Decades-old mystery solved: Scientists now know how Jupiter produces its X-ray auroras

A new study led by researchers based in the U.K. and China has figured out how Jupiter produces its own version of the aurora borealis, finally solving a 40-year-old mystery.

Four decades ago, astronomers discovered that Jupiter produces bursts of X-ray flares every few minutes. Much like the northern lights and southern lights on Earth, Jupiter’s X-ray auroras would occur at the planet’s north and south poles.

The research team that was led by University College London and the Chinese Academy of Sciences published their findings in the journal Scientific Advances on Friday. They relied on images taken from NASA’s Juno satellite orbiting Jupiter, as well as X-ray measurements from the XMM-Newton space telescope that orbits Earth.

"We can never visit black holes, as they are beyond space travel, but Jupiter is on our doorstep. With the arrival of the satellite Juno into Jupiter's orbit, astronomers now have a fantastic opportunity to study an environment that produces X-rays up close,” said co-author Graziella Branduardi-Raymont in a news release.

The researchers found that the periodic vibrations in the planet’s magnetic field were creating waves of plasma. Plasma refers to gas that has become electrically charged through a process known as ionization. The gas becomes ionized from colliding into other particles around Jupiter’s environment, which causes the gas molecules to lose electrons.

Researchers say the waves of plasma send ionized sulfur and oxygen particles “surfing" along the magnetic field lines toward’s Jupiter’s poles. These particles actually originate from volcanos on Io, one of Jupiter’s moons.

The magnetic field lines guide these particles towards Jupiter’s poles, where they crash into the atmosphere. The impact of this crash produces vivid bursts of X-rays that create this aurora effect, releasing hundreds of gigawatts of energy.

"We have seen Jupiter producing X-ray aurora for four decades, but we didn't know how this happened. We only knew they were produced when ions crashed into the planet's atmosphere,” said co-lead author William Dunn.

“Now we know these ions are transported by plasma waves - an explanation that has not been proposed before, even though a similar process produces Earth's own aurora.”​

On Earth, magnetic field lines also guide ionized particles towards the north and south poles. When these particles collide with Earth’s atmosphere, that’s when we see bright lights. However, unlike Jupiter, the particles that form Earth’s auroras originate from solar winds.

Co-lead author Zhonghua Yao says similar phenomena could potentially be present on other planets.

"Now we have identified this fundamental process, there is a wealth of possibilities for where it could be studied next,” he said in a news release. “Similar processes likely occur around Saturn, Uranus, Neptune and probably exoplanets as well, with different kinds of charged particles 'surfing' the waves."