- Uranus’ deep atmosphere is primarily composed of hydrogen. There’s still a lot to learn about it.
- james webb space telescope used the near-infrared NIRSpec instrument to take a detailed look at Uranus’ mysterious upper atmosphere for the first time.
- Observations reveal new clues About Uranus’s ionosphere and powerful auroras.
Uranus’s upper atmosphere
Uranus’ deep atmosphere is primarily composed of hydrogen. For the first time, scientists have mapped the vertical structure of the upper atmosphere in three dimensions. American and British researchers said On February 19, 2026, they james webb space telescope It will measure how temperature and charged particles change with altitude in the region. Additionally, the observations also revealed auroras formed by the planet’s strong but tilted magnetic field.
new peer reviewed The result is published in Geophysical Research Letters February 19, 2026.
View Uranus’s upper atmosphere in 3D
Webb used a near-infrared spectrometer (NIR spec) An instrument for observing the upper region of Uranus’ atmosphere. It observed the planet rotate almost completely. I could see the faint glow of molecules in the top layer of the cloud.
Additionally, Webb mapped the temperature and density of ions in the upper atmosphere. This region extends approximately 3,000 miles (5,000 km) above the highest clouds. This is where the atmosphere becomes ionized. As a result, they interact with the planet’s magnetic field to produce auroras, just like Earth. In fact, scientists have observed auroras on every planet in the solar system except Mercury.
Webb found that temperatures in the upper atmosphere peak at altitudes of 1,900 to 2,500 miles (3,000 to 4,000 km). Ions, on the other hand, are most dense at altitudes around 600 miles (1,000 km).
paola tiranti Researchers from Northumbria University in the UK led a new study of Uranus’ upper atmosphere. she said:
This is the first time that we have been able to see Uranus’s upper atmosphere in three dimensions. Webb’s sensitivity allows us to track how energy moves upward through a planet’s atmosphere and even see the effects of a polarized magnetic field.
The observations provide new clues about how Uranus’ auroras form and how the planet’s strangely tilted magnetic field affects them.
Time-lapse rotation of Uranus’ upper atmosphere as seen by Webb. via video ESA/ Webb/ NASA/ CSA/ STScI/ P. Tiranti/ H. Melin/ M. Zamani (ESA/Webb).
Uranus’ atmosphere is still cooling
Remarkably, Webb also discovered that Uranus’ atmosphere is still cooling. Scientists first noticed that temperatures were starting to drop in the early 1990s. Now, Webb’s measurements show that the atmosphere is about 426 Kelvin cooler than previous measurements from both ground-based telescopes and astronomical objects. Voyager 2 spacecraft.
Additionally, Webb mapped the auroras in Uranus’ upper atmosphere. Two bright auroral bands were visible near the planet’s magnetic poles. Webb also saw a “dark area” between the two auroral bands. In these regions, the luminescence and ion density are clearly reduced. The researchers said this was likely related to changes in magnetic field lines. Jupiter has similar dark regions, with powerful auroras at its poles. and the earth similar magnetic field lineslike a giant magnet. Even though we can’t see them, they emanate from the poles and wrap around the Earth.
strange magnetosphere
Overall, the new observations reveal how unusual and complex Uranus’s upper atmosphere, and especially its magnetosphere, is. Mr. Tiranti said:
Uranus’ magnetosphere is one of the strangest in the solar system. Because they are tilted and offset from the planet’s axis of rotation, the auroras traverse the Earth’s surface in complex ways. Webb showed us how deep those effects reach into the atmosphere. By revealing Uranus’s vertical structure in such detail, Webb is helping us understand the ice giant’s energy balance. This is an important step toward clarifying the characteristics of giant planets outside our solar system.
Conclusion: The James Webb Space Telescope has mapped Uranus’s upper atmosphere for the first time. Clues about Uranus’ ionosphere and powerful auroras have been discovered.
Source: JWST discovers vertical structure of Uranus’ ionosphere
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