Science: Saturn's rings are disappearing

2023-05-25 17:03:23

Saturn’s iconic icy rings may no longer be there for future skywatchers, according to new research.

NASA’s Cassini space probe, launched in 1997 and placed in orbit of the giant gas planet from 2004 to 2017, has captured a lot of new data, making it possible to estimate the lifespan of the rings, as well as the time at which they can disappear.

Young rings…

While our solar system and the planets that make it up date to around 4.6 billion years ago, data from Cassini has led to a new discovery. According to the results of studies published on May 12 and 15 in the journals Icarus and Science Advances, the theory of rings appearing long after the initial formation of Saturn is advanced.

“Our inescapable conclusion is that Saturn’s rings must be relatively young by astronomical standards, only a few hundred million years old,” said Richard Durisen, professor of astronomy at Indiana University (States States) and lead author of the two studies published in Icarus.

According to the researchers, it is likely that the seven rings were still forming when dinosaurs roamed the Earth.

Made up of 95% ice particles, they reflect sunlight and appear white. But white is messy. Dust, made up of grains made up of rocks, metals or carbon-rich materials, gradually darkens the rings by settling on them.

Knowing the flux of dust around Saturn, and estimating the quantity deposited on the rings, the researchers were thus able to give a range of the age of the rings.

In 13 years, the cosmic dust analyzer was able to pick up 163 grains of dust from beyond the Saturn system. The rings were surprisingly “clean”, suggesting that they must not have been there long enough to accumulate excess cosmic dust.

Who won’t live to be old

Indeed, the rings are polluted by small meteorites which collide with the ice particles, precipitating their fall towards the planet. Cassini observed that the rings would thus lose several tons of matter every second. Researchers estimate that the rings will only last a few hundred million years at most.

Paul Estrada, a researcher at NASA’s Ames Research Center and co-author of the three studies, concludes: “We have shown that massive rings like Saturn’s don’t last long. It can be assumed that the relatively puny rings around the other ice and gas giants of our solar system (Uranus and Neptune) are remnants of rings that were once massive like those of Saturn. Perhaps in the not-too-distant future, astronomically speaking, Saturn’s rings will look more like the sparse ones of Uranus.”