CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Pan's Effects

Saturn's moon Pan, orbiting in the Encke Gap near the top of the image, casts a short shadow on the A ring in this image taken about six months after the planet's August 2009 equinox.

Pan (28 kilometers, 17 miles across) also creates dark wakes, which can faintly be seen here immediately interior to the inner edge of the Encke Gap. See PIA07537 for another example.

The shadow of the planet is cast diagonally across the rings at the top of the image. Five background stars are visible.

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 southern, unilluminated side of the rings from about 17 degrees below the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 8, 2010. The view was acquired at a distance of approximately 1.7 million kilometers (1.1 million miles) from Saturn. Image scale is 10 kilometers (6 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: March 31, 2010 (PIA 12601)
Image/Caption Information
  Pan's Effects
PIA 12601

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Alliance Member Comments
raketenflugplatz (Oct 21, 2011 at 12:08 PM):
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stowaway (Mar 31, 2010 at 12:29 PM):
very nice