On February 18, 1930, Pluto was officially discovered by astronomer Clyde W. Tombaugh at the Lowell Observatory in Flagstaff, Arizona. Tombaugh utilized an innovative astronomical technique that involved a combination of photographic plates and a blink microscope. Prior to this, the existence of an unknown ninth planet had been proposed by Percival Lowell, who theorized that the gravitational pull of this unknown body caused the disturbances observed in the orbits of Uranus and Neptune, though he was unable to find it during his lifetime.

The search for this elusive ninth planet began anew in 1929, leveraging the computations made by Lowell and W.H. Pickering. This led to a focused effort at the Lowell Observatory, culminating in the discovery made by Tombaugh on that fateful day in February 1930. This discovery sparked a significant interest and excitement in planetary science, as it broadened the understanding of our solar system and its composition, thereby changing how planets were categorized.

Pluto remained classified as the ninth planet until 2006 when its status was redefined by the International Astronomical Union, which reclassified it as a