NASA recently published a wonderful view of five Saturnian moons, acquired by the Saturn-orbiting Cassini spacecraft. Rhea (1,528 km across), Saturn’s second largest moon, dominates the picture, while Saturn’s magnificent rings are visible nearly edge-on, below Rhea. (The names of most planetary moons come from mythologies.)
Rhea was closest to Cassini, at the time the image was taken. Dione (1,123 km across) appears just above the rings, near the center of the image. Tiny Prometheus (86 km across) is just barely visible as a small clump in the rings, to the right of Dione. Epimetheus (113 km across), another small moon, can be seen as a small speck of light, to the right of the rings, while Tethys (1,062 km across) is on far right of the image.
The image was taken in visible light with the Cassini spacecraft wide-angle camera, on 11 January 2011. Cassini was at a distance of approximately 61,000 km from Rhea. Cassini was looking on the sunlit side of the rings, from just above the plane of the ring.
Saturn has a large family of satellites, including 62 moons and numerous smaller objects, known as moonlets. Saturn’s moons range widely in size, from Titan (5,150 km across), to tiny, irregularly-shaped moons, measuring a few kilometers wide. Seven of Saturn’s moons are large, but are all, except for Titan, smaller than Earth’s Moon (3,476 km across).
References
NASA’s Cassini Website
http://www.nasa.gov/mission_pages/cassini/main/index.html
Wikipedia