Winds, swirling through two massive vortices at the planet’s north pole, carry electrically charged ions that pull on the planet’s magnetic field. This phenomenon, which has remained a mystery until now, has prevented scientists from measuring the length of a day on Saturn for decades.
Wow! Scientists have found that some of Saturn’s auroras are generated by swirling winds within its own atmosphere.????
Read more regarding how Saturn’s atmosphere can create auroras: https://t.co/mapIvowpb7
???? NASA / Cassini / VIMS Team / U. of Arizona / U. of Leicester / JPL / ASI / Keck. pic.twitter.com/y7dOQ4zwEU
— EarthSky (@earthskyscience) February 9, 2022
And since the clouds move on their own, looking at the gaseous planet from afar won’t tell you how fast it’s spinning. Instead, scientists measure the magnetic field, which is rooted deep in the planet’s core.
But when NASA’s Cassini probe reached Saturn in 2004, scientists were surprised to discover that the rate of radio pulses from the planet’s magnetic field had changed since it was overtaken by NASA’s Voyager 2 mission in 1981.
“The magnetic field, and the radio emissions from it, usually act like a beacon,” said James O’Dono, a planetary scientist at the Japan Aerospace Exploration Agency and co-author of the new study, which means the radio bursts come in regular pulses.
How Aurora’s look like in different planets ???? pic.twitter.com/zki10yJqjj
— Space_Hub (@SpaceHub_SL) February 5, 2022
He added: “For Saturn, this period of rotation skewed strangely over time, confusing everyone. Even stranger, the period of rotation of the planet skewed independently in the north and south.”
The study, published in the peer-reviewed journal Geophysical Research Letters, says electrically charged winds were feeding Saturn’s aurora and dragging its magnetic field all the time.
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Scientists eventually figured out how to measure Saturn’s rotation without the help of its magnetic field. They studied subtle changes in the gravitational force that the planet exerts on its rings.
In 2019, they found that Saturn completes its rotation every 10 hours, 33 minutes and 38 seconds. But the mystery of the changing magnetic field remained.
While scientists previously assumed that a double vortex polar weather pattern might be the reason behind Saturn’s moving magnetic lines, the new study is the first evidence to support this theory.
To test the theory, scientists from the University of Leicester along with a team from NASA’s Jet Propulsion Laboratory (JPL), Japan Aerospace Exploration Agency (JAXA), the universities of Wisconsin-Madison, Boston and Lancaster, as well as Imperial College London, studied and measured the aurora emissions. Infrared radiation from the gas giant’s upper atmosphere using the Keck Observatory in Hawaii mapped the changing flows of Saturn’s ionosphere, far below its magnetosphere, over the course of a month in 2017.
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Most planets, including Earth, get auroras from electrically charged particles in space, and these particles result from either interaction with charged particles from the Sun (as in Earth) or volcanic material erupting from a moon orbiting the planet (as in Jupiter and Saturn). ). These particles are captured by the planet’s magnetic field and directed toward the poles, where they interact with gases in the atmosphere to create colorful dancing lights.
In the case of Saturn, winds in the upper atmosphere, laden with electrically charged ions, create some of this interaction.
Scientists have tracked the motions of the hydrogen ion in the planet’s upper atmosphere and found that it moves in double vortices, just as weather pattern theory predicted.
Source: Business Insider
