Two moons that have profound impacts on the rings, Mimas and Prometheus, are seen here with the F ring. Mimas, the larger and much more distant of the moons, maintains the sharp outer edge of the B ring. Prometheus, although much smaller than Mimas, is half of a duo responsible for maintaining the narrow F ring.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Oct. 20, 2008 at a distance of approximately 1.052 million kilometers (654,000 miles) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 29 degrees. Image scale is 6 kilometers (4 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.