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Saturn's rings cast a narrow shadow on the planet in a 2009 image from Cassini. Image: NASA / JPL / Space Science Institute

Shadows from Saturn's rings can affect the planet's atmosphere, according to an analysis of data collected by the Cassini-Hyugens spacecraft during its final dives into the gaseous planet's upper atmosphere earlier this year. The work was presented yesterday at the American Geophysical Union conference and will be published this week in the journal Science.

Why it matters: These are the first direct measurements of Saturn's ionsophere as opposed to remote sensing observations, study author William Kurth from the University of Iowa tells Axios. Much of our knowledge of other planets is based on that about Earth, with modifications to account for what we know to be different. By sampling the ionosphere of Saturn, Kurth says researchers can begin to check these modified theories. "An important outcome, though, is that the improved theories incorporating things we learn at other planets, should help us understand our own planet better than we do."

Sound smart: The ionosphere is an upper layer of a planet's atmosphere that is electrically charged by the Sun's ultraviolet radiation. Saturn's extends from 300 km - 5,000 km above its surface. (Earth also has one. Ditto Jupiter. It is where auroras occur. )

How it works: Ultraviolet radiation from the sun can separate an electron from an atom of hydrogen or helium, charging the ionosphere. Parts of the ionosphere in the shadow of Saturn's A- and B-rings have a lower density of free electrons than other regions, suggesting the rings may be blocking the Sun's UV radiation.

Yes, but: The shadows account for some of the variations Cassini measured, but not all, the researchers said. One possibility is ice particles from the rings may interact with electrons in the ionosphere in certain places during a so-called "ring rain." Another is winds may be blowing the particles or the UV radiation from the Sun itself may vary.

What's next: The researchers analyzed data collected from just one of Cassini's probes and from the first 11 of its 22 dives so there is more to be studied.

"This [Cassini] data set will eventually provide a deep understanding of the ionosphere and its interaction with the rings. These analyses will continue not only this year, but for decades to come," says Kurth. "New questions will come from these studies and provide the basis for possible return missions to the Saturnian system."

Go deeper

Republicans pledge to set aside differences and work with Biden

President Biden speaks to Sen. Mitch McConnell after being sworn in at the West Front of the U.S. Capitol on Wednesday. Photo: Erin Schaff-Pool/Getty Images

Several Republicans praised President Biden's calls for unity during his inaugural address on Wednesday and pledged to work together for the benefit of the American people.

Why it matters: The Democrats only have a slim majority in the Senate and Biden will likely need to work with the GOP to pass his legislative agenda.

The Biden protection plan

Joe Biden announces his first run for the presidency in June 1987. Photo: Howard L. Sachs/CNP/Getty Images

The Joe Biden who became the 46th president on Wednesday isn't the same blabbermouth who failed in 1988 and 2008.

Why it matters: Biden now heeds guidance about staying on task with speeches and no longer worries a gaffe or two will cost him an election. His staff also limits the places where he speaks freely and off the cuff. This Biden protective bubble will only tighten in the months ahead, aides tell Axios.

Bush labels Clyburn the “savior” for Democrats

House Majority Whip James Clyburn takes a selfie Wednesday with former President George W. Bush. Photo: Patrick Semansky-Pool/Getty Images

Former President George W. Bush credited Rep. James Clyburn with being the "savior" of the Democratic Party, telling the South Carolinian at Wednesday's inauguration his endorsement allowed Joe Biden to win the party's presidential nomination.

Why it matters: The nation's last two-term Republican president also said Clyburn's nod allowed for the transfer of power, because he felt only Biden had the ability to unseat President Trump.