CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Tethys in the Dark

A close inspection of this image reveals that there is more of Tethys (1,062 kilometers, 660 miles across) here than is apparent at first glance. A slim crescent is all that is visible of the moon's sunlit side, but the left half of the image is dimly lit by "Saturnshine", or reflected light from the planet lying off to the left of Cassini's field of view.

On occasion, useful details about a moon's surface characteristics can be revealed under such dim illumination, as in PIA06168.

This view shows principally the Saturn-facing hemisphere of Tethys; north is up. Craters along terminator are Penelope (top) and Antinous (bottom).

The image was taken with the narrow angle camera on Aug. 3, 2005 from a distance of approximately 842,000 kilometers (523,000 miles) through a filter sensitive to wavelengths of polarized ultraviolet light centered at 338 nanometers from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 144 degrees. Image scale is 5 kilometers (3 miles) per pixel.

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: September 1, 2005 (PIA 07577)
Image/Caption Information
  Tethys in the Dark
PIA 07577

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