Elizabeth Langdon Williams

Born on 8 February 1879 in Putnam, Connecticut, Elizabeth Langdon Williams was an astronomer whose mathematical calculations helped lead to the discovery of Pluto. Williams studied physics at MIT, where she was one of the first women graduates, earning her degree with distinction in 1903. In 1905 she was hired by Percival Lowell to work in his Boston office as a human computer , carrying out calculations on the vast amount of astronomical data being collected. By 1915 she had become the head of Lowell’s computer team. Her calculations of the orbit of a suspected ninth planet, Lowell’s so-called Planet X, led to a survey of the ecliptic and the first captured image of Pluto in 1915, although no one realized it at the time. Lowell died the following year, but Williams continued her work. In 1930 Clyde Tombaugh, working at the Lowell Observatory in Arizona, discovered Pluto. (The discovery was made despite Lowell’s incorrect assumption that Planet X significantly impacted the orbits of Uranus and Neptune.) Williams died in 1981. (Photo credit: Lowell Observatory Archives)

Date in History: 8 February 1879