A 24-year-old farm boy with no degree found a new planet

Clyde Tombaugh had never finished college when the Lowell Observatory hired him in 1929 to hunt for a hypothetical 'Planet X'. Comparing photographic plates of the night sky night after night with a blink comparator, he spotted a faint dot that had moved — Pluto — in February 1930. He was 24 years old and self-taught in astronomy.

— Wikipedia contributors, Clyde Tombaugh — Discovery of Pluto, 1930