Moons that Pass in the Night

Two of Saturn's ring moons draw close momentarily, before the inner of the pair moves off alone.

Atlas (30 kilometers, or 19 miles across, at center right) passes Prometheus (86 kilometers, or 53 miles across, at center left) about once a month, then slowly and steadily pulls ahead of its slower moving sibling.

This view looks toward the unilluminated side of the rings from about 23 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 6, 2008. The view was acquired at a distance of approximately 1.6 million kilometers (975,000 miles) from Atlas. Image scale is 9 kilometers (6 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.