In 1930, the planet Pluto was discovered by Clyde Tombaugh, when comparing two photographic plates taken six days apart the previous month. He found a starry speck that changed position between them. The search for Planet X was started three decades earlier (before Tombaugh was born) at Lowell Observatory in Flagstaff, Arizona, by Percival Lowell. Deviations in the positions of Uranus and Neptune were suspected to be due to the gravity of an undiscovered ninth planet. Locating it meant sifting through the millions of star images for one dim dot that moved. Lowell was unsuccessful, but in his will decreed that the hunt should continue. Clyde Tombaugh was a Kansas farmboy when Lowell Observatory director Vesto Slipher hired him in 1929. Pluto was the only planet found by an American
