Scientists find never-before-seen reason behind Saturn's auroras

The beautiful auroras visible in regions near both of the planet's poles are a sight to behold. Auroras on Earth are formed due to interaction between charged particles from the Sun and Earth's magnetic field.

Other observable planets have auroras too ofcourse. Saturn is one of them. But now scientists say thatauroras on Saturn are not formed solely due to its magnetosphere.

Space scientists in Leicester have discovered a never-before-seen mechanism. They say that swirling winds in Saturn's atmosphere contribute to the auroras on the planet.

This discovery has changed scientists' understanding of planetary aurorae and answers one of the first mysteries raised by NASA's Cassini probe, which reached Saturn in 2004: why can't we easily measure the length of a day on the Ringed Planet?

When it first arrived at Saturn, Cassini tried to measure the bulk rotation rate of the planet, that determines the length of its day, by tracking radio emission 'pulses' from Saturn's atmosphere. To the great surprise of those making the measurements, they found that the rate appeared to have changed over the two decades since the last spacecraft to have flown past the planet - Voyager 2, also operated by NASA - in 1981.

Leicester PhD researcher Nahid Chowdhury is a member of the Planetary Science Group within the School of Physics and Astronomy and corresponding author for the study.

He said, "Saturn's internal rotation rate has to be constant, but for decades researchers have shown that numerous periodic properties related to the planet - the very measurements we've used at other planets to understand the internal rotation rate, such as the radio emission - tend to change with time. What's more, there are also independent periodic features seen in the northern and southern hemispheres which themselves vary over the course of a season on the planet."

"Our understanding of the physics of planetary interiors tells us the true rotation rate of the planet can't change this quickly, so something unique and strange must be happening at Saturn. Several theories have been touted since the advent of the NASA Cassini mission trying to explain the mechanism/s behind these observed periodicities. This study represents the first detection of the fundamental driver, situated in the upper atmosphere of the planet, which goes on to generate both the observed planetary periodicities and aurorae," he added.

(With inputs from agencies)