Astronomers recently observed a rare phenomenon on Jupiter: Both of its auroras were active at the same time, producing high energy X-ray pulses. But to their surprise, the north and south auroras pulsed independently. This differs from what researchers expected to see—and is not how auroras behave on Earth, reports Rachel Becker at The Verge.
Auroras occur when gas molecules in the upper reaches of the atmosphere interact with charged particles emitted from the sun during solar flares. On Earth, this creates radiation in the form of visible light, producing the Aurora Borealis and the Aurora Australis. But as Becker explains, they also produce infrared, ultraviolet and X-ray radiation, though the X-rays for Earth's light shows are weak.
Other large planets like Saturn do not produce X-ray auroras, making Jupiter's X-ray hotspots are unusual, according to a press release. That’s why the European Space Agency’s XMM-Newton space-based X-ray telescope and NASA’s Chandra X-ray observatory took a look at Jupiter's auroras. They found that the burst from the south pole pulsed every 11 minutes while the pulses from the north were erratic. The research appears in the journal Nature Astronomy.
“We didn't expect to see Jupiter's X-ray hot spots pulsing independently as we thought their activity would be coordinated through the planet's magnetic field, but the behavior we found is really puzzling,” says lead author William Dunn, researcher at the UCL Mullard Space Science Laboratory and Harvard-Smithsonian Center for Astrophysics, in the release. “We need to study this further to develop ideas for how Jupiter produces its X-ray aurora and NASA's Juno mission is really important for this."
As Becker reports, Jupiter’s aurora is a lot more complicated than Earth’s. The planet is not only bombarded by particles from the sun but also gets a dose of charged molecules—including oxygen and sulfur—from its volcanic moon Io. Those highly charged particles line up with the planet’s magnetic field and are then accelerated by the planet’s 28,273 mile-per-hour rotation. When they strike atmospheric particles they strip away electrons and produce high-energy X-rays.
Because magnetic field lines make an arc connecting the poles of a planet, it’s thought that whatever impacts one part of the magnetic field would affect the field as a whole. But the difference in the X-ray pulses in the north and south show that isn’t happening on Jupiter.
To figure out just what the deal is, the researchers hope to combine the data from the X-ray observers with data from NASA’s Juno Explorer, which has been observing the gas giant since last year. According to the press release, researchers hope to correlate physical processes on the planet with the X-ray data to understand the mismatched auroras.
It’s believed that a magnetic field that shields a planet from solar radiation is a necessary ingredient for the development of life. Learning about different types of magnetic fields can help researchers in the search for life in other parts of the universe. “If we’re going to search other planets for other life, then we’re going to want to find places that have magnetic fields,” Dunn tells Dana Dovey at Newsweek. “Understanding in our Solar System what the signatures for northern lights are and what they mean is important, because hopefully at some point in the future, we’ll be looking at these signatures at extra-solar planets.”
Hopefully Juno helps clear up the mystery. If not, it may be a while before we figure out what’s up with Jupiter's light show. Researchers won't get more detailed data until 2029, when the ESA’s Juice probe arrives at the planet to investigate its atmosphere and magnetosphere.