Researchers uncover solar wind event that may explain Uranus’ strange magnetic behavior

Space.com reports that new analysis of Voyager 2 data suggests Uranus may have been experiencing a strong solar wind event during the spacecraft’s 1986 flyby.

Researchers revisited the measurements almost 40 years later and found signs that a fast stream of solar wind may have collided with a slower one, forming what is known as a co-rotating interaction region.

This type of event can change a planet’s magnetic space environment. The study team says this could explain why Voyager 2 recorded compressed magnetic fields, very little plasma, and unusually energetic electrons when it passed the planet.

In the report, study lead Robert Allen said, “Science has come a long way since the Voyager 2 flyby,” noting that new tools allow scientists to compare old data with what is now known about space weather at Earth.

Co-author Sarah Vines added that a similar event at Earth in 2019 led to “an immense amount of radiation-belt electron acceleration,” which may match what Voyager 2 observed at Uranus.

By placing the old information in a new context, researchers suggest that Uranus may not always appear as it did during the 1986 encounter. This work supports the growing call for a new mission to study the planet up close.

What does the new analysis from Voyager 2 show?

The new study compares Voyager 2 measurements with later observations of similar solar wind events at Earth.

Researchers found several patterns that match what happens when a co-rotating interaction region reaches a planet. These patterns include compressed magnetic fields and stronger electron activity.

According to the team, “a fast wind stream interacting with a slow one can produce the same type of shock structure” seen in the Voyager 2 records.

The comparison helps explain why Uranus’ magnetosphere looked squeezed and why its radiation belts contained many energetic electrons.

The scientists also revisited past assumptions. In 1986, many thought such a solar event would push electrons into a planet’s atmosphere. New findings from Earth studies show that these events can instead add energy to radiation belts.

As Vines explained, “the mechanism can increase electron acceleration rather than scatter it away.” This idea fits well with the high electron levels Voyager 2 detected.

The analysis suggests that the strange readings at Uranus were likely temporary and not the planet’s usual condition.

The team argues that consistent monitoring or a return mission would be needed to see how Uranus behaves under normal space-weather conditions.

Why do the findings matter?

The study highlights how much information remains in older mission data. Since Voyager 2 is still the only spacecraft to visit Uranus, researchers must continue using its records to understand the planet.

Allen noted that “this is one more reason to send a mission targeting Uranus,” because a single short flyby cannot show how the planet changes over time.

A new mission could observe how often solar wind events reach Uranus and how the planet’s tilted magnetic field responds.

These findings also help compare Uranus with Neptune. Voyager 2 later found that Neptune’s magnetic field is also tilted and offset from the planet’s center.

The new analysis suggests that both planets may react strongly to solar wind structures. If so, this could shape how scientists model ice giants in our solar system and beyond.

As the authors point out, the results “have important implications for similar systems,” meaning other planets with unusual magnetic fields may show the same responses.

The work supports ongoing discussions about future missions. NASA has listed a Uranus orbiter as a top priority.

A long-term visit would help confirm whether the 1986 event was rare or a recurring feature of Uranus’ environment.
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