CICLOPS: Cassini Imaging Central Laboratory for OPerationS

Shadow on Bright B Ring
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Shadow on Bright B Ring
PIA 11544

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  The shadow of the moon Epimetheus stretches across the B ring in this image taken by Cassini as Saturn approaches its 2009 equinox.

The novel illumination geometry created as Saturn approaches its August 2009 equinox allows moons orbiting in or near the plane of Saturn's equatorial rings to cast shadows onto 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. To learn more about this special time and to see movies of moons' shadows moving across the rings, see PIA11651 and PIA11660.

This view looks toward the sunlit side of the rings from about 42 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 8, 2009. The view was obtained at a distance of approximately 700,000 kilometers (435,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 129 degrees. Image scale is 4 kilometers (2 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: July 27, 2009 (PIA 11544)
Image/Caption Information

Alliance Member Comments
thetonster (Jul 29, 2009 at 8:59 PM):
Carolyn, PIA11544, or Cas5689-13230-2 seems to show a brightening in the widest part of Epimetheusí shadow. I donít recall any through-holes in any pictures of that little ice ball, nor did they reveal it to be washer-shaped. Pray tell, how can a shadow behave this way? Is Epi the same angular size as the Sun just now, and therefore this becomes an interior diffraction spot? It is mighty intriguing.

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