The Farm Kid Who Found a Planet

On February 18, 1930, a 24-year-old lab assistant named Clyde Tombaugh sat at a blink comparator in Flagstaff, Arizona, and found Pluto. He was comparing two photographic plates of the same star field, taken six days apart, and noticed a tiny point of light that had shifted position. It wasn't a star. It was moving. After months of systematic searching, Tombaugh had found the ninth planet.

Tombaugh had been hired by Lowell Observatory in 1929 specifically to search for "Planet X," a hypothetical body beyond Neptune that Percival Lowell had predicted based on perceived gravitational perturbations. Tombaugh had no college degree. He was a Kansas farm kid who built his own telescopes from spare parts and sent drawings of Jupiter and Mars to the observatory. They hired him anyway. It was the best personnel decision in the history of planetary science.

enhanced color image of pluto taken by the new horizons spacecraft in 2015, revealing the dwarf planet's complex geology — mountains, plains, and the nitrogen ice heart that now bears tombaugh's name. source: wikimedia commons

The discovery was announced on March 13, 1930. The name "Pluto" was suggested by an eleven-year-old English girl, Venetia Burney, who thought the cold, distant world suited the Roman god of the underworld. It was adopted officially on May 1, 1930.

Pluto held its planetary status for 76 years until the International Astronomical Union reclassified it as a dwarf planet in 2006, a decision that still generates arguments. Tombaugh died in 1997, nine years before the demotion and eighteen years before NASA's New Horizons spacecraft flew past Pluto in 2015, revealing a geologically active world with heart-shaped plains now named Tombaugh Regio. The farm kid who found a planet got a continent named after him on its surface. That's a reasonable legacy.