New Crater on Titan

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

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

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

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

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

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

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

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

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

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