CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Shadows in the F ring

Cassini spies a shadow being cast by a vertically extended structure or object in the F ring in this image taken as Saturn approaches its August 2009 equinox.

The structure can be seen as a bulge near the bright core of the ring on the right of the image. Imaging scientists are working to understand the origin of structures such as this one, but they think this image shows the shadow of what appears to be a vertically extended object in the core of the F ring.

The second (bottom) version of the image has been brightened to enhance the visibility of the ring and shadow. Background stars appear elongated in the image because of the camera's exposure time.

This image and others like it (see PIA11662) are only possible around the time of Saturn's equinox which occurs every half-Saturn-year (equivalent to about 15 Earth years). The illumination geometry that accompanies equinox lowers the sun's angle to the ringplane and causes out-of-plane structures to cast long shadows across the rings. 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 PIA11654).

This view looks toward the sunlit side of the rings from about 54 degrees below the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 9, 2009. The view was obtained at a distance of approximately 592,000 kilometers (368,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 97 degrees. Image scale is 3 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: August 7, 2009 (PIA 11663)
Image/Caption Information
  Shadows in the F ring
PIA 11663

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Alliance Member Comments
stowaway (Aug 8, 2009 at 3:37 PM):
ok - So here's the image I thought I had missed. Seems likely this could be a transitory clump of material rather than a solid object, perhaps created by a earlier swing-by of Prometheus.