CICLOPS: Cassini Imaging Central Laboratory for OPerationS

Pan's Shadow
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Pan's Shadow
PIA 12640

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  Saturn's small moon Pan casts a long shadow across the A ring in this image captured by Cassini a few days after the planet's August 2009 equinox.

Pan (28 kilometers, 17 miles across) can be seen orbiting in the Encke Gap of the A ring below the center of the image. The thin F ring is at the very bottom of the image. The shadow is interrupted by the crest of a bending wave on the right of the image. See PIA10501 to learn more about such waves.

The novel illumination geometry that accompanies equinox lowers the sun's angle to the ringplane, significantly darkens the rings, and causes out-of-plane structures to look anomalously bright and cast shadows across the rings. These scenes are possible only during the few months before and after Saturn's equinox which occurs only once in about 15 Earth years. Before and after equinox, Cassini's cameras have spotted not only the predictable shadows of some of Saturn's moons (see PIA11657), but also the shadows of newly revealed vertical structures in the rings themselves (see PIA11665).

This view looks toward the northern, sunlit side of the rings from about 18 degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 14, 2009. The view was obtained at a distance of approximately 1.4 million kilometers (870,000 miles) from Pan. Image scale is 9 kilometers (5 miles) per pixel.

The Cassini Equinox Mission is a joint United States and European endeavor. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. 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 Equinox Mission visit, and

Credit: NASA/JPL/Space Science Institute
Released: May 25, 2010 (PIA 12640)
Image/Caption Information

Alliance Member Comments
Dragon_of_Luck_Mah_Jonng1971 (May 28, 2010 at 5:56 AM):
Interesting shadow of Pan.