Scientists from the University of Minnesota have discovered something extraordinary in Jupiter’s polar regions that has never been seen before, a completely new type of plasma wave that creates aurora unlike anything we observe on Earth.
While Earth’s northern and southern lights (also known as the aurora borealis and aurora australis) create familiar green and blue curtains dancing across our sky, Jupiter’s aurora is an entirely different beast. In comparison, Jupiter is vastly more magnetic, due to its large size, fast rotation, and complex interactions with its moons, make it a natural laboratory for extreme physics.
The Aurora Borealis, or Northern Lights, shines above Bear Lake (Credit : United States Air Force)
The discovery came from NASA’s Juno spacecraft, which made history as the first probe to orbit Jovian poles. What the team found challenges everything we thought we knew about aurora, which have primarily been understood through Earth based observations.
The key to this breakthrough is the nature of plasma. Plasma is a state of gas where matter is so hot that atoms break apart into electrons and ions. This then flows like an invisible ocean around Jupiter. These particles are accelerated down toward the planet, where they ignite gases in the upper atmosphere, creating the aurora phenomenon.
An illustration shows NASA’s Juno spacecraft near Io with its parent planet Jupiter in the background (Credit : NASA)
Professor Robert Lysak, a world expert on plasma waves, worked with observational astronomers Ali Sulaiman and Sadie Elliott to decode what Juno was seeing. They discovered that Jupiter’s unique conditions, an incredibly strong magnetic field combined with extremely low plasma density in its polar regions, created the never seen before phenomenon.
Alfvén waves, named after physicist Hannes Alfvén who first theorised in 1942 that plasma could behave like both a fluid and respond to magnetic fields are central to the phenomenon. The data showed that, due to the extremely low density of the plasma in Jupiter’s polar region, the frequency of the plasma waves was very low especially compared to the frequency of similar waves on Earth.
The differences between Earth and Jupiter’s auroral systems are striking. On Earth, the aurora forms a typical donut pattern of auroral activity around the polar cap, while the polar cap itself remains dark. Jupiter operates differently, thanks to its complex magnetic field system which allows charged particles to flood directly into the polar cap regions, creating aurora where Earth would have darkness.
Auroras shine bright blue over Jupiter (Credit : NASA/ESA)
Unlike Earth’s visible green and blue auroras created by oxygen and nitrogen, Jupiter’s upper atmosphere is very different from Earth’s and its aurora tends to be invisible to the naked eye and can only be observed with UV and Infrared instruments.
This discovery reveals an entirely new regime of plasma physics that couldn’t be observed from Earth based studies alone. The research expands our understanding of how plasma behaves under extreme conditions, knowledge that could have applications in fusion energy research and space weather prediction.
While Juno continues to orbit Jupiter, the team hopes future missions like JUICE and Europa Clipper, arriving at Jupiter in the late 2020s, will provide additional opportunities to study this phenomenon. Each new observation helps scientists piece together the complex puzzle of planetary magnetospheres and their role in shaping the space environment around giant planets.
Source : Alien Aurora: Lysak, Sulaiman and Elliott find new plasma regime in Jupiter’s aurora