Saturday, March 31, 2012

Dione


This raw image from NASA's Cassini spacecraft was taken on March 28, 2012. The camera was pointing toward Saturn's moon Dione at approximately 49,087 miles (78,998 kilometers) away.

Photo credit:
NASA/JPL/Space Science Institute

Note: For more information, see: Enceladus Plumes and Dione.

Friday, March 30, 2012

Enceladus Plumes


The international Cassini spacecraft was on its way to its lowest pass yet over the south polar region of Saturn's moon Enceladus when it took this image of the impressive plumes.

The plumes are jets of water ice and vapor, mixed with organic compounds. With this flyby coming within a mere 74 km, scientists hope to learn more about the composition, density and variability of these remarkable features of Enceladus.

Photo credit: NASA/JPL/Space Science Institute

Note: For more information, see: a) Enceladus Plumes and Dione, b) Icy Moons Through Cassini's Eyes, and c) Is it Snowing Microbes on Enceladus?

Tuesday, March 27, 2012

Quieted Storm


The Cassini spacecraft examines Saturn and the planet's northern hemisphere, which was ravaged by a huge storm for much of 2011.

See PIA14905 and PIA14903 to learn more about the storm.

Four of Saturn's moons join the planet here. Two of these -- Janus and Epimetheus -- are almost lost in this view due to their small size. Mimas (246 miles, or 396 kilometers across) appears as a bright dot below the rings just to the right of the center of the image. Enceladus (313 miles, or 504 kilometers across) is visible below the rings on the far right of the image. Janus (111 miles, or 179 kilometers across) can just barely be discerned as a tiny speck past Enceladus on the right edge of the image. Epimetheus (70 miles, or 113 kilometers across) is likewise tiny, and can be detected on the extreme left of the image above the rings.

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

Relative to Saturn and other objects in this view, Janus and Epimetheus have been brightened by a factor 1.5 and 1.4 respectively.

The image was taken with the Cassini spacecraft wide-angle camera on February 11, 2012 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was acquired at a distance of approximately 1.7 million miles (2.8 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 60 degrees. Image scale on Saturn is 105 miles (170 kilometers) per pixel.

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

Monday, March 26, 2012

Stress at Enceladus


These images, based on ones obtained by NASA's Cassini spacecraft, show how the pull of Saturn's gravity can deform the surface of Saturn's moon Enceladus in the south polar region crisscrossed by fissures known as "tiger stripes." The blue arrows show the different kinds of stress that can occur at the tiger stripes, allowing jets of water vapor and organic particles to spray out. As Enceladus orbits Saturn, Saturn's gravitational forces can cause the fissure to pull apart (middle panel) or cause the two banks to move side-to-side like California's San Andreas Fault. The red stripe shows where gaps open because of motion and would be places where material could erupt. The images here focus on the tiger stripe known as Alexandria Sulcus.

Image credit: NASA/JPL-Caltech/SSI/LPI/GSFC

Note: For more information, see Cassini Sees Saturn Stressing out Enceladus.

Wednesday, March 21, 2012

Hyperion from a Distance


The Cassini spacecraft gazes at Saturn's far-off moon Hyperion.

This view was obtained at a distance of approximately 324,000 miles (521,000 kilometers) from Hyperion and at a Sun-Hyperion-spacecraft, or phase, angle of 90 degrees. 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.) See PIA06243 and PIA07761 to learn more and to watch a movie.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on January 25, 2012. Scale in the original image was 2 miles (3 kilometers) 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

Thursday, March 15, 2012

Rhea


NASA's Cassini spacecraft took this raw, unprocessed image of Saturn's moon Rhea on March 10, 2012. The camera was pointing toward Rhea at approximately 26,019 miles (41,873 kilometers) away.

Photo credit: NASA/JPL-Caltech/SSI

Note: For other images in this series, see Rhea's Surface, Rhea Close-up, and Shadowed Rhea.

Wednesday, March 14, 2012

Enceladus


Below a darkened Enceladus, a plume of water ice is backlit in this view of one of Saturn's most dramatic moons.

See PIA11688 and PIA08386 to learn more about the jets of water ice emanating from the south polar region of Enceladus. Lit terrain seen here is on the leading hemisphere of Enceladus (313 miles, or 504 kilometers across). North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on February 20, 2012. The view was acquired at a distance of approximately 83,000 miles (134,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 165 degrees. Image scale is 2,628 feet (801 meters) per pixel.

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

Tuesday, March 6, 2012

Prometheus and the Rings


The Cassini spacecraft looks across Saturn's rings and finds the moon Prometheus, a shepherd of the thin F ring.

Prometheus (53 miles, or 86 kilometers across) looks like a small white bulge near the F ring -- the outermost ring seen here -- above the center of the image. See PIA08397 and PIA07712 to learn how the moon perturbs the F ring.

Kinky, discontinuous ringlets can also be seen in the Encke Gap of the A ring on the left of the image. See PIA12650 to learn more.

This view looks toward the southern, unilluminated side of the rings from about 1 degree below the ringplane. Four background stars are visible.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on January 1, 2012. The view was acquired at a distance of approximately 1.1 million miles (1.8 million kilometers) from Prometheus. Image scale is 7 miles (11 kilometers) per pixel.

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

Sunday, March 4, 2012

Dione in False Colors


This view highlights tectonic faults and craters on Dione, an icy world that has undoubtedly experienced geologic activity since its formation.

To create the enhanced-color view, ultraviolet, green and infrared images were combined into a single black and white picture that isolates and maps regional color differences. This "color map" was then superposed over a clear-filter image. The origin of the color differences is not yet understood, but may be caused by subtle differences in the surface composition or the sizes of grains making up the icy soil.

This view looks toward the leading hemisphere on Dione (1,126 kilometers, or 700 miles across). North is up and rotated 20 degrees to the right.

See PIA07690 for a similar monochrome view.

All images were acquired with the Cassini spacecraft narrow-angle camera on December 24, 2005 at a distance of approximately 151,000 kilometers (94,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 99 degrees. Image scale is 896 meters (2,940 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Note: For more information, see Cassini Detects Hint of Fresh Air at Dione.