<<< >>>

The Search for Planet X


The 13-inch astrograph at Lowell Observatory
  • In 1905, Percival Lowell began noticing differences between the predicted and observed orbits of Uranus and Neptune.

  • Lowell believed these perturbations to be caused by an unseen planet beyond Neptune, predicts its estimated position.

  • The search for a 9th planet had begun at Lowell Observatory in Flagstaff, Arizona.

  • In 1908 Pickering analyzes the data and finds a new estimated position, as does Ketakar in 1911.

  • 1929: Clyde Tombaugh begins working at Lowell Observatory.