Mysteries of Uranus may be explained by extreme space weather

Mysteries about Uranus that have puzzled scientists for decades could result from unexpected data collected during an unusually powerful solar storm, research suggests.

In 1986, NASA’s Voyager 2 flew past the seventh planet in the solar system, giving scientists their first and only glimpse of Uranus and shaping their understanding of it ever since.

However, there were some unexpected findings, which experts now believe were due to a period of extreme space weather at the time of the flyby.

They suggest that this solar storm likely crushed the planet’s magnetic bubble, pushing out plasma and intensifying radiation belts – regions of charged particles stuck on magnetic field lines.

Experts say they now know even less about a typical day on Uranus, and they need a second spacecraft to visit the planet to learn more.

The flyby’s findings indicated that the planet’s radiation belts were incredibly intense, second only to Jupiter’s.

Yet the rest of Uranus’ magnetosphere (magnetic bubble) was virtually empty of plasma (gas atoms or molecules with an electric charge), meaning there was no obvious source of charged particles to feed those belts.

Because of the nearly empty magnetosphere, Uranus’ five moons were believed to be inert dead worlds, with no continuous activity.

However, the new findings, published in Nature Astronomy, suggest they could be active after all and possibly even have oceans.

Co-author Dr William Dunn, from UCL’s Department of Physics and Astronomy, said: “Almost everything we know about Uranus is based on Voyager 2’s two-day flyby.

“This new study shows that much of the planet’s bizarre behavior can be explained by the magnitude of the space weather event that occurred during that visit.

“We now know even less than we thought about what a typical day in the Uranian system might look like and are even more in need of a second spacecraft to truly understand this mysterious, icy world.

“A key piece of evidence against the existence of oceans on the moons of Uranus was the lack of detection of water-related particles around the planet – Voyager 2 found no water ions.

“But now we can explain that: the solar storm would actually have blown away all that material.”

Dr. Linda Spilker, who works at NASA’s Jet Propulsion Laboratory, was one of the scientists on the Voyager 2 mission.

She said: “The flyby was full of surprises and we were looking for an explanation for its unusual behaviour.

“Voyager 2’s measured magnetosphere was just a snapshot.

“This new work explains some of the apparent contradictions, and it will once again change our view of Uranus.”

A possible NASA space mission to Uranus is currently being developed after the US National Academies’ Planetary Science and Astrobiology Decadal Survey 2023 prioritized the planetary system as a target for a future mission.

Voyager 2 is now in interstellar space, about 13 billion miles from Earth.