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Cassini spies icy moons of Saturn

David Dickinson, Correspondent
Jul 8, 2015, 0:47 UTC

Sen—NASA’s Cassini spacecraft has been delivering more amazing pictures of Saturn and its satellites recently, including one of Saturn's smallest moons, Prometheus.

The main image, above, also shown in full below, was taken on March 15, 2015, and shows the potato-shaped tiny moon Prometheus sculpting the tenuous outer F-ring of Saturn. The dark spiral lanes are evidence of the moon’s handiwork, as it braids and slices the rings on each successive pass like a blunt razor.

The image was taken from a distance of 461,000 km (286,000 miles, a little over the distance from the Earth to the Moon) and was taken by Cassini looking back from seven degrees below the plane of the rings towards the night side of the planet.


Prometheus (upper right) captured by Cassini against Saturn's F-ring. Image credit: NASA/JPL-Caltech/Space Science Institute

The image is not a mosiac but a single capture of a fortuitous alignment from the spacecraft’s narrow-angle camera.

Prometheus is about 135 km (80 miles) across on its long axis, and was discovered during the 1980 Voyager 1 flyby of Saturn. Saturn currently has 62 known moons.

The dim F-ring is not visible in a backyard telescope, and was first spotted by the Pioneer 11 spacecraft in 1979. The tiny shepherd moons of Pandora and Prometheus tend to the F Ring.

Cassini also recently captured this triple crescent on March 25, 2015, of Titan, Mimas and Rhea:


Saturn's largest moon Titan (center right), Rhea (upper left) and Mimas (center bottom) imaged by Cassini's narrow angle camera on March 25, 2015. Image credit: NASA/JPL-Caltech/Space Science Institute

Cassini entered orbit around Saturn in 2004, and continues to explore the realm of the ringed planet. Now well into its extended mission over a decade later, Cassini will end its career with a fiery plunge into the atmosphere of Saturn in 2017.