"This would be a real ninth planet. 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."—Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy
The giant planet, discovered through mathematical modeling and computer simulations, is nicknamed Planet Nine and traces a bizarre, highly elongated orbit in the outer solar system.
California Institute of Technology - Caltech researchers say there may be an unseen planet that's about 10 times more massive than Earth.
You might have a replacement, Pluto. There could be ninth planet in our solar system again: "Planet Nine," as researchers call it.http://cnn.it/1nyPVub
Astronomers have found evidence suggesting the solar system may have a ninth planet