New observations of Ganymede reveal a striking similarity between the auroras on the largest moon in the solar system and those on Earth. The international team of astrophysicists, led by researchers from the University of Liège, has produced new results indicating that, despite different conditions, the fundamental physical processes that generate auroras are common to different celestial bodies, and not just planets.

A team of astrophysicists from the Laboratory of Atmospheric and Planetary Physics (LPAP) has observed for the first time the fine details of the auroras on Ganymede, the only moon in the solar system to have its own intrinsic magnetic field, similar to that of Earth. The observation of auroras is a cornerstone of space weather analysis, as it provides a comprehensive view of the characteristics and effects of space particle precipitation into atmospheres.

For centuries, humanity has witnessed a diffuse and changing glow that occasionally illuminates the night sky with red, green, purple and blue lights—known as the “aurora.” Auroras are typically observed at polar latitudes, although we have just passed the peak of the 11-year solar cycle, which is producing many instances of intense auroras at mid-latitudes.

“This is the first time we’ve been able to see Uranus’s upper atmosphere in three dimensions,” said Paola Tiranti.

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What does the atmosphere of Uranus look like? This is what a recent study published in Geophysical Research Letters hopes to address as a team of researchers from the United States and United Kingdom investigated new data about the upper atmosphere of Uranus. This study has the potential to help scientists better understand the atmosphere of Uranus and establish new methods for exploring gas giant atmospheres.

For the study, the researchers analyzed data obtained from NASA’s James Webb Space Telescope (JWST) in January 2025 with its powerful infrared instruments. The motivation for the study was due to the lack of understanding of Uranus’s upper atmosphere, whose temperature and composition have remained elusive. The researchers focused on a region of the upper atmosphere known as the ionosphere, which is the region that interacts with the space environment and produces the auroras.

In the end, the researchers not only created the first 3D map of Uranus’s upper atmosphere, but found that atmospheric temperatures peak between 3,000 to 4,000 kilometers (1,864 to 2,485 miles) above the planet while the density of charged particles, where space radiation interacts with the atmosphere, peak at approximately 1,000 kilometers (621 miles) above the planet. Additionally, the researchers were surprised to discover that the charged particle density was weaker than longstanding models had predicted.