Studies: Saturn’s Rings Relatively Young, And Dissolving

About 400 million years ago, North America, Greenland, and Europe were united in a single land mass, forests began covering the Earth, sharks started roaming the seas, and the first four-legged amphibians began the colonization of land by vertebrates.

Also, Saturn had no rings.

Scientists at NASA’s Ames Research Center in California’s Silicon Valley examined data from NASA’s Cassini mission from 2004 to 2017 that provided evidence that Saturn’s rings are young and temporary – in astronomical terms. They pegged the age of Saturn’s rings at between 100 million and 400 million years.

There has been a lot of debate among scientists about the age of the rings, which are made almost entirely of ice. Less than a few percent of the rings’ mass is made up of micrometeoroids, such as asteroid fragments smaller than a grain of sand. These constantly collide with the ring particles and contribute debris to the material circling the planet.

The study published in the May 12 edition of Science Advances indicates the micrometeoroids aren’t coming in as fast as scientists thought, which means Saturn’s gravity can pull the material more effectively into the rings. That means the rings could not have been exposed to such a cosmic hailstorm for more than a few hundred million years – a small fraction of Saturn’s age (4.5 billion years).

“The idea that the iconic main rings of Saturn might be a recent feature of our solar system has been controversial,” Jeff Cuzzi, a researcher at Ames and co-author of the study along with five other scientists, told NASA, “but our new results complete a trifecta of Cassini measurements that make this finding hard to avoid.”

Cuzzi served as the interdisciplinary scientist for Saturn’s rings during the Cassini mission.

Although humans were not around to see Saturn before its rings formed, it is possible that humans could one day see the planet without them. The Cassini mission discovered the rings are losing mass quickly because material from the innermost regions falls into the planet. Another study, published in the May 11 edition of Icarus, details how fast ring material is drifting in this direction and how micrometeoroids are playing a role.

Their collisions with existing ring particles and the way the resulting debris gets hurled outward combine to create a sort of conveyor belt of motion carrying ring material in toward Saturn. Through their calculations, scientists estimated Saturn might lose its rings in the next few hundred million years.

“I think these results are telling us that constant bombardment by all this foreign debris not only pollutes planetary rings, it should also whittle them down over time,” Paul Estrada, a researcher at Ames and co-author of both studies, told NASA. “Maybe Uranus’ and Neptune’s diminutive and dark rings are the result of that process. Saturn’s rings being comparatively hefty and icy, then, is an indication of their youth.”