CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Not Quite Round

Not Quite Round
PIA 07534

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  Mimas (396 kilometers, 246 miles across), whose low density suggests that it is primarily composed of ice, has a flattened, or oblate, shape reminiscent of Saturn's (see PIA05389). The moon's equatorial dimension is nearly 10 percent larger than the polar one due to the satellite's rapid rotation.

This view shows principally the leading hemisphere on Mimas. Mimas' largest crater, Herschel (130 kilometers, 80 miles wide), is centered roughly on the equator and can be seen here. North on Mimas is toward upper left.

The moon's oblateness is exaggerated by Cassini's viewing angle here - the Sun-Mimas-spacecraft, or phase, angle was 5 degrees leaving a sliver of the moon's disk in shadow on the northwest limb.

The image was taken in visible light with the narrow angle camera on May 20, 2005, from a distance of approximately 916,000 kilometers (569,000 miles) from Mimas. Resolution in the original image was 5 kilometers (3 miles) per pixel. The image has been contrast-enhanced and magnified by a factor of two to aid visibility.

The Cassini-Huygens mission is a cooperative project of NASA, 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 Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission, visit and the Cassini imaging team home page,

Credit: NASA/JPL/Space Science Institute
Released: July 4, 2005 (PIA 07534)
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