Confining Moons

Saturn's shepherd moons gravitationally herd the F ring's particles into a narrow thread.

The structure seen in the inner edge of the F ring in this wide-angle view is similar to that seen in the narrow-angle view Pan in the Fast Lane. Here, Prometheus is inside the ring's inner edge.

Along with Prometheus (102 kilometers, or 63 miles across) and Pandora (84 kilometers, or 52 miles across), two background stars are visible in the image. One of the stars is seen in the middle of the F ring.

This view looks toward the unilluminated side of the rings from about 45 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Jan. 26, 2008. The view was obtained at a distance of approximately 749,000 kilometers (465,000 miles) from Saturn. Image scale is 45 kilometers (28 miles) per pixel.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute