Monday, February 15, 2016

Cassini Sees Dione Cut in Two

Credit: NASA/JPL/Space Science Institute

Dione appears cut in two by Saturn's razor-thin rings, seen nearly edge-on in a view from NASA's Cassini spacecraft. This scene was captured from just 0.02 degrees above the ringplane. The bright streaks of Dione's wispy terrain (see Wispy Marble) are seen near the moon's limb at right. The medium-sized crater Turnus (63 miles, 101 kilometers, wide) is visible along Dione's terminator.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 25, 2015. The view was acquired at a distance of approximately 1.4 million miles (2.3 million kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 115 degrees. Image scale is 8.6 miles (13.8 kilometers) per pixel.

At 1,122 kilometers (697 miles) in diameter, Dione is the 15th largest moon in the Solar System, and is more massive than all known moons smaller than itself combined. About two thirds of Dione's mass is water ice, and the remaining is a dense core, probably silicate rock.

Dione's icy surface includes heavily cratered terrain, moderately cratered plains, lightly cratered plains, and areas of tectonic fractures. The heavily cratered terrain has numerous craters greater than 100 kilometers (62 miles) in diameter.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

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