Writing in the Geophysical Research Letters, NASA says a review of Voyager 2’s old data from 1986 showed that Uranus vented a giant blob of gas into space. This pocket of ionized gas, a plasma structure called plasmoid, was 400 km across and 200 km long.

According to NASA’s news release, Uranus is special in that it spins almost on its side “like a pig on a spit roast,” while the axis of its magnetic field is offset from the spin by 60 degrees. This gives the planet’s magnetic field an odd wobble that scientists cannot model.

As solar winds blasted Uranus, the bombardment pinched gas off from the far end of the field. The resulting leak was then accidentally discovered by NASA researchers who were reviewing the old magnetic data.

In the new research, scientists dialed up the reading’s resolution to make a data point every two seconds. They spotted a blip in the readings that indicated the planet was making a plasmoid.