Rhea, one of the icy moons of Saturn, passes into the giant planet's shadow in a sequence of images snapped August 19 by the Cassini spacecraft. The first image shows Rhea before the eclipse begins, with the line between day and night at top. Large impact craters and cracks scar the surface, which is made primarily of frozen water. The shadow then slowly covers all but Rhea's north polar region. The last two images used longer exposure times to bring out more details in the eclipsed region. Cassini was about 280,000 miles (450,000 km) from Rhea. [NASA/JPL/SSI]