A few of Uranus’ obvious oddities is likely to be resulting from unhealthy timing.

In 1986, the Voyager 2 spacecraft flew previous the planet, recording mysteries of its magnetic subject. Seems, Uranus could have simply been in an uncommon state. A photo voltaic wind occasion days earlier than the flyby compressed the enormous planet’s magnetosphere, researchers report November 11 in Nature Astronomy. That compression might clarify a number of long-standing puzzles about Uranus and its moons, and will inform planning for future missions (SN: 4/20/22).

“We simply caught it at this freak second in time,” says Jamie Jasinski, an area plasma physicist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “When you had recognized that moving into, you’d have questioned every little thing that Voyager 2 measured.”

Voyager 2 discovered that Uranus’ magnetosphere, the bubble of magnetism surrounding a planet, was weird. It appeared to lack plasma, a typical element of different planets’ magnetospheres. And it had inexplicably intense belts of energetic electrons.

Jasinski and colleagues seemed again at knowledge Voyager 2 collected months earlier than the flyby (SN: 2/1/86). The group discovered that the density and pace of the photo voltaic wind, a stream of charged particles emanating from the solar, elevated steadily for days.

The strain from that photo voltaic wind would have compressed Uranus’ magnetosphere, shrinking its extent from an estimated 28 occasions Uranus’ diameter to extra like 17 occasions it inside every week. The compression might account for each the shortage of plasma and the extraordinary radiation belts, Jasinski says.

In actual fact, Uranus is within the state by which Voyager 2 discovered it solely 4 p.c of the time, the group calculates. Which means a lot of what we find out about Uranus’ magnetosphere doesn’t signify a typical day there.

“We don’t actually know something about Uranus, as a result of it was a single flyby,” says Corey Cochrane, an area physicist additionally at JPL.

On the plus facet, the brand new discovering means it is likely to be simpler for some future mission to seek for oceans beneath the floor of Uranus’ moons Titania and Oberon.

Astronomers can detect oceans on icy moons in the event that they orbit contained in the magnetosphere (SN: 10/8/24). Salty water responds to the magnetic subject round it and produces its personal magnetic subject, which spacecraft can decide up. If Uranus’ magnetosphere is often larger than documented by Voyager 2, these moons needs to be nicely inside it — and due to this fact good websites to seek for subsurface seas.