Once the Solar System's Ninth Planet, Pluto Was Reclassified 20 Years Ago. Here's Why Planetary Scientists and the Public Alike Love the Small Icy Body

Clyde Tombaugh, a 24-year-old observatory assistant, discovered Pluto on February 18, 1930, at the Lowell Observatory in Flagstaff using a blink comparator to spot a moving dot among hundreds of thousands of stars on photographic plates—a discovery that fulfilled the late astronomer Percival Lowell's decades-long search for a hypothesized ninth planet and that was announced publicly on March 13, 1930, what would have been Lowell's 75th birthday.