The James Webb Space Telescope (JWST) has obtained images of auroras shining in Jupiter’s atmosphere. They are hundreds of times brighter than those that appear on Earth.
Auroras are formed when high-energy particles enter a planet’s atmosphere near its magnetic poles and collide with gas atoms, causing them to glow red, green, and violet colors. On Earth, the only source of these particles is solar storms. However, in the case of Jupiter, things are more complicated because of the moon Io.
Io is famous for its numerous volcanoes. They are constantly erupting, ejecting particles that, strangely enough, escape the moon’s gravity and fall into orbit around Jupiter before being picked up by its magnetic field and accelerated to high speeds. The particles crash into the planet’s atmosphere with high energy, which excites the gas and causes it to glow. Due to this combination of Io particles and solar wind, the resulting auroras are not only huge in size, but hundreds of times more powerful and brighter than the auroras on Earth.
To better understand the mechanism behind the formation of Jupiter’s auroras, the researchers engaged JWST. On Christmas Day 2023, it made a series of observations of the gas giant. The results surprised scientists. They expected Jupiter’s auroras to fade rather quickly and disappear within about 15 minutes. Instead, they saw the entire area where the auroras originated flash and shimmer with light, sometimes changing every second. The team’s findings suggest that the emission of the trihydrogen ion (H3+) is much more variable than previously thought. They will help scientists better understand how Jupiter’s upper atmosphere heats and cools.
The team also discovered several unexplained phenomena. The point is that observations of the auroras were made simultaneously by both JWST and the Hubble telescope. They were surveying in different spectral bands. Subsequent analysis showed that the brightest light observed by JWST has no real counterpart in Hubble images.
According to the researchers, this discovery made them rack their brains. To produce the combination of brightness observed by JWST and Hubble, it takes a seemingly impossible combination of a large number of very low energy particles hitting the atmosphere — like a storm of drizzle. So far, scientists don’t understand exactly how this happens.
The team plans to continue analyzing the available data, as well as engage JWST for repeat observations. Then, they will compare its images with data from the Juno spacecraft to better investigate the cause of the mysterious bright radiation. Scientists also have high hopes for the JUICE spacecraft heading toward Jupiter. It will make close-range measurements that will help better understand how the planet’s magnetic field and atmosphere interact, as well as the effects that charged particles from Io and other moons have on it.
According to NASA
