Could The Shadow Of Saturn’s Rings Affect Its Weather?

Thanks to the Cassini-Huygens spacecraft, which plunged into Saturn’s atmosphere earlier this year, scientists have been able to collect more and more data on the planet. Now they report that the data they’ve analyzed so far suggests that the shadow of Saturn’s rings affect its weather.

Saturn's rings
Credit: NASA/JPL-Caltech/Space Science Institute

Scientists from Sweden and the United States conducted a new research study which shows the difference between the particles in the northern and southern parts of the planet’s ionosphere, which is Saturn’s electrically-charged layer. After immersing itself in the planet’s atmosphere three months ago, the Cassini probe continues to deliver new data about the planet.

“One can imagine this as the grand finale phase of the Cassini mission as an entirely new mission with the veteran spacecraft,” William Kurth, a scientist at the University of Iowa’s Department of Physics and Astronomy, revealed to Gizmodo. “There was never any plan to go this close to Saturn… we’re just getting our feet wet with the fresh data that we have.”

The scientists recognize Saturn as a gas giant because it doesn’t have a solid surface. Thus, they define the planet’s surface as the place where the pressure is one bar, which is a little less than the average pressure at sea level, 37,550 miles from its center. The ionosphere starts at around 186 miles up and goes out to 3,100 miles up. To put this into perspective, Earth’s ionosphere goes from 37 miles to 620 miles up and has a radius of about 3,980 miles. The ionosphere consists of particles that are ionized, becoming positively charged as a result of losing electrons due to the sun’s radiation.

Cassini entered Saturn’s ionosphere on April 27 and started orbiting the planet. During that time, scientists managed to collect data using the probe’s Radio and Plasma Wave Science (RPWS) instruments. Cassini measured the density of electrons and ionized particles, but it also found that the A and B rings’ shadow affect the planet’s weather in the southern part of the ionosphere.

Those results can help scientists explain the way particles move around the planet, which can be important in explaining other gas planets. There’s a lot more data that the scientists need to analyze in order to understand the planet’s atmosphere. Kurth told Gizmodo that these results on Saturn’s rings are from only one of the spacecraft’s instruments and the first 11 of many orbits. Also the results don’t use data from the time the probe plunged into the atmosphere.

“It’s just terrific,” he said. “It’s sad that the spacecraft is no longer with us, but it’s left such a legacy in terms of observation not just for the last six months but the entire 13 years.”

The findings about how the shadow of some of Saturn’s rings affect the planet’s weather have been published in the journal Science. The scientists also talked about them at the American Geophysical Union’s Fall meeting in New Orleans.