NASA’s Voyager 2 probe flew through a blob of charged gas called a plasmoid decades ago, and scientists only just now realized it.
It’s been several decades since NASA’s Voyager 2 spacecraft reached the chilly planet Uranus. The probe cruised past the frigid world at a distance of around 50,000 miles, sending back a wealth of data for scientists to dig through. Now, 34 years after it visited Uranus, the data that Voyager 2 sent back has revealed something entirely new.
As NASA reports in a new post, researchers recently discovered that Voyager 2 cruised through a blob of charged gas called a plasmoid as it passed the planet. The spacecraft’s journey through the plasmoid lasted only about a minute, but that was still long enough for scientists to spot the anomaly in the decades-old data.
Determining where the gassy blob came from was difficult, but the researchers think they have it figured out:
Readings from inside the plasmoid — as Voyager 2 flew through it — hinted at its origins. Whereas some plasmoids have a twisted internal magnetic field, DiBraccio and Gershman observed smooth, closed magnetic loops. Such loop-like plasmoids are typically formed as a spinning planet flings bits of its atmosphere to space.
The scientists believe that gas loss may have already drained as much 55% of the planet’s atmosphere. Loss of atmosphere resulting in plasmoids has been observed around other planets in our solar system, including Saturn and Jupiter, though it’s thought that Uranus has leaked far more of its gas than the rest.
Uranus is an incredibly strange planet when compared to its peers in our system. It rotates on its side, making it an immediate standout. On top of that, it has a distinct wobble that astronomers have been trying to explain for a long time. It’s believed that a massive object slammed into Uranus a long time ago, and its bizarre movement today is a direct result of that event.
“The data revealed a helical bundle of magnetic flux containing planetary plasma, known as a ‘plasmoid,’ in the tail of the magnetosphere,” the researchers write in a paper published in Geophysical Research Letters. “This first observation of a plasmoid in an Ice Giant magnetosphere elucidates processes that occur in the magnetosphere of Uranus and suggests that plasmoids may play a large role in transporting plasma.”
Only a limited amount can be learned from such a brief observation, but the scientists are making the most of it. In the future, subsequent missions past (or to) Uranus could reveal additional details about its atmosphere loss.