CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Punching through the F Ring

Punching through the F Ring
PIA 11662

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  This image, taken as Saturn approaches its August 2009 equinox, shows a shadow being cast by a narrow, vertically extended feature in the F ring.

Imaging scientists are working to understand the origin of structures such as this one, but they think this image may show the shadow of an object on an inclined orbit which has punched through the F ring and dragged material along in its path.

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 PIA11663) 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 unilluminated side of the rings from about 27 degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 11, 2009. The view was acquired at a distance of approximately 866,000 kilometers (538,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 30 degrees. Image scale is 5 kilometers (3 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 11662)
Image/Caption Information

Alliance Member Comments
stowaway (Aug 8, 2009 at 3:30 PM):
Amazing! I must have missed the earlier PIA11663 - "Shadows in the F ring" image. But it's not hard for me to imagine that these objects would have inclined orbits. Seems there are many possible scenarios to explain it.
Iapetus Monolith (Aug 8, 2009 at 6:18 AM):
An extraordinary and dramatic image - congratulations to the imaging team! It is indeed hard to think of an explanation other than that of an object in an inclined orbit punching through the ring system. Have objects in such strongly inclined orbits previously been identified? How are we to account for the inclination: are such objects of extraneous origin, captured by Saturn's gravitational field?