Elizabeth Williams and the Discovery of Pluto

In a presentation at MIT in 1902, Percival Lowell postulated the existence of a ninth planet and three years later began searching for what he called "Planet X". The search was twofold, involving mathematically calculating the position of the presumed planet and using telescopes at his observatory in Arizona to photograph likely areas of the sky as suggested by these calculations. He soon hired a young mathematician, Elizabeth Williams, to lead his team of "computers". Williams graduated from MIT in 1903, one of the top mathematics students in her class. When Lowell hired her in 1905, she worked out of his office in Boston. In carrying out the complex calculations necessary for the Planet X search, the talented Williams reportedly wrote in cursive with her right hand and printed with her left. Her calculations were critical to Lowell's predictions of the location of Planet X, as documented in his 1915 publication, Memoirs on a Trans-Neptunian Planet. Lowell died the following year and with him went the Planet X search. In the late 1920s, Lowell Observatory Sole Trustee Roger Putnam and Director VM Slipher decided to recommence the search, acquiring a specially designed astrograph for computing images and hiring 23-year-old farmer and amateur astronomer, Clyde Tombaugh. Looking in the area of sky where Lowell predicted Planet X would be located, Tombaugh discovered Pluto on February 18, 1930. As for Williams, she continued working at Lowell Observatory, moving from Boston to center of operation in Flagstaff in 1919. She married astronomer George Hamilton in 1922, at which time Lowell's widow, Constance, terminated their employment at Lowell. The couple moved to Harvard College Observatory's station in Mandeville, Jamaica and worked side-by-side there until his death in 1935. She then moved to New Hampshire, where she would eventually die penniless. Her name is now a footnote in history, but her efforts as an early astronomical computer stand as a testament to her brilliance and hard work.