Evidence of a Ninth Planet

Caltech planetary astronomer Mike Brown and colleague Konstantin Batigin have proposed the existence of a ninth planet in the solar system. They observed that the most distant objects beyond Neptune and Pluto all swing out in one direction, suggesting the presence of a massive planet that keeps them in place while they orbit the sun. This proposed planet, which should be more massive than Earth but less massive than Neptune, is a new discovery since we have nothing like it in our solar system.