Rhea and Enceladus shared the sky just before the smaller moon passed
behind its larger, cratered sibling.
This image is part of a "mutual event" series in which one moon passes
close to or in front of another. These sequences help scientists refine
the orbits of Saturn's moons.
Cratered Rhea is 1,528 kilometers (949 miles) across and presumed to be
geologically dead. While much smaller, Enceladus (505 kilometers, or 314
miles across) is geologically active today.
The image was taken in visible light with the Cassini spacecraft
narrow-angle camera on July 4, 2006 at a distance of approximately 1.4
million kilometers (800,000 miles) from Rhea and 1.9 million kilometers
(1.2 million miles) from Enceladus. The view was obtained at a
Sun-moon-spacecraft, or phase, angle of about 142 degrees relative to
both moons. Image scale is 8 kilometers (5 miles) per pixel on Rhea and
11 kilometers (7 miles) on Enceladus.
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/home/index.cfm. The Cassini imaging team
homepage is at http://ciclops.org.
