CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Shadowing Saturn

Like a silvery pearl, an icy moon crosses the face of Saturn, while two of its siblings cast shadows onto the planet.

Rhea (1,528 kilometers, 949 miles across) hangs in the foreground. Near upper left on Saturn is the small shadow of Mimas. Near lower right is the penumbral shadow of Iapetus -- the part of the moon's shadow where Iapetus does not completely block the Sun.

This view looks toward the unilluminated side of the rings from less than a degree above the ringplane. The rings' shadows drape across the northern hemisphere.

Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were obtained with the Cassini spacecraft wide-angle camera on June 15, 2007 at a distance of approximately 1.2 million kilometers (744,000 miles) from Rhea and 1.7 million kilometers (1.1 million miles) from Saturn. Image scale is 71 kilometers (44 miles) per pixel on Rhea and 103 kilometers (64 miles) on Saturn.

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: April 2, 2009 (PIA 08392)
Image/Caption Information
  Shadowing Saturn
PIA 08392

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Alliance Member Comments
Red_dragon (Dec 1, 2007 at 5:00 AM):
Very nice image as usual. Until recently, when i rode the entire image caption, I believed the penumbral shadow of Iapetus was a a storm system. I guess I'll have to read captions entirely...
ANAKA HURAKAN (Nov 4, 2007 at 1:23 PM):
after several orbital data returns iapetus;s ridge is composed of volcanic cinder cones that may explain why one hemisphere we will know more once ce'calcali returns from the surface c'kiasta end comment
ugordan (Oct 23, 2007 at 5:36 AM):
If Iapetus doesn't eclipse the entire Sun as seen from Saturn, there is no umbral shadow, only a penumbral one.
bruno.thiery (Oct 18, 2007 at 1:32 PM):

I wonder if this part of the comment is correct:

"Near lower right is the penumbral shadow of Iapetus -- the part of the moon's shadow where Iapetus does not completely block the Sun."

Shouldn't the penumbral shadow be adjacent / around the shadow?
In addition, the illumination seems to come from the lower left of the image.
Maybe the shadow on the lower right is the blocking by Rhea of the sunlight reflected by the rings.