Saturn has 67 known moons orbiting the planet. 38 are officially named and 29 are waiting to be named. The largest moon is Titan, which is larger in volume than the planet Mercury. Titan is the second-largest moon in the Solar System. The largest moon is Jupiter's moon, Ganymede. There is also a very large system of rings around Saturn. These rings are made of ice with smaller amounts of rocks and dust. Some people believe that the rings were caused from a moon impact or other event. Saturn is about 1,433,000,000 km (869,000,000 mi) on average from the Sun. Saturn takes 29.6 Earth years to revolve around the Sun.