The solar system may host a ninth planet that is about 10 times bigger than Earth and orbiting far beyond Neptune, according to research published on Wednesday.
Computer simulations show that the mystery planet, if it exists, would orbit about 20 times farther away from the sun than Earth, said astronomers with the California Institute of Technology in Pasadena.
So far, the planet has not been observed directly.
"It's a pretty substantial chunk of our solar system that's still out there to be found, which is pretty exciting,” astronomer Mike Brown said in a statement.
The research is published in this week’s Astronomical Journal.
(Reporting by Irene Klotz; Editing by Bill Trott)