Telesto

Caption NASA originale:"Saturn's moon Telesto is visible below and to the left of center in this image from the Cassini spacecraft.
Telesto (only 24 Km across) shares the orbit of Saturn's moon Tethys (1.071 Km across), leading the larger moon in its path by 60°. Similarly sized Calypso (22 Km across) trails Tethys by the same amount. These positions, called Lagrange points, are dynamically stable. In being co-orbital moons of Tethys, Telesto and Calypso are like the Trojan moons of Jupiter, which occupy Lagrange points and orbit 60° ahead and behind of Jupiter. The Saturnian moon Dione also has companion moons: Helene, which leads Dione in its orbit and the Cassini-discovered trailing Lagrange moon, Polydeuces. This image was taken in visible light with the Cassini spacecraft narrow angle camera on Jan. 18, 2005, at a distance of approximately 3,7 MKM from Telesto. Resolution in the image is 7 Km per pixel. Telesto has been brightened by a factor of two to aid visibility".