(ORDO NEWS) — Scientists have discovered a previously unknown mechanism that causes the formation of huge auroras the size of a planet on Saturn.
This mechanism not only explains the huge auroras, but also strange periodicities in atmospheric processes.
Saturn is unique among all known planets to date in that some of its auroras are generated by eddy winds in its own atmosphere, and not just by processes in the planet’s surrounding magnetosphere.
On all other observed planets, including the Earth, auroras are formed only by powerful streams that enter the planet’s atmosphere from the surrounding magnetosphere.
They are caused either by interaction with the charged particles of the Sun (as on Earth), or by the eruption of volcanic material from a satellite orbiting the planet (as on Jupiter).
The discovery of this aurora formation mechanism changes scientists’ understanding of these phenomena and answers one of the first mysteries raised by NASA‘s Cassini probe that reached Saturn in 2004: Why can’t we easily measure the length of the day on this planet?
When the probe first approached Saturn, it attempted to measure the planet’s volumetric rotation rate, which determines the length of its day, by tracking “pulses” of radio emission from Saturn’s atmosphere.
Much to the surprise of those taking the measurements, they found that this speed appears to have changed in the two decades since the last spacecraft passed by the planet in 1981.
Since the advent of the NASA Cassini mission, several theories have been put forward trying to explain the mechanisms behind these periodic changes.
In the new study, scientists have discovered for the first time a fundamental driving force that operates in the planet’s upper atmosphere and is responsible for both the observed periodicities in Saturn’s atmosphere and the auroras.
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