CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Shadow Cap

Shadow Cap
PIA 10469

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  The shadow of Saturn's rings sits upon the northern hemisphere of Mimas like a dark cap. In this Cassini view, which looks toward high northern latitudes on Mimas, the moon is just grazing the shadow of the rings.

Another view, PIA10467, was acquired a few minutes prior to this image, and shows a nearly identical Mimas (396 kilometers, 246 miles across) before the rings' shadow obscured the surface.

The two distinct shadow regions seen here are the penumbra and the much darker umbra. An observer within the penumbral region on Mimas would have their view the Sun partly blocked by the rings. For a viewer within the umbral region, the rings would completely cover the Sun. However, since the rings are not opaque, the Sun would still be dimly visible.

The image was brightened to reveal faint details within the eclipsed region, illuminated dimly by sunlight filtering through the rings.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 4, 2008. The view was acquired at a distance of approximately 143,000 kilometers (89,000 miles) from Mimas and from about 67 degrees above the moon's equator. The Sun-Mimas-spacecraft, or phase, angle in the image is 106 degrees. Image scale is 856 meters (2,808 feet) 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: September 15, 2008 (PIA 10469)
Image/Caption Information

Alliance Member Comments
NeKto (Sep 16, 2008 at 9:39 AM):
Red-dragon, i like your sence of asthetics. you have brought my attention to some breathtaking images i might have missed. thanks.
Red_dragon (Sep 16, 2008 at 3:27 AM):
Least to say, striking; it looks as if Mimas was disguising of Iapetus.