Saturn's moon Epimetheus passes in front of Janus in this "mutual event" chronicled by the Cassini spacecraft.
These three images were each taken a little more than a minute apart. These images are part of a mutual event sequence in which one moon passes close to or in front of another. Such observations help scientists refine their understanding of the orbits of Saturn's moons. See Catching Big Sister to watch a movie of a mutual event.
This view looks toward trailing hemispheres of Janus (179 kilometers, or 111 miles across) and Epimetheus (113 kilometers, or 70 miles across). Janus is approximately 748,000 kilometers (465,000 miles) from Cassini. Epimetheus is approximately 733,000 kilometers (455,000 miles) away.
The moons are brightly lit on the left by sunlight. Sunlight reflected by Saturn is dimly lighting both moons on the right of the images.
The images were taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 14, 2010. Scale in the original images was approximately 4 kilometers (2 miles) per pixel on Janus and on Epimetheus. The images were contrast enhanced and magnified by a factor of two to enhance the visibility of surface features.
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.
Credit: NASA/JPL/Space Science Institute