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| A complete reconstruction of what the northern and southern auroras looked like to the Juno Ultraviolet Spectograph (UVS) as Juno approached Jupiter, passed over the north pole, rapidly traveled to the southern hemisphere to pass over the southern pole, and receded from Jupiter. Credit: BERTRAND BONFOND. |
Evidence from the Juno probe’s close flights past Jupiter indicate that the gas giant’s dazzling polar light shows are caused by a mysterious mechanism different from the one responsible for intense auroras here on Earth.
On Jupiter, as on Earth, the northern and southern lights are produced by charged particles from the Sun colliding with gas atoms in the atmosphere and releasing energy in flashes of light.
Jupiter’s aurora is the brightest in the solar system, so planetary scientists assumed it was produced by the discrete process.
However, a paper in Nature analyzing data from Juno’s low-altitude passes over Jupiter’s poles shows that, while there are extremely intense electric fields aligned with the magnetic field and signs that electrons are being accelerated downwards, the resulting auroras were much dimmer than those produced by the broadband process.
Why? The authors don’t know, though they speculate that Jupiter’s intense auroras may be started by a discrete process creating a stream of electrons that is then disrupted and diffused by the magnetic field fluctuations that produce the broadband process.
Power supply for Jupiter’s aurora puzzles scientists, Michael Lucy, COSMOS magazine
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