08:00

This pair of false-color images, made from data obtained by NASA's Cassini spacecraft, shows clouds covering parts of Saturn's moon Titan in yellow. Based on the way near-infrared channels of light were color-coded, cloud cover appears yellow, while Titan's hazy atmosphere appears magenta. The images show cloud cover dissolving from Titan's north polar region between May 12, 2008 (left), and December 12, 2009 (right). The clouds in the second image appear around 40 degrees south latitude, still active late after Titan's equinox.

Cassini's first observations of clouds near this latitude occurred during summer in the southern hemisphere. Equinox, when the Sun shone directly over the equator, occurred in August 2009. It brought a changing of the seasons, as Titan moved out of southern summer into northern spring.

For the past six years, Cassini has observed clouds clustered in three distinct latitude regions of Titan: large clouds at the north pole, patchy clouds at the south pole and a narrow belt around 40 degrees south. Now scientists are seeing evidence of seasonal circulation turnover at Titan. Clouds at the south pole disappeared just before equinox and the clouds in the north are thinning out. This activity agrees with models that predict cloud activity reversing from one hemisphere to another.

During winter in the northern hemisphere, northern polar clouds of ethane formed in Titan's troposphere, the lowest part of the atmosphere, from a constant influx of ethane and aerosols from a higher part of the atmosphere known as the stratosphere. In the southern hemisphere, atmospheric gases enriched with methane welled up from the surface to produce mid- and high-latitude clouds.

The data for the images was detected by Cassini's visual and infrared mapping spectrometer in near-infrared wavelengths. Scientists focused on three wavelengths of infrared radiation that were particularly good for observing cloud signatures and assigned them red, green and blue channels. Emissions in the 2 micron wavelength of light, colored red, detect the Titan surface. Emissions in the 2.11 micron wavelength, colored green, detect the lowest part of the Titan atmosphere, or troposphere. Emissions at the 2.21 micron wavelength, colored blue, detect the hazy stratosphere, a higher part of the atmosphere. The clouds appear yellowish because they lit up the channels designated red and green, but not the blue channel.

Photo credit: NASA/JPL/University of Arizona/University of Nantes/University of Paris Diderot

The Cassini Division

2010-10-12T09:31:00.000+08:00

The Cassini spacecraft looks between Saturn's A and B rings to spy structure in the Cassini Division.

The Cassini Division, occupying the middle and left of the image, contains five dim bands of ring material, but not all of the division is shown in this image. The B ring is on the right of the image. The Huygens Gap is the widest black swath near the middle of the image. See PIA11142, PIA08901 and PIA08330 to learn more. This view looks toward the northern, sunlit side of the rings from about 3 degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on September 3, 2010. The view was obtained at a distance of approximately 443,000 kilometers (275,000 miles) from Saturn. Image scale is 2 kilometers (1 mile) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Enhanced-Color Maps of Saturn's Inner Moons

2010-10-11T00:00:00.001+08:00

This set of enhanced-color maps made from data obtained by NASA's Cassini spacecraft show Saturn's moons Mimas, Enceladus, Tethys, Dione and Rhea. The global maps show the colorful splotches and bands on the icy moons' surfaces that scientists believe came from bombardments large and small.

Icy material sprayed by Enceladus, which makes up the misty E ring around Saturn, appears to leave a brighter, blue signature. The pattern of bluish material on Enceladus, for example, indicates that the moon is covered by the fallback of its own "breath."

Enceladean spray also appears to splatter the parts of Tethys, Dione and Rhea that run into the spray head-on in their orbits around Saturn. But scientists are still puzzling over why the Enceladean frost on the leading hemisphere of these moons bears a coral-colored, rather than bluish, tint.

On Tethys, Dione and Rhea, darker, rust-colored reddish hues paint the entire trailing hemisphere, or the side that faces backward in the orbit around Saturn. The reddish hues are thought to be caused by tiny particle strikes from circulating plasma, a gas-like state of matter so hot that atoms split into an ion and an electron, in Saturn's magnetic environment. Tiny, iron-rich "nanoparticles" may also be involved, based on earlier analyses by the Cassini visual and infrared mapping spectrometer team.

Mimas is touched by the tint of Enceladean spray, but it appears on the trailing side of Mimas. This probably occurs because it orbits inside the path of Enceladus, or closer to Saturn, than Tethys, Dione and Rhea.

Mimas and Tethys also sport a dark, bluish band. The bands match patterns one might expect if the surface were being irradiated by high-energy electrons that drift in a direction opposite to the flow of plasma in the magnetic bubble around Saturn. Scientists are still figuring out exactly what is happening on Mimas, but the electrons appear to be zapping the surface in a way that matches the Pac-Man pattern detected by Cassini's composite infrared spectrometer.

On Rhea, a unique chain of bluish splotches appears where fresh, bluish ice has been exposed on older crater rims. Cassini imaging scientists recently reported that they did not see evidence in Cassini images of a ring around Rhea. However, scientists analyzing these new enhanced-color maps suggest the crash of orbiting material, perhaps a ring, to the surface of Rhea in the not too distant past, could explain the bluish splotches.

These new maps were made by processing raw images obtained by Cassini's imaging cameras from 2004 to 2009. Scientists analyzed frames shot through visible-light, ultraviolet and infrared filters. The processing enhanced our views of these moons beyond what could be seen by the human eye.

The maps are in a simple cylindrical projection from 90 degrees south latitude (bottom) to 90 degrees north latitude (top). From left to right, they cover 360 degrees west longitude to minus 2 degrees west longitude. The leading hemisphere appears on the right side of each map and trailing hemisphere appears on the left.

Photo credit: NASA/JPL/SSI/LPI

Tinted Rhea

2010-10-10T12:47:00.002+08:00

These three views of Saturn's moon Rhea were made from data obtained by NASA's Cassini spacecraft, enhanced to show colorful splotches and bands on the icy moon's surface. Scientists believe the reddish and bluish tints came from bombardments large and small.

Icy material sprayed by the moon Enceladus hits Rhea head-on in its orbit around Saturn and leaves a coral-colored tint. Darker, rust-colored reddish hues paint the trailing hemisphere, or the side that faces backward in the moon's orbit around Saturn. The reddish hues are thought to be caused by tiny particle strikes from circulating plasma, a gas-like state of matter so hot that atoms split into an ion and an electron, in Saturn's magnetic environment. Tiny, iron-rich "nanoparticles" may also be involved, based on earlier analyses by the Cassini visual and infrared mapping spectrometer team.

Rhea sports a chain of bluish splotches along the equator that appear where fresh, bluish ice has been exposed on older crater rims. Cassini imaging scientists recently reported that they did not see evidence in Cassini images of a ring around Rhea. However, scientists analyzing these enhanced-color views suggest the bluish material could have been exposed by the crash of orbiting material -- perhaps a ring -- to the surface of Rhea in the not too distant past.

These images were made by processing raw images obtained by Cassini's imaging cameras in November 2005. Scientists analyzed frames shot through visible-light, ultraviolet and infrared filters. The processing enhanced our views of these moons beyond what could be seen by the human eye.

The image on the left shows a composite image made from data in the infrared, green and ultraviolet filters. The middle view shows an image made from data analyzing the ratio of infrared to green wavelengths, indicating the relative redness of the features. The brighter the feature is in this middle view, the redder it is. The image on the right shows data analyzing the ratio of infrared to ultraviolet wavelengths. The darker the feature is, the bluer the tint

In each of these images, the trailing hemisphere is on the left side and leading hemisphere is on the right side. They are centered near 145 degrees west longitude, about 35 degrees east of the boundary between the leading and trailing hemispheres. The bright crater Inktomi can be seen near the center of the images on the left and right, but was more difficult to see in the middle image because of there is less contrast in the infrared/ultraviolet ratio.

Photo credit: NASA/JPL/SSI/LPI

Note: For a brief technical discussion about how Rhea got its tints, see PIA13425: Moons Under Bombardment.

Rhea and Titan

2010-10-09T00:00:00.000+08:00

A darkly defined Rhea passes before the fuzzy orb of Titan in this Cassini view of Saturn's two largest moons.

Rhea is closer to the spacecraft in this view. See PIA09895 to learn more about Rhea. See PIA08137 to learn more about Titan's atmosphere.

Lit terrain seen here is on the Saturn-facing sides of Rhea (1,528 kilometers, or 949 miles across) and Titan (5,150 kilometers, or 3,200 miles across).

The image was taken in visible blue light with the Cassini spacecraft narrow-angle camera on November 19, 2009. The view was acquired at a distance of approximately 1.1 million kilometers (684,000 miles) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 118 degrees. The view was acquired at a distance of approximately 2.3 million kilometers (1.4 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 118 degrees. Image scale is 7 kilometers (4 miles) per pixel on Rhea and 14 kilometers (9 miles) on Titan.

Photo credit: NASA/JPL/Space Science Institute

Epimetheus

2010-10-08T12:00:00.001+08:00

Swinging by Saturn's small moon Epimetheus, Cassini snapped this shot during the spacecraft's April 7, 2010, flyby.

See PIA09813 and PIA06226 for even closer views from earlier flybys. Lit terrain seen here is on the Saturn-facing side of Epimetheus (113 kilometers, or 70 miles across). North on Epimetheus is up and rotated 27 degrees to the left.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 87,000 kilometers (54,000 miles) from Epimetheus and at a Sun-Epimetheus-spacecraft, or phase, angle of 69 degrees. Image scale is 519 meters (1,703 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute