How did Clyde Tombaugh find Pluto?

Clyde Tombaugh discovered Pluto in 1930 while working at the Lowell Observatory. His search was initiated by the predictions of astronomer Percival Lowell, who had spent years looking for a ninth planet, often referred to as "Planet X," to explain perceived perturbations in the orbits of other planets.12

To conduct his search, Tombaugh used a 33-cm (13-inch) telescope to capture photographic plates of the night sky. He then utilized an instrument called a blink comparator to examine these plates. This device allowed him to view two images of the same region of the sky, taken on different nights, in rapid succession. By alternating between the images, Tombaugh could identify celestial bodies that had shifted position against the background of fixed stars. On February 18, 1930, he successfully pinpointed the moving object that would be named Pluto.13