Saturn’s Disappearing Rings – New Insights

Researchers have found that Saturn’s rings lose their luster and darken over time. It also seems to be shrinking.

In addition to Saturn, the planets Jupiter, Uranus and Neptune also have rings in our solar system. Recent studies suggest that Saturn’s rings are the brightest, as they make up nearly 95 percent of the water ice—although their brightness doesn’t last forever.

Three recently published studies analyzed data from NASA’s Cassini spacecraft, which orbited Saturn from 2004 to 2017 and collected information about the planet’s moons, atmosphere and rings. Investigations provide new evidence of the rings’ age, as well as their demise.

Due to their large surface area, the rings are very susceptible to bombardment by micrometeorites from the Saturnian system. Since the initially bright rings consist mostly of chunks of ice and a small percentage of small rock particles, the buildup of cosmic dust will cause them to darken over time. This can help determine the age of the pieces of ice.

“Think of rings like a carpet in your home,” said Sasha Kempf, a University of Colorado Boulder physicist who led one of the studies published in the journal Science Advances. “Once you have a clean carpet, all you have to do is wait. The dust will settle on your carpet.” The same applies to rings.

The age of Saturn’s rings has been a matter of debate among scientists for years. More recently, researchers hypothesized that they only existed about 160 million years ago.

By analyzing 163 grains of dust from outside the Saturnian system that Cassini collected from its rings, scientists have estimated in the latest analysis that the rings are no more than 400 million years old – and may have formed before the arrival of the dinosaurs on Earth. Compared to the 4.5 billion years Saturn has existed, its rings are relatively young.

One study, published in the scientific journal Icarus, suspects that the rings could also be short-lived, only existing for another 15 to 400 million years. The reason, according to the researchers, is that meteorites bombarding the icy rings cause some of their material to drift inward toward Saturn. As a result, the rings are steadily losing mass.

The current findings indicate that Saturn’s rings may eventually resemble the thinner and darker rings of Uranus and Neptune in the future, Paul Estrada, a researcher at NASA Ames Research Center and co-author of all three studies, said in a statement.