Mystery of Jupiter's northern lights solved after 40 years, scientists say

Jupiter's mysterious X-ray auroras have been explained by combining data from NASA's Juno mission with X-ray observations from the European Space Agency's XMM-Newton.

(CNN)The aurora borealis, or northern lights, are Earth's greatest light show, dazzling those lucky enough to see them in the northernmost reaches of our planet.

It's a phenomenon shared by other planets in our solar system, including the largest, Jupiter, which is bathed in spectacular color at its poles.
Characterized by massive pulsating X-ray flares, Jupiter's northern lights were first discovered 40 years ago. Astronomers have long sought to explain the mechanism behind these auroras. NASA has called them "a powerful mystery."
    "They are unimaginably more powerful (than Earth's) and much more complex. Jupiter's northern lights have these bright flares, and these flares can be up to terawatts of power that would power all of civilization," said William Dunn, a research fellow at University College London's Mullard Space Science Laboratory.
      He was part of an international team of scientists who say they have solved this 40-year-old mystery.
      By combining observations and data from NASA's Juno spacecraft, which launched in 2016, and the European Space Agency's X-ray telescope, the researchers found that the pulsating X-ray auroras are caused by fluctuations of Jupiter's magnetic field.
      "Probably the reason it remained a mystery for 40 years is because we hadn't had this opportunity. We've not had this beautiful and amazing spacecraft in Juno and also an X-ray telescope orbiting the Earth," Dunn said.
        The research published in the journal Science Advances on Friday.
        This image, created with data from Juno's Ultraviolet Imaging Spectrometer, marks the path of Juno's readings of Jupiter's auroras.

        Waves of particles

        On Earth, the northern lights are driven primarily by solar winds -- particles emitted during solar storms that flow out through space and tear through Earth's magnetosphere, creating a colorful light show.
        On Jupiter, there are other factors at play, Dunn said.
        Jupiter spins much faster than Earth, and it has the strongest magnetic field of any planet in the our solar system. What's more, Jupiter's third-largest moon, Io, is covered by more than 400 active volcanoes, which pump out volcanic material into Jupiter's magnetosphere, the area controlled by a planet's magnetic field.
        "The northern lights are basically the video of what's going on in the magnetosphere," Dunn said.
        Jupiter's X-ray flares were first discovered in 1979, Dunn added, which puzzled scientists because the phenomena were usually associated with more exotic space bodies like black holes and neutron stars.
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