Just as Earth has amazing auroras, so too do other Solar System planets have their own versions of the atmospheric light display.
Jupiter, of course, has the most powerful auroras in the Solar System – invisible to our eyes, but shining brilliantly in ultraviolet waves.
Because Jupiter is so wildly different from Earth, scientists have invested heavily in learning what drives these amazing atmospheric onions – and they just got a new insight. Thanks to the orbiter Juno, we have now seen for the first time the mysterious auroral storm of Jupiter.
Jupiter auroras are emitted by a steady stream of high-energy electrons removed from Io’s atmosphere. These are accelerated along magnetic field layers to the Jupiter poles, where they fall into the upper atmosphere and interact with the gases to make glue.
This is in contrast to the Earth ‘s auroras, which are made up of particles from the solar wind. Also unlike Earth’s auroras, Jupiter’s auroras are durable, and can behave quite differently.
One of these behaviors is the storm of the day – the brightening and intense expansion of the aurora at daybreak, first seen in 1994. However, these morning storms begin on the night side of the pole, and do not we had never seen them form until NASA’s Juno probe reached the scene.
“Observing Jupiter’s aurora from Earth will not let you see beyond the border, into the night side of Jupiter’s poles,” explained astronaut Bertrand Bonfond of the University of Liège in Belgium.
“A study by another spacecraft – Voyager, Galileo, Cassini – took place from relatively large distances and did not travel over the poles, so they could not see the full picture. That is why Juno’s data is true player-player, giving us a better understanding of what happens on the side of the night, where the storms of the day are born. “
A storm surges. (NASA / JPL-Caltech / SwRI / UVS / ULiège / Bonfond)
Dawn storms are definitely something. They start on the nocturnal side of the planet, turning into the scene as the break of day, transforming Jupiter’s aurora into a terrifying ultraviolet light, taking away hundreds to thousands of gigawatts of light – at least 10 times as much energy as the typical Jovian aurora. They last for a few hours before entering more normal energy levels.
Given that the two planets have such large differences between their auroras, the process that generated the storm of the day was expected to be unlike any processes seen in Earth’s auroras. Surprisingly, however, the data from Juno’s ultraviolet spectrograph looked strange.
“When we look at the human storm series as a whole, we couldn’t help but notice that Jupiter’s human storm auroras are very similar to a type of terrestrial auroras called substorms,” said astronomer Zhonghua Yao of University of Liège.
The Earth’s auroral substrates are strikingly visible. They occur when electric currents disturb the Earth’s magnetosphere, as a result of which energy is released explosively into the ionosphere. There, the energy is dissipated as a complex dancing aurora that lasts several hours.
Sub-storms greatly affect the solar wind and the direction of the interplanetary magnetic field. But the Earth’s magnetosphere is largely controlled by interactions with the solar wind; Jupiter’s is filled with plasma removed from Io, which is controlled by the planet’s space.
According to the team’s study, Jupiter’s auroral drought storms are influenced by excessive plasma discharges from Io, rather than solar wind; but the result is the same, disturbance of the magnetosphere leads to the dispersal of explosive energy.
In all cases, the buildup of plasma and energy gradually increases instability in the system until it grows – an auroral storm.
This can only increase our understanding of the auroral processes on both planets, and may help us to understand aurora on other bodies in the future – including brown dwarfs, at its auroras are strong enough to be found over an intersex space, even when they are not close to a star space.
“Although the ‘engines’ of the auroras on Earth and Jupiter are very different, showing for the first time that the connections between the two systems allow us to identify universal onions and the difference from the specifics that apply to each planet, ”Yao said.
“Earth’s magnetospheres and Jupiter store energy through very different devices, but when this collection reaches a breaking point, both systems release this energy explosively in a remarkably similar way. “
The research was published in AGU Advances.