University of Reading researchers uncovered this 2017 event in which a dense solar wind stream slammed into Jupiter, crushing its magnetosphere and generating a superheated zone across half the planet's width. Temperatures in this region soared above 500oC, a stark contrast to the usual 350oC background in Jupiter's upper atmosphere.

The findings, detailed in the latest issue of Geophysical Research Letters (Thursday, 3 April), suggest such events may strike Jupiter two to three times monthly.

"We have never captured Jupiter's response to solar wind before - and the way it changed the planet's atmosphere was very unexpected. This is the first time we've ever seen a thing like this on any outer world," said Dr James O'Donoghue, lead researcher on the project.

He added, "The solar wind squished Jupiter's magnetic shield like a giant squash ball. This created a super-hot region that spans half the planet. Jupiter's diameter is 11 times larger than Earth's, meaning this heated region is enormous."

Over the past decade, planetary scientists have closely observed gas giants like Jupiter, Saturn, and Uranus, and this research highlights their susceptibility to solar events. Jupiter, the largest of them, offers a natural laboratory to study how solar storms impact planetary systems, with insights applicable to Earth-bound concerns such as satellite disruptions and power grid vulnerabilities.

The study leveraged a combination of terrestrial observations from the Keck telescope, measurements from NASA's Juno probe, and solar wind simulations. These data revealed that just before the Keck telescope's observations began, a compact region of solar wind had severely compressed Jupiter's vast magnetic field. This compression appears to have triggered intense auroral heating near the poles, driving superheated gases toward the equator and expanding the upper atmosphere.

Previously, scientists believed that Jupiter's rapid spin would contain auroral heating within the polar zones due to strong atmospheric currents. However, this discovery challenges that notion, revealing that solar-driven forces can redistribute heat globally, altering the dynamics of gas giant atmospheres in significant ways.

"Our solar wind model correctly predicted when Jupiter's atmosphere would be disturbed. This helps us further understand the accuracy of our forecasting systems, which is essential for protecting Earth from dangerous space weather," said Professor Mathew Owens, a co-author of the study.

Research Report:Sub-Auroral Heating at Jupiter Following a Solar Wind Compression

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