Just as Earth has spectacular auroras, so do other planets in the Solar System have their own versions of the atmospheric light show.
In fact, Jupiter has the strongest auroras in the solar system – invisible to our eyes, but shining brightly in ultraviolet wavelengths.
Because Jupiter is so wildly different from Earth, scientists are deeply invested in learning what causes these incredible atmospheric phenomena – and they have just received a new clue. Thanks to the Juno orbiter, we have now noticed for the first time the appearance of the mysterious auroral storm of Jupiter.
Jupiter’s auroras are produced by a constant rain of high-energy electrons, often removed from Io’s atmosphere. They are accelerated along the lines of the magnetic field to the poles of Jupiter, where they fall into the upper atmosphere and interact with the gases to produce a glow.
This is different from the auroras of the Earth, which are produced by particles in the solar wind. Unlike Earth’s auroras, Jupiter’s auroras are permanent and can behave quite differently.
One of these behaviors is the dawn storm – an intense light and widening of the dawn at dawn, first observed in 1994. However, these dawn storms start on the night side of the pole and we could never see them forming. until the arrival of NASA’s Juno spacecraft.
“Observing Jupiter’s aurora on Earth does not allow you to see beyond the limb at night at Jupiter’s poles,” said astronomer Bertrand Bonfond of the University of Liège in Belgium.
“Explorations by other spacecraft – Voyager, Galileo, Cassini – happened from relatively long distances and did not fly over the poles, so they could not see the full picture. understanding what happens on the night side, where the storms of dawn are born. “
The appearance of a storm at dawn. (NASA / JPL-Caltech / SwRI / UVS / ULiège / Bonfond)
Storms at dawn are really something. They start on the dark side of the planet, rotating in sight as dawn breaks, turning Jupiter’s aurora into a bright ultraviolet beacon, emitting hundreds to thousands of gigawatts of light – at least 10 times as much. energy than the usual Jovian aurora. They persist for several hours before disappearing to more normal energy levels.
Because the two planets have such differences between their auroras, it was expected that the process that generates the dawn storm would not be different from any process seen in the auroras of the Earth. Surprisingly, however, the data in Juno’s ultraviolet spectrograph seemed strangely familiar.
“When we analyzed the entire sequence of the dawn storm, we couldn’t help but notice that the auroras of Jupiter’s dawn storm are very similar to a type of terrestrial aurora called subforms,” said astronomer Zhonghua Yao of the University of Liège.
The aurora subterraneans of the Earth are amazing to see. They occur when the Earth’s magnetosphere is disturbed by electric currents, resulting in an explosive release of energy into the ionosphere. There, the energy is dissipated like a complex, dancing aurora that can last several hours.
Under the storms they are strongly influenced by the solar wind and the orientation of the interplanetary magnetic field. But the Earth’s magnetosphere is dominated by interactions with the solar wind; Jupiter’s is filled with plasma taken from Io, which is controlled by the planet’s location.
According to the team’s analysis, Jupiter’s auroral storms are influenced by an excessive release of plasma from Io, rather than by the solar wind; but the result is the same, a disturbance of the magnetosphere that leads to an explosive release of energy.
In both cases, an accumulation of plasma and energy gradually increases the instability in the system until the boom – auroral storm.
This can only increase the understanding of auroral processes on both planets and could help us better understand the aurora on other bodies in the future – including brown dwarfs, which have auroras strong enough to detect in interstellar space, even when there is no star anywhere.
“Although the ‘engine’ of the auroras on Earth and Jupiter is very different, showing for the first time the connections between the two systems allows us to identify universal phenomena and distinguish them from the relative peculiarities of each planet,” Yao said.
“Earth’s and Jupiter’s magnospheres store energy through very different mechanisms, but when this accumulation reaches a breaking point, the two systems release this explosive energy in a surprisingly similar way.”
The research was published in AGU Advances.