Scientists are getting closer to solving a mystery about Uranus’ powerful radiation belt. A new look at data from Voyager 2 suggests that a temporary space weather event may have intensified the planet’s electron radiation belt while the spacecraft was passing by.
Radiation belts form from interactions between a planet’s magnetic field and the solar wind, a stream of charged particles from the sun. Earth and Uranus both have magnetic fields that trap these energetic particles in their magnetospheres.
When Voyager 2 flew by Uranus in January 1986, it measured the radiation belts. Surprisingly, while the ion radiation belt was weaker than expected, the electron radiation belt was much stronger, nearing the maximum intensity that Uranus could sustain. Since then, researchers have been trying to understand why.
“Science has advanced a lot since the Voyager 2 flyby,” says Robert Allen, a space physicist at the Southwest Research Institute. He and his team compared Voyager 2’s data with Earth’s observations, particularly from a 2019 space weather event.
In their study, published in *Geophysical Research Letters*, the team found striking similarities. They suggest that a phenomenon known as a “co-rotating interaction region,” which happens when fast solar winds catch up to slower ones, may have boosted the energy in Uranus’ radiation belt. This could explain the increased intensity observed by Voyager 2.
“In 2019, Earth experienced a similar event that caused a significant surge in radiation belt electrons,” says Sarah Vines, another co-author of the study. “If something like that happened at Uranus, it could explain the unexpected energy levels Voyager 2 detected.”
This raises more questions about Uranus’ magnetosphere and how it interacts with the solar wind, especially during its extreme seasonal changes due to its tilted axis. A future mission to Uranus could help answer these questions by gathering data from different parts of its magnetosphere.
“All these findings underline the need for a mission targeting Uranus,” Allen emphasizes. “It could help us learn more about similar systems, like Neptune.”
Experts agree that understanding Uranus’ radiation belts could provide insights not just about this distant planet, but also about other celestial bodies with magnetic fields. As we continue to explore space, each discovery brings us closer to understanding our solar system better.
For more detailed insights, you can check the research paper by Allen, Vines, and Ho from 2025 [here](https://doi.org/10.1029/2025gl119311).
