January 20, 2016
A huge planet might be sitting at the edge of our solar system without ever being seen.
The world — which could be about ten times as massive as Earth — would be large enough to become the ninth planet of our solar system.
The planet hasn’t yet been seen by scientists. Instead, they have found it by watching the way that dwarf planets and other objects in the outer solar system move — their orbits seem to be disturbed by something huge but hidden sitting out there.
“If there’s going to be another planet in the solar system, I think this is it,” Greg Laughlin of the University of California, Santa Cruz told National Geographic. “It would be quite extraordinary if we had one. Fingers crossed. It would be amazing.”
If the planet exists, it is thought to be about ten times as massive or three times as large as Earth. That sort of sized planet occurs throughout the universe — but has been an obvious omission from our own.
“This would be a real ninth planet,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy. “There have only been two true planets discovered since ancient times, and this would be a third. It’s a pretty substantial chunk of our solar system that’s still out there to be found, which is pretty exciting.”
It would be around 200 to 300 times as far away from the sun is when it gets closest to the star, scientists say. It will spend some of its time as much as four times as far away as that, and an entire orbit of the sun probably takes about 20,000 years.