Shadows of the Rings and Mimas

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

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

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

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

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

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

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

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

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

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

Mimas' Blue Streak

This enhanced-color view of Saturn's moon Mimas was made from images obtained by NASA's Cassini spacecraft. It highlights the bluish band around the icy moon's equator. The view shows the hemisphere that faces forward in Mimas' orbit around Saturn. The large round gouge on the surface is Herschel Crater.

This composite image was 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 dark, bluish band around Mimas matches 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, but the electrons appear to be zapping the Mimas surface in a way that matches the Pac-Man thermal pattern detected by Cassini's composite infrared spectrometer early in 2010.

Photo credit: NASA/JPL/SSI/LPI

Note: For a brief technical discussion about how Mimas got its blue streak, see PIA13425: Moons Under Bombardment.

Helene

Although traveling at great speed, the Cassini spacecraft managed to capture this close view of Saturn's small moon Helene during a flyby on March 3, 2010.

Saturn's atmosphere makes up the background of this composition. See PIA12653 for another image taken during this closest flyby of Helene.

This view looks toward the anti-Saturn side of Helene (33 kilometers, or 21 miles across). North on Helene is up and rotated 44 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 19,000 kilometers (12,000 miles) from Helene and at a Sun-Helene-spacecraft, or phase, angle of 25 degrees. Image scale is 113 meters (371 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Saturnian Storm Systems

This false-color image, made from infrared data obtained by NASA's Cassini spacecraft, shows dark and bright clouds on Saturn associated with thunderstorm activity. Convection generated by the storm appears to cause ammonia gas in the upper atmosphere to rise. Bright ammonia clouds, such as the s-shaped one on the right, become visible. Lightning that strikes methane in the atmosphere appears to create materials such as carbon soot and graphite. These sooty clouds appear to bloom after the bright clouds.

Scientists assigned red to show reflected sunlight from Saturn's clouds at 0.93 microns in wavelength. Green shows reflected light at 0.90 microns in wavelength, which denotes atmospheric methane absorption. Blue shows reflected sunlight from Saturn's clouds at 2.73 microns in wavelength. Dark storm clouds are unusually dark at the cloud-sensitive wavelengths designated blue and red. Boosted to higher altitudes by the energy of thunderstorms, the dark material rises to higher levels in the atmosphere where it can be seen. Saturn electrostatic discharge, a sign of lightning, was recorded in the area of the s-shaped cloud. Its lighter color suggests ammonia ice absorption from recently condensed ammonia in upwelling clouds.

The data for this image came from Cassini's visual and infrared mapping spectrometer, which can image a scene simultaneously in 352 distinct colors from 0.3 to 5.1 microns in wavelengths.

Photo credit: NASA/JPL/ASI/University of Arizona

Equinoctial Clumps

Clumps of ring material are revealed along the edge of Saturn's A ring in this image taken during the planet's August 2009 equinox.

The granular appearance of the outer edge of the A ring, first discovered soon after Cassini's orbit insertion, is likely created by gravitational clumping of particles there. As ring particles round the planet in their orbits in this particular region, they become perturbed by the gravitational forcing of Saturn's two moons, Janus and Epimetheus, whose gravitational resonance at the A ring's outer edge periodically forces the particles close together, promoting clumping (see PIA09892). The individual clumps in this image are a few kilometers across, with the largest being about 10 kilometers (6 miles).

Similar clumping is seen at the outer edge of the B ring where a resonance with Mimas has a similar effect on the ring particle orbits (see PIA11665 and PIA10421).

This view looks toward the southern side of the rings from about 18 degrees below the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on August 11, 2009. The view was acquired at a distance of approximately 190,000 kilometers (118,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 94 degrees. Image scale is 780 meters (2,560 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Coffee and Cream Clouds

Clouds in Saturn's atmosphere create an intricate pattern reminiscent of whipped cream swirling in coffee.

The view is centered on a region 15 degrees south of the planet's equator. The image was taken with the Cassini spacecraft narrow-angle camera on July 18, 2010 using a spectral filter sensitive to wavelengths of near-infrared light centered at 727 nanometers.

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 107 degrees. Image scale is 14 kilometers (9 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

The Enceladus Perrier Ocean Hypothesis

This image shows a new explanation for what feeds the mysterious jets spraying from the south polar region of Saturn's moon Enceladus: a subsurface "Perrier" ocean of slightly bubbly seawater. The new model makes sense of data previously collected by NASA's Cassini spacecraft. Cassini had detected sodium and potassium salts and carbonates indicative of a liquid, subsurface ocean. It had also found some organic particles and a large amount of heat flow over a small area. The "Perrier" ocean model appears to explain these phenomena.

This graphic is laid on top of a picture of the Enceladus jets taken by Cassini's imaging cameras in November 2009. It shows bubbles in seawater traveling through a passage in the ice crust to feed a geyser. Seawater flows back down to the subsurface ocean through cracks in the ice.

Image credit: NASA/JPL/Space Science Institute

Saturn and Rhea

A small crescent of the moon Rhea is dwarfed by the larger crescent of Saturn.

Rhea (1,528 kilometers, or 949 miles across) can be seen in the upper right 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 in visible red light with the Cassini spacecraft wide-angle camera on July 15, 2010. The view was acquired 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 98 degrees. Image scale is 153 kilometers (95 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

A-Ring Structures

Several structures in Saturn's A ring are exposed near the Encke Gap in this Cassini image.

Structure is clearly visible in the ringlets that occupy the Encke Gap in the lower right of this image. A peculiar kink can be seen in one particularly bright ringlet at the bottom right. To view vertical structures in these kinky, discontinuous ringlets casting shadows during Saturn's August 2009 equinox, see PIA11676.

Nearly uniform striations in the A ring created by the gravitational effects of the moon Pan dominate the left of this image. Saturn is out of the frame to the right. Also visible are two waves -- darker banded structures -- to the left of the Encke gap. See PIA10501 to learn more about the waves present here.

This view looks toward the southern, unilluminated side of the rings from about 18 degrees below the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 3, 2010. The view was acquired at a distance of approximately 177,000 kilometers (110,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 60 degrees. Image scale is 700 meters (2,296 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Shadowy Rings

Shadows seem ubiquitous in this Cassini spacecraft view of Saturn's rings captured shortly after the planet's August 2009 equinox.

The moon Pan (28 kilometers, or 17 miles across) casts a long shadow towards the right from where it orbits in the Encke Gap of the A ring in the upper right of the image. A structure in the thin F ring casts a short shadow on that ring in the upper left of the image. Kinky ringlets in the Encke Gap also cast many shadows in the middle and lower portions of the image, but some of those shadows appear faint.

The novel illumination geometry that accompanies equinox lowers the Sun's angle to the ringplane, significantly darkens the rings, and causes out-of-plane structures to look anomalously bright and cast shadows across the rings. These scenes are possible only during the few months before and after Saturn's equinox, which occurs only once in about 15 Earth years. Before and after equinox, 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 PIA11665).

Two background stars are visible in this image.

This view looks toward the northern, sunlit side of the rings from about 11 degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on August 19, 2009. The view was acquired 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

The Shadow of Mimas

The moon Mimas casts a shadow and creates a single blemish on the kingly crescent of Saturn.

Mimas is not shown in this view, but its shadow can be seen on the planet just north of the rings and their shadow. 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 October 25, 2009 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 2.5 million kilometers (1.6 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 116 degrees. Image scale is 144 kilometers (90 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Enceladus

At least four distinct plumes of water ice spew out from the south polar region of Saturn's moon Enceladus in this dramatically illuminated image.

Light reflected off Saturn is illuminating the surface of the moon while the Sun, almost directly behind Enceladus, is backlighting the plumes. See PIA11688 to learn more about Enceladus and its plumes.

This view looks toward the Saturn-facing side of Enceladus (504 kilometers, or 313 miles across). North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on December 25, 2009. The view was obtained at a distance of approximately 617,000 kilometers (383,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 174 degrees. Image scale is 4 kilometers (2 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Pandora

The Cassini spacecraft watches Pandora, one of the F ring's two shepherding moons, orbiting beyond the thin ring.

The small moon can be seen on the left of this image. Pandora (81 kilometers, or 50 miles across) is brightly lit on the left by sunlight on the moon's anti-Saturn side and dimly illuminated on the right by light reflected off Saturn on the moon's Saturn-facing side.

See PIA11589 to learn more about how Pandora and another moon, Prometheus, shape the F ring.

This view looks toward the northern, sunlit side of the rings from about 10 degrees above the ringplane. Seven background stars are visible.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 1, 2010. The view was obtained at a distance of approximately 1.4 million kilometers (870,000 miles) from Saturn. Image scale is 8 kilometers (5 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute