The discovery of new planets in the last two hundred years owes more to mathematics than to bigger telescopes. Mathematical irregularities in the orbits of the outer planets, in particular, strange wobbles and gravitational anomalies noted in the orbits of Uranus, Neptune and Pluto, have prompted astronomers over the past hundred years to search for a large planetary body in the outer solar system. Based on mathematical evidence, astronomers have been so sure of the reality of this planet that they named it Planet X.

The Planet X Video
http://www.planetxvideo.com