Everything we know about Uranus’ radiation belts came from one short flight by Voyager 2 in 1986, when it flew past Uranus. For decades, scientists have been puzzled by what Voyager saw. Uranus had very strong bands of high-energy electrons, but surprisingly weak bands of ions. That combination didn’t make much sense.In this study, “Unraveling the mystery of Uranus’ electron radiation belts: Utilizing knowledge of Earth’s radiation belts to reexamine Voyager 2 observations”argue that this mystery may exist because Voyager 2 did not observe Uranus under normal conditions.Recent studies show that a large disturbance in the solar wind hit Uranus during the flyby. This commotion was Corotational interaction region The CIR is a region where faster solar winds meet slower winds and stir everything up.We know that on Earth, these solar wind disturbances can dramatically activate the radiation belts. The authors suggest that the same thing happened on Uranus.

Solar wind disturbances may have supercharged Uranus during Voyager 2’s 1986 flyby

When solar wind disturbances hit a planet’s magnetic field, they can cause powerful electromagnetic waves called chorus waves. These waves act like cosmic accelerators. They repeatedly “kick” the electrons, pushing them to very high energies.Voyager 2 detected the strongest chorus waves ever seen on any planet during its encounter with Uranus. This is important because on Earth, such waves are known to rapidly boost electrons to near-relativistic speeds.So the idea is simple.

The ions remained weak and did not react.

Ions do not respond to chorus waves like electrons. Therefore, while the electrons were efficiently enhanced, the ion belt remained relatively dark. This explains the long-standing disagreement between the two.

Why Uranus is special

Uranus has an extremely tilted axis of rotation and a very oddly shaped magnetic field. This results in an unusual and constantly changing interaction with the solar wind. Therefore, its radiation environment is highly dynamic and difficult to understand from a single flight.Voyager 2 may even have passed through a sparsely populated region of the magnetosphere and lost its “normal” plasma state entirely. Uranus’ powerful electron radiation belts may not be typical at all. It may reflect temporary conditions caused by storms, similar to those seen on Earth during solar wind disturbances.

Why is this important now?

If this explanation is correct, Uranus’ radiation belts follow the same basic physics as Earth, just in a strange magnetic environment. But one flyby is not enough to be confident. That is why this paper ends with a clear message. That means we need a dedicated Uranus-orbiting satellite to observe how the magnetosphere behaves over time, not just during single, perhaps extreme events.