Lack of dust suggests Saturn’s rings older than expected

Nature : NASA’s Cassini spacecraft has provided the first measurement of the rate at which dust is falling into Saturn’s rings. During seven years of observations, researchers detected only 140 particles whose trajectories indicate they came from elsewhere in the solar system. That rate is 40 times lower than expected. Because of the current level of dustiness, the rings may be much older than previously estimated. It is possible that the rings formed 4 billion years ago, soon after the planet itself formed. The previously estimated rate of dust collection was so high because it wasn’t known that the amount of dust outside the asteroid belt, where Saturn is located, is much lower than the amount inside, where Earth is located. Based on Cassini‘s data, it appears that most of the detected dust particles came from the Kuiper belt , a collection of frozen bodies outside the orbit of Neptune that includes Pluto and at least two other dwarf planets.