Moon Shadows on Planet Saturn | Hubble Space Telescope FriendsofNASA.org: Saturn's wide, but very thin, rings are tilted with respect to its plane of orbit around the Sun. Once every 15 years, the rings are edge-on (perpendicular) to the Sun. During those times, Saturn's moons can cast shadows across the rings. This time-lapse video shows the icy moons Enceladus, Mimas, Dione, and Tethys orbiting Saturn. Enceladus, seemingly chased by Mimas, is first to speed past the rings and in front of the p