http://www.msnbc.msn.com/id/47522725.../#.T7z3Zr9wbGs
It could be a planet larger than Earth way out on the edge of the solar system.
The outer planets irregulare orbits have long made astronomers believe that there could be another larger planet much further out than Neptune.
If true, and this discovery had been made in the 1980's, this planet would have been Planet X, or the 10th Planet.
As it is, it is would only be the 9th Planet again, basicly replacing Pluto.