Thursday, December 29, 2011

Titan and Saturn


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

Wednesday, December 28, 2011

Titan and Dione


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

Tuesday, December 27, 2011

Enceladus


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

Monday, December 26, 2011

Titan and Tethys


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

Sunday, December 25, 2011

Titan and Dione in Natural Colors


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

Saturday, December 24, 2011

Titan


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

Thursday, December 22, 2011

Dione


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

Wednesday, December 21, 2011

Enceladus and Epimetheus by Saturn's Terminator


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

Tuesday, December 20, 2011

Dione


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.

Tuesday, December 13, 2011

Dione


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

Wednesday, December 7, 2011

Mimas, Prometheus and the Rings


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

Saturday, December 3, 2011

Southern Enceladus in Radar View


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.