CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Shadows Side by Side

Shadows Side by Side
PIA 11618

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  A pair of moon shadows and a series of spokes adorn this ring image taken about a month after Saturn's August 2009 equinox.

The shadow of the moon Janus stretches across the middle of the image. The shadow of the moon Mimas runs across the bottom. Very faint, bright spokes are barely detectable just above Janus' shadow near the center of the image. To learn more about spokes, see PIA11144.

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 sunlit, northern side of the rings from about 8 degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 8, 2009. The view was acquired at a distance of approximately 3 million kilometers (1.9 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 104 degrees. Image scale is 17 kilometers (11 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: November 6, 2009 (PIA 11618)
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