The giant orange moon Titan — larger than the planet Mercury — can be seen at upper right. The white icy moons that are much closer to Saturn, hence much closer to the ring plane in this view, are, from left to right: Enceladus, Dione, and Mimas. The dark band running across the face of the planet slightly above the rings is the shadow of the rings cast on the planet
Mimas (near lower left) appears tiny by comparison, so it might seem that Saturn's rings would be far more massive, but scientists think the rings are no more than a few times as massive as Mimas, or perhaps just a fraction of its mass. Cassini is expected to determine the mass of Saturn's rings to within just a few hundredths of Mimas' mass by tracking radio signals from the from the spacecraft as it flies close to the rings. Mimas is 246 miles (396 kilometers) wide.
Photogenic #Saturn has now become a movie star. Astronomers have woven NASA Hubble Space Telescope images of Saturn, its rings, and several of its moons into three movies. Each movie highlights unique times in the planet's 30-year waltz around the Sun. Two of the movies show the motion of several of Saturn's moons when the planet's rings were tilted nearly edge-on to Earth and to the Sun. These edge-on alignments of the rings occur roughly once every 15 years.