JWST Maps Uranus’ Atmosphere, Reveals Magnetic Field Secrets & Glowing Auroras

Scientists using the James Webb Space Telescope have, for the first time, mapped the upper atmosphere of Uranus, revealing new details about the planet’s unusual magnetic field and the auroras that surge through it.

The James Webb Space Telescope (JWST) observed Uranus rotating for 15 hours – nearly a full Uranian day – to investigate how ice giants distribute energy in their upper atmospheres and how the planet’s auroras function. These observations are particularly significant given the limited prior data. Voyager 2’s flyby in 1986 provided only a brief glimpse of the planet.

A Unique Magnetic Field

Uranus’s magnetic field is unlike that of any other large planet in our solar system. Its magnetic pole is tilted by 60 degrees relative to its geographic pole. This extreme tilt results in auroras that extend far beyond the planet’s poles, a stark contrast to the auroras observed on Earth. The telescope’s data provides the most detailed portrait yet of where these auroras form and how the magnetic field influences them.

Researchers used JWST to study Uranus’s magnetosphere – the region of space around the planet dominated by its magnetic field. “Uranus’s magnetosphere is one of the strangest in the solar system,” explained Paola Tiranti, a doctoral student at Northumbria University in the U.K., in a statement. “Webb has now shown us how deeply those effects reach into the atmosphere.”

Strange Lights and Atmospheric Cooling

JWST charted the most detailed view yet of how particles in Uranus’s upper atmosphere are energized (ionized) by interactions with the sun. The study, published on February 19, 2026, in the journal Geophysical Research Letters, measured ion temperature and density as far as 3,100 miles (5,000 kilometers) above the cloud tops of Uranus.

The data revealed that temperature and density do not peak at the same altitude. Ions were warmest between roughly 2,500 and 3,100 miles (4,000 and 5,000 km), but the densest at about 600 miles (1,000 km). This is attributed to the complex geometry of the planet’s magnetic field. The geometry also produced two bright bands of auroras near Uranus’ magnetic poles, with a depletion in both ion density and auroral emissions observed in between – an effect likely caused by transitions between the planet’s magnetic field lines, similar to observations made at Jupiter.

Beyond mapping the upper atmosphere in three dimensions, JWST confirmed previous findings indicating that Uranus’s upper atmosphere has been steadily cooling since the early 1990s. The telescope measured the average temperature of Uranus’s atmosphere at approximately 307 degrees Fahrenheit (153 degrees Celsius), which is lower than previous measurements from spacecraft and ground-based telescopes.

“By revealing Uranus’s vertical structure in such detail, Webb is helping us understand the energy balance of the ice giants,” Tiranti said. “This is a crucial step towards characterizing giant planets beyond our solar system.”

Understanding Uranus is important not only for unraveling the mysteries of our own solar system but also for gaining insights into ice giant planets orbiting other stars. Uranus’s unique axial tilt – it essentially orbits the sun on its side – and chaotic magnetic field offer a valuable case study for planetary scientists seeking to understand the diverse range of planetary environments that may exist throughout the galaxy.

The observations from JWST represent a significant leap forward in our understanding of Uranus, a planet that has remained relatively unexplored for decades. Further study of Uranus and other ice giants like Neptune, will be crucial for refining our models of planetary formation and evolution, and for identifying potentially habitable worlds beyond our solar system.