Saturn's rings are familiar to schoolchildren and adults alike, but recent analysis of data from the final days of the Cassini spacecraft shows that the rings are -- geologically speaking -- relatively new.
A team from the Sapienza University of Rome took data from 22 orbits of the Cassini spacecraft between Saturn and its rings, then performed a complex analysis of the gravitational pull from both the planet and the icy particles that form the rings.
What they found and published in the journal Science was that the rings have a mass of about 15 million trillion kilograms, which sounds like a lot until you realize that it's only about 40% of the mass of Saturn's moon Mimas or a trillionth of Earth's mass. Based on the mass calculation and how much micrometeorite soot is falling onto the rings, the team believes the rings are anywhere from 10 to 100 million years old, with the data suggesting that the the higher number is more likely.
How the rings were formed is still a mystery. While some planetary scientists believe the rings were formed from a collision of several former moons, that theory doesn't explain why the debris would have formed rings rather than clumping into new moons. The team thinks that Saturn may have gravitationally "caught" a comet or icy asteroid, which was then torn apart by gravitational forces and eventually formed the rings.
The rings are "only" expected to last another couple hundred million years.