Rain on Saturn
Scientists discover that ice from the planet’s rings can turn into rain
If you were to travel to Saturn, you might want to take an umbrella! It’s raining on Saturn, and scientists say the planet’s famous rings are the cause.
Saturn’s rings are made up almost entirely of ice. Tiny charged particles of the ice erode, or wear away, and travel into Saturn’s upper atmosphere as “rain.” The planet’s magnetic field creates pathways that the charged particles follow. Those pathways determine where it rains.
In a study released last month, scientists found that the amount of this “ring rain” is much greater, and that the rain falls across larger areas of Saturn, than they had previously thought.
“We estimate that one Olympic-sized swimming pool of water is falling on Saturn per day,” says James O’Donoghue, an astronomer at the United Kingdom’s University of Leicester who worked on the study.
In 2011, the scientists used the Keck Observatory in Hawaii to view parts of Saturn in greater detail than ever before. Hydrogen ions in the planet’s atmosphere cause the planet to glow. The ring rain neutralizes those ions, causing them to stop glowing. That leaves “shadows” on the parts of the planet where the rain falls. The shadows cover 30 percent to 43 percent of Saturn’s upper atmosphere.
“Saturn is the first planet to show significant interaction between its atmosphere and ring system,” says O’Donoghue.
The magnetic field that governs where it rains on the planet could also control the spacing and composition of the rings. That could explain why Saturn’s rings are all different sizes and densities.
“It’s quite possible that the rings we see today were shaped—or sculpted—by this process,” says Jack Connerney, a scientist at NASA, the U.S. space agency. “And who knows—a few tens of millions of years from now [they] can look quite different.”
Now scientists are questioning how the ring rain affects the rings, and whether studying the rate of the rain might help them figure out the age of the rings. They also question whether the rain will eventually cause the rings to disappear.