Uranus collage (January 2025, annotated)

For the first time, an international team of astronomers have mapped the vertical structure of Uranus’s upper atmosphere, uncovering how temperature and charged particles vary with height across the planet. Using Webb’s NIRSpec instrument, the team detected the faint glow from molecules high above the clouds. These unique data provide the most detailed portrait yet of where the planet’s auroras form, how they are influenced by its unusually tilted magnetic field, and how Uranus’s atmosphere has continued to cool over the past three decades. The results offer a new window into how ice-giant planets distribute energy in their upper layers.

Two bright auroral bands were detected near Uranus’s magnetic poles, together with reduced emission and ion density in part of the region between the two bands (a feature likely linked to transitions in magnetic field lines).