A new study has delivered the strongest evidence yet that Saturn’s rings are remarkably young; at no more than 400 million years old, compared to the planet which is estimated to be 4.5 billion years old.
To put that into perspective, it means sharks, which first emerged on Earth 450 million years ago, are older than the rings.
The team was able to determine the age limit by studying the build-up of a thin layer of dust on the ice that makes up Saturn’s seven rings.
Tiny grains called micrometeoroids constantly sweep through our solar system.
“Think about the rings like the carpet in your house. If you have a clean carpet laid out, you just have to wait. Dust will settle on your carpet. The same is true for the rings,” says lead researcher Sascha Kempf, Associate Professor in the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder, US.
The researchers could estimate how long the rings have existed by understanding how rapidly this layer of dust builds and gradually darkens the initially bright icy rings over time.
From 2004 to 2017, the team used an instrument called the Cosmic Dust Analyzer aboard NASA’s Cassini spacecraft to scoop up and analyse 163 specks of dust flying around Saturn.
They estimate that the interplanetary grime on Saturn’s rings would have built up over about 100 to 400 million years.
This raises the question as to how they formed in the first place.
“We know approximately how old the rings are, but it doesn’t solve any of our other problems. We still don’t know how these rings formed in the first place,” says Kempf.
The research is published in Science Advances.