Crescent Mimas

A thin sliver of Mimas is illuminated, the long shadows showing off its many craters, indicators of the moon's violent history.

The most famous evidence of a collision on Mimas (246 miles, or 396 kilometers across) is the crater Herschel that gives Mimas its Death Star-like appearance. See PIA12568 for more on Herschel.

This view looks toward the anti-Saturn hemisphere of Mimas. North on Mimas is up and rotated 40 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 20, 2013.

The view was acquired at a distance of approximately 100,000 miles (200,000 kilometers) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 130 degrees. Image scale is 4,000 feet (1 kilometer) per pixel.

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

Tethys

Tethys, like many moons in the solar system, keeps one face pointed towards the planet around which it orbits. Tethys' anti-Saturn face is seen here, fully illuminated, basking in sunlight. On the right side of the moon in this image is the huge crater Odysseus.

The Odysseus crater is 280 miles (450 kilometers) across while Tethys is 660 miles (1,062 kilometers) across. See PIA07693 for a closer view and more information on the Odysseus crater.

This view looks toward the anti-Saturn side of Tethys. North on Tethys is up and rotated 33 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 15, 2013.

The view was acquired at a distance of approximately 503,000 miles (809,000 kilometers) from Tethys. Image scale is 3 miles (5 kilometers) per pixel.

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

Dione

When imaged with the Sun nearly at our backs, Dione's heavily scarred surface lacks the shadows that emphasize the surface topography. However, this geometry highlights variations in surface brightness, which provide further evidence of Dione's active and often violent past.

The surface of Dione (698 miles, or 1,123 kilometers across) is covered in craters, reminding us of the impacts that have shaped all of the worlds of our solar system. Dione's surface also bears linear features that suggest geological activity in the past. See PIA07638 for more information.

Lit terrain seen here is on the Saturn-facing hemisphere of Dione. North on Dione is up and rotated 33 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 27, 2013.

The view was obtained at a distance of approximately 810,000 miles (1.3 million kilometers) from Dione. Image scale is 5 miles (8 kilometers) per pixel.

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

Dione

Dione's large crater, Evander, appears here half in shadow, throwing its topography into sharp relief. Evander is centered at about 57 degrees South latitude, 145 degrees West longitude and can also be seen in the Dione south polar map featured in PIA12579 (see also PIA12728).

Lit terrain seen here is on the anti-Saturn hemisphere of Dione. North on Dione is up and rotated 25 degrees to the left. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on August 22, 2013.

The view was acquired at a distance of approximately 870,000 miles (1.4 million kilometers) from Dione. Image scale is 5 miles (8 kilometers) per pixel.

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

Tethys

Tethys' trailing side shows two terrains that tell a story of a rough past. To the north (up, in the image) is older, rougher terrain, while to the south is new material dubbed "smooth plains" by scientists.

The smooth plains are roughly antipodal to the large impact crater Odysseus. Odysseus, which is on the far side of Tethys (660 miles, or 1,060 kilometers across) from this perspective, is out of view. (See PIA12588 for a view of Odysseus.) It's thought that the impact that created Odysseus also created the smooth plains, although exactly how this happened is not yet clear.

This view looks toward the trailing hemisphere of Tethys. North on Tethys is up and rotated 2 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on November 27, 2013.

The view was obtained at a distance of approximately 1.1 million miles (1.8 million kilometers) from Tethys. Image scale is 7 miles (11 kilometers) per pixel.

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

Tethys

The craters of Tethys tell the story of a violent history marked by impacts. The names of the craters also tell oft-violent stories: in this case, the Iliad and the Odyssey. Here, we see the craters Melanthius (near the center, at the day/night terminator), Dolius (above Melanthius), and Penelope (upper left almost over the limb). Penelope was the faithful and wise wife of the Greek hero Odysseus, Dolius was their loyal gardener, and Melanthius was Dolius' son.

This view looks toward the leading side of Tethys. North on Tethys is up and rotated 32 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 16, 2013.

The view was obtained at a distance of approximately 684,000 miles (1.1 million kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 63 degrees. Image scale is 4 miles (7 kilometers) per pixel. The image has been zoomed in by a factor of 1.5.

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

Quintet of Moons

Five moons pose for the international Cassini spacecraft to create this beautiful portrait with Saturn’s rings.

This view, from 29 July 2011, looks toward the northern, sunlit side of the rings from just above the ringplane.

At the far right, and obscuring Saturn itself, is the planet’s second largest moon Rhea, which spans 1528 km. Rhea is closest to Cassini in this composition, at a distance of 1.1 million kilometers. Its heavily cratered surface bears witness to a violent history, with many craters overlapping or erasing the traces of older impact events.

The nearly 400 km-wide Mimas lies just beyond, and seemingly levitates just above Saturn’s innermost rings. The outline of the moon’s large, distinguishing crater Herschel is partially covered by Rhea, but can just be made out along with numerous smaller craters.

Brightly reflective Enceladus appears above the center of the image and lies beyond the rings, at a distance of 1.8 million kilometers from Cassini. Although not visible in this image, icy Enceladus is covered with a network of frozen ridges and troughs, with plumes of ice particles jetting from fissures in its southern hemisphere.

To the lower left, tiny Pandora, just 81 km across, appears skewered by Saturn’s outer rings – in fact, it orbits between the planet’s A and F rings.

Last but not least, the irregularly shaped Janus lies at the far left of the image, several shadowy surface markings corresponding to large impact craters.

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

Dione

Like their semi-divine namesakes, Dione's twin craters Romulus and Remus (just above-right of center) stand together. Dido, the larger crater featuring a central peak, lies just to the southeast on the day/night terminator.

Lit terrain seen here is on the Saturn-facing hemisphere of Dione. North on Dione is up. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 28, 2013.

The view was obtained at a distance of approximately 870,000 miles (1.4 million kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 77 degrees. Image scale is 5 miles (8 kilometers) per pixel in the original image. This image has been zoomed in by a factor of 1.5 to enhance clarity.

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

Abisme Crater

From the USGS Astrogeology Science Center:

The IAU Working Group for Planetary System Nomenclature has approved the name Abisme for a crater on Iapetus. For more information, see the map of Iapetus in the Gazetteer of Planetary Nomenclature.

Iapetus

These two global images of Iapetus show the extreme brightness dichotomy on the surface of this peculiar Saturnian moon. The left-hand panel shows the moon's leading hemisphere and the right-hand panel shows the moon's trailing side. While low and mid latitudes of the leading side exhibit a surface almost as dark as charcoal, broad tracts of the trailing side are almost as bright as snow. The dark terrain covers about 40 percent of the surface and is named Cassini Regio. The names of the bright terrain are Roncevaux Terra (north) and Saragossa Terra (south).

On both hemispheres, the dominant landforms are impact craters. The largest known well-preserved basin on Iapetus, called Turgis, has a diameter of about 580 kilometers (360 miles). It lies at 17 degrees north latitude, 28 degrees west longitude at the eastern edge of the dark Cassini Regio and is visible on the right side of the left-hand panel. The prominent basin on the southern trailing side (at the lower left of the right-hand panel) is Engelier. Engelier is located at 41 degrees south latitude, 265 degrees west longitude, and has a diameter of about 504 kilometers (313 miles). Its formation destroyed about half of Gerin, another large basin on Iapetus. Gerin is located at 46 degrees south latitude, 233 degrees west longitude, and has a diameter of about 445 kilometers (276 miles). Tortelosa Montes, a part of the giant equatorial ridge that was discovered in Cassini images on December 25, 2004, is visible in the left panel as a thin line within Cassini Regio, and as a tall prominence at the western limb. It continues onto the trailing side (right side of right panel), where the bright western flanks of the Carcassone Montes appear as dominant bright spots within the western edge of Cassini Regio.

The cause of the extreme brightness dichotomy on Iapetus is likely to be thermal segregation of water ice on a global scale. Thermal effects are usually expected to act latitudinally. That is, polar areas are colder than equatorial terrain in most cases due to the more oblique angle of the solar irradiation. Therefore, an additional process is required to explain the longitudinal difference as well. In one model, dark, reddish dust coming in from space and preferentially deposited on the leading side forms a small, but crucial difference between the leading and trailing hemispheres, which is sufficient to allow the thermal effect to evaporate the water ice on the leading side completely, but only marginally on the trailing side. See PIA11689 to learn more. Iapetus' extremely slow rotation rate (1,904 hours), its distance from the sun, its relatively small size and surface gravity, and its outer position within the regular satellite system of Saturn are also crucial contributing conditions for this mechanism to work as observed.

North on Iapetus is approximately up in the images. Iapetus has a diameter of 1471 kilometers (914 miles).

The right-hand panel, released previously as PIA08384, shows a mosaic of 60 different images, obtained on September 10, 2007.

The left-hand panel is a color composite of three images obtained through infrared, green and ultraviolet spectral filters (centered at 752, 568 and 338 nanometers, respectively) by Cassini's narrow-angle camera on December 27, 2004. The view was acquired at a distance of approximately 717,000 kilometers (446,000 miles) from Iapetus and at a sun-Iapetus-spacecraft, or phase, angle of 22 degrees.

Scale in the original image on the left was about 4 kilometers (2.5 miles) per pixel. For ease of comparison, the scales in both the left and right images were set to 1,400 meters (4,600 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Note: For more information, see Saturn is Like an Antiques Shop, Cassini Suggests.

Rhea

The surface of Saturn's moon Rhea bears witness to its violent history. Each crater seen here records an impact in the moon's past.

On some of Rhea's terrains, craters are so densely packed that they lie on top of each other, newer impacts often erasing the older craters. Rhea is 949 miles, or 1,528 kilometers across.

This view is centered on terrain at 38 degrees north latitude, 290 degrees west longitude. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on December 22, 2012.

The view was acquired at a distance of approximately 19,000 miles (31,000 kilometers) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 30 degrees. Image scale is 600 feet (183 meters) per pixel.

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

Impact Craters on Rhea

N00203890.jpg was taken on March 09, 2013 and received on Earth March 10, 2013. The camera was pointing toward RHEA at approximately 2,348 miles (3,778 kilometers) away, and the image was taken using the CL1 and CL2 filters. This image has not been validated or calibrated. A validated/calibrated image will be archived with the NASA Planetary Data System in 2014.

Photo credit: NASA/JPL/Space Science Institute

Note: For more information, see Cassini Returns Images of Battered Saturn Moon.

Rhea

N00203868.jpg was taken on March 09, 2013 and received on Earth March 10, 2013. The camera was pointing toward RHEA at approximately 39,072 miles (62,880 kilometers) away, and the image was taken using the CL1 and CL2 filters. This image has not been validated or calibrated. A validated/calibrated image will be archived with the NASA Planetary Data System in 2014.

Photo credit: NASA/JPL/Space Science Institute

Note: For more information, see Cassini Returns Images of Battered Saturn Moon.

Crescent Rhea

The Cassini spacecraft captures Saturn's moon Rhea at crescent phase, a view never visible from Earth. Near the terminator, a few of Rhea's many craters show up in sharp relief.

With a diameter of 949 miles (1,528 kilometers) Rhea is Saturn's second-largest moon.

This view looks toward the leading hemisphere of Rhea. North on Rhea is up and rotated 12 degrees to the right.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on November 6, 2012. The view was obtained at a distance of approximately 1.2 million miles (1.9 million kilometers) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 129 degrees. Scale in the original image was 7 miles (11 kilometers) per pixel. The image was magnified by a factor of 1.5 to enhance the visibility of surface features.

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

Sinlap and Soi Craters

This set of images from the radar instrument on NASA's Cassini spacecraft shows a relatively "fresh" crater called Sinlap (left) and an extremely degraded crater called Soi (right). Sinlap has a depth-to-diameter ratio close to what we see on Jupiter's moon Ganymede. Soi has a shallow depth compared to similar craters on Ganymede. These craters are both about 50 miles (80 kilometers) in diameter.

The Sinlap image was taken by Cassini's radar instrument on February 15, 2005. The Soi image is a mosaic of two images from May 21, 2009 and July 22, 2006.

Image credit: NASA/JPL-Caltech/ASI/GSFC

Note: For more information, see Titan Gets a Dune 'Makeover'.

Bright Ejecta on Dione

Ejected material appears bright around some of Dione's craters in the image taken during the Cassini spacecraft's flyby of the moon on March 28, 2012.

This view is centered on terrain at 25 degrees north latitude, 128 degrees west longitude on Dione (698 miles, 1123 kilometers across).

See PIA10464 to see ejecta, or material thrown outward by the impact that formed a crater, covering a large area on the moon Rhea.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 28,000 miles (45,000 kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 55 degrees. Image scale is 876 feet (267 meters) per pixel.

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

Tethys

The Cassini spacecraft takes a close look at a row of craters on Saturn's moon Tethys during the spacecraft's April 14, 2012, flyby of the moon.

Three large craters are visible along the terminator between day and night on Tethys (660 miles, or 1,062 kilometers across). The larger Odysseus crater also can be seen in profile on the right of the image. Odysseus Crater is 280 miles (450 kilometers) across. See PIA07693 for a closer view of Odysseus.

This view looks toward the area between the leading hemisphere and the anti-Saturn side of Tethys. North on Tethys is up and rotated 25 degrees to the right.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on April 14, 2012. The view was acquired at a distance of approximately 12,000 miles (20,000 kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 66 degrees. Image scale is a half mile (1 kilometer) per pixel.

Photo credit:

NASA/JPL-Caltech/Space Science Institute

Janus

Shadows darken parts of some of Janus' large craters as Cassini takes a close look during its flyby of this Saturnian moon on March 27, 2012.

See PIA10447 and PIA12714 for higher resolution views of Janus (111 miles, or 179 kilometers across). See PIA08170 and PIA08348 to learn about how Janus periodically swaps orbits with Epimetheus.

This view is centered on terrain at 13 degrees south latitude, 26 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 28,000 miles (45,000 kilometers) from Janus and at a Sun-Janus-spacecraft, or phase, angle of 109 degrees. Image scale is 892 feet (272 meters) per pixel.

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

Bright Material on Dione

N00186374.jpg was taken on May 2, 2012 and received on Earth May 3, 2012. The camera was pointing toward DIONE at approximately 15,183 kilometers away, and the image was taken using the CL1 and CL2 filters. This image has not been validated or calibrated. A validated/calibrated image will be archived with the NASA Planetary Data System in 2013.

Photo credit: NASA/JPL/Space Science Institute

The Face of Phoebe

Phoebe's true nature is revealed in startling clarity in this mosaic of two images taken during Cassini's flyby on June 11, 2004. The image shows evidence for the emerging view that Phoebe may be an ice-rich body coated with a thin layer of dark material. Small bright craters in the image are probably fairly young features. This phenomenon has been observed on other icy satellites, such as Ganymede at Jupiter. When impactors slammed into the surface of Phoebe, the collisions excavated fresh, bright material -- probably ice -- underlying the surface layer. Further evidence for this can be seen on some crater walls where the darker material appears to have slid downwards, exposing more light-colored material. Some areas of the image that are particularly bright - especially near lower right - are over-exposed.

An accurate determination of Phoebe's density -- a forthcoming result from the flyby -- will help Cassini mission scientists understand how much of the little moon is comprised of ices.

This spectacular view was obtained at a phase, or Sun-Phoebe-spacecraft, angle of 84 degrees, and from a distance of approximately 32,500 kilometers (20,200 miles). The image scale is approximately 190 meters (624 feet) per pixel. No enhancement was performed on this image.

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