The image that we’re showing is built up from infrared data acquired by the Keck telescope in Hawai’i, and it shows how Saturn’s south pole can be ringed with strong aurorae. Using a month of data, researchers were able to map circulation patterns in Saturn’s atmosphere that reveal the aurorae are driven by atmospheric winds and generate radio emission pulses that have made the measurement of Saturn’s rotation rate harder than it should have been. The radio pulses actually make Saturn look like it rotates with a variable-length day, but it doesn’t. It just has variable winds that generate changing aurora.

This kind of aurora is very different from what we have on Earth but actually matches early explanations for Earth’s aurorae. According to study coauthor Tom Stallard: This search for a new type of aurora harks back to some of the earliest theories about Earth’s aurora. We now know that aurorae on Earth are powered by interactions with the stream of charged particles driven from the Sun. But I love that the name Aurora Borealis originates from the ‘the Dawn of the Northern Wind.’ These observations have revealed that Saturn has a true Aurora Borealis – the first-ever aurora driven by the winds in the atmosphere of a planet.

This work appears in Geophysical Research Letters and with first author Nahid Chowdhury.

More Information

Keck Observatory press release

“Saturn’s Weather-Driven Aurorae Modulate Oscillations in the Magnetic Field and Radio Emissions,” M. N. Chowdhury et al., 2021 December 28, Geophysical Research Letters