Uranus is all over the
place. It spins weirdly, its magnetic field is off-center, and now we’ve just found
out it may open and shut its magnetosphere every day, too. The research by Xin Cao and
Carol Paty from the Georgia Institute of Technology was published in the
Journal of Geophysical Research: Space Physics.
Modeling the system around
Uranus, they found that its magnetosphere occasionally opens up to allow solar
wind through. This seemed to happen almost every day, about every 17 Earth
hours.
This opening and closing
happens around Earth, and it’s called magnetic reconnection – where the
magnetic field lines of our magnetosphere and the solar wind align. This
produces aurorae at its poles, and it’s likely doing the same at Uranus. But at
Earth, this process is fairly irregular. At Uranus, it seems to be much more
frequent.
“As it is tumbling around, the
magnetosphere’s orientation is changing in all sorts of directions,” Paty told
New Scientist. The planet is really weird already. It rotates at almost a
right-angle to the plane of its orbit around the Sun, something no other planet
does. This may have been caused by a collision with an Earth-sized object long
ago.
Its magnetic field is
equally weird. It’s tipped by about 60 degrees to the planet’s rotation, and is
also offset from the center by about the one-third of the planet’s 25,360-kilometer
(15,760 miles) radius. On Earth, and indeed other planets, our magnetic field
lines come from pretty near our geographic poles – although magnetic north and
south changes a bit. Not so on Uranus.
Unfortunately, though, we’ve
got very little information about the Uranus. Most of our data comes from the flyby
of Voyager 2 in 1986, our only spacecraft to ever visit this planet. NASA is
currently considering proposals to send an orbiter to Uranus in the next decade
or two, which would greatly increase our understanding.
But for now, we’ve got to
rely on models like this latest study.
This basically modeled
Uranus and its magnetosphere as a whole, and it closely matched the data
gathered by Voyager 2. It seems that the rotation of the planet might be
driving its changing magnetic field. “That’s completely different from the
Earth or any of the other planets,” Paty told Gizmodo.
Finding out more about
Uranus is important, because quite a few exoplanets seem to be somewhat
similar, or at least like Neptune.
Ice giants like this seem to
be fairly common, so if we can get to the bottom of how the ones in our own
Solar System work, we might learn a bit more about planets elsewhere.