For the first time, a three-dimensional map of the upper layers of Uranus's atmosphere has been created. This map reveals how temperatures and the concentration of charged particles change with altitude, and also shows how the planet's unusual magnetic field shapes auroras and influences Uranus's cooling over decades. The data obtained provide new insights into the evolutionary processes of exoplanets.

Uranus is an ice giant with one of the most unusual magnetic fields in the Solar System. Unlike Earth, Uranus's magnetic field is tilted, offset from the planet's center, and does not align with its axis of rotation. Using the NIRSpec spectrograph on the James Webb Space Telescope, scientists were able to visualize the upper atmospheric layer of Uranus—the ionosphere. This layer extends up to 5,000 kilometers above the clouds, where gases undergo ionization. In the ionosphere, intense interactions with the magnetic field occur, manifesting as faint infrared emissions.

Auroras on Uranus appear when charged particles travel along magnetic field lines and collide with gases in the upper atmosphere, causing them to glow. Near the magnetic poles, two bright auroral bands have been detected, separated by a region with lower ion density and weaker emissions. This may be linked to changes in the movement of charged particles and transitions between magnetic field lines. Similar structures have also been observed on Jupiter.

This discovery advances our understanding of how magnetic fields affect planetary atmospheres and helps researchers study the structure of ice giants like Uranus, as well as interpret data from distant exoplanets more accurately.