Jupiter’s auroras are the most powerful in the solar system, producing enough energy to briefly power all of human civilisation.
Key points:

  • Jupiter produces powerful x-ray auroras at its poles
  • For decades, scientists have been puzzled about how these auroras are produced
  • A new study has found that vibrations in the planet’s massive magnetic field play a key role in generating x-ray auroras

These spectacular light shows also emit x-rays, which glow purple.
But since being discovered 40 years ago, scientists have struggled to work out how they were created.
“We’ve seen these really weird things happening at Jupiter’s poles for decades,” said William Dunn, an astronomer at University College London. 
“But we had no idea why.”
Now, Dr Dunn and an international team may have the answer. 
They discovered that vibrations in Jupiter’s magnetic field create powerful waves that carry supercharged particles to the planet’s poles.
These particles smash into the atmosphere creating a bright burst of x-rays.
Their findings were published today in Science Advances.
Magnetic field vibrations
To find out how Jupiter’s x-ray auroras are generated, Dr Dunn and colleagues analysed measurements collected by NASA’s Juno space probe, which has been orbiting Jupiter since 2016.
The researchers also used images of the planet’s x-ray auroras captured by the European Space Agency’s XMM-Newton space telescope, which orbits Earth.
Vibrations in Jupiter’s magnetic are a key part of generating its amazing x-ray auroras.(Supplied: NASA Chandra/Juno Wolk/Dunn
First, they noticed that Jupiter produced x-ray auroras every 27 minutes. 
“You can set your watch by it,” Dr Dunn said.
The next step was looking for something else that matched these clockwork-like pulses. 
They found that Jupiter’s magnetic field vibrated in sync with the x-ray flashes, indicating that the two were connected.
The team found that the vibrations in the gas giant’s magnetic fields created special waves called electromagnetic ion cyclotron waves, which also play a role in our own northern and southern lights.
The particles ride these waves to the poles and generate auroras when they collide.
The particles that fuel the auroras
Earth’s auroras only occur during solar storms, when the solar wind  a stream of charged particles from the Sun rains down on the planet’s magnetic field.
These particles ride along the magnetic field’s lines towards the poles in waves where they smash together and create glowing curtains of light in the sky. 
Earth’s auroras only occur during solar storms, whereas Jupiter’s are permanent. (Wikimedia Commons: NASA
“Earth’s auroras are really at the whim of whatever the solar wind is doing and are completely controlled by it,” Dr Dunn said.
On the other hand, Jupiter’s auroras happen all the time and are mainly fuelled by oxygen and sulphur particles spewing out from the giant volcanoes on its nearby moon, Io.
This continuous stream of particles surf the electromagnetic ion cyclotron waves along the lines of the magnetic fields to the poles.
Once there, the particles smash together, producing spectacular bursts of x-rays to the regular vibrations of the magnetic field.
“This isn’t something that had ever been proposed before for Jupiter,” Dr Dunn said
Connecting to the bigger picture
The fact that both Jupiter and Earth’s auroras are powered by these special waves suggests they could also play a role in the rest of the universe.
“Even though their systems are so different in every way imaginable, it’s hinting that there’s a universal process,” Dr Dunn said.
“Whatever the environment, these waves are able to move energy and particles around in that environment.”
Want more science plus health, environment, tech and more? Subscribe to our channel.
This means that a similar process could be driving auroras on other planets, from Uranus to Saturn.
Lucyna Kedziora-Chudczer, an astronomer at the University of Southern Queensland, said more work is needed to fully understand how Jupiter creates its spectacular auroras.
“Jupiter is pretty much a natural laboratory for us to test various ideas about how these electromagnetic waves interact with these charged particles,” said Dr Kedziora-Chudczer, who was not involved in the study.
“This is one piece of the puzzle.”
Want more science from across the ABC?
Science in your inbox
Get all the latest science stories from across the ABC.