Is Pluto A Planet? How Clyde Tombaugh Discovered Pluto In 1930

By | February 16, 2021

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Clyde W. Tombaugh, discoverer of the planet Pluto. (Getty Images)

On February 18, 1930, a young, eager, self-taught astronomer named Clyde Tombaugh made an observation that changed the way we think about our galaxy as well as the trajectory of his own life. Who was Clyde Tombaugh? How did he discover Pluto? Is Pluto even a planet?

Clyde Tombaugh

Clyde Tombaugh was born on February 4, 1906 in Streator, Illinois. He was the son of impoverished farmers Muron Dealvo Tombaugh and Adella Pearl Chritton Tombaugh, who moved to Burdett, Kansas when young Clyde was 16 years old. After graduating from the local high school, the space enthusiast planned to study astronomy in college, but his dreams were derailed when a violent hailstorm destroyed the family's crops, pushing them to the edge of bankruptcy.

Although Tombaugh was devastated by the financial and academic setback, he was determined to continue his independent study of the planets and stars. In 1926, Tombaugh began constructing a series of homemade telescopes with powerful lenses and mirrors, which he learned how to do from an article in Popular Astronomy. With just a shovel in hand, he dug a large trench in his backyard to create an environment with a constant temperature and no wind, ensuring the most accurate images, although his family used it as a root cellar and tornado shelter. He even taught himself complex geometry and trigonometry to analyze his observations.

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Tombaugh at his family's farm with his homemade telescope, 1928. (Unknown author/Wikimedia Commons)

Planet X

He sent his drawings and reports to the Lowell Observatory in Flagstaff, Arizona for advice from its scientists, intriguing the observatory's owner, Percival Lowell, who invited the 23-year-old Tombaugh to work for him. Lowell was an eccentric businessman who built the observatory largely to prove his suspicion that Mars contained artificial irrigation canals, but by the time Tombaugh entered his life, he had moved on to a new pet theory: a potential ninth planet orbiting the Sun beyond Neptune. He wasn't alone—astronomers of the day called the theoretical celestial body Planet X.

At Lowell Observatory, Tombaugh fulfilled his employer's wish of identifying this planet, though probably not in as flashy a manner as he'd hoped. Tombaugh simply compared two photographs of the same star field, taken six days apart, and noted that while the stars all remained constant, one tiny, dim object at the far edge of the galaxy—now known as Pluto—appeared to have moved.