Founding of Harvard College Observatory

The Harvard College Observatory in Cambridge, Massachusetts, was established to carry out systematic astronomical observation at Harvard University, with William Cranch Bond as its first director. It became important in 1847 when the Great Refractor, then among the largest telescopes in the world, came into use. Under later directors, it pioneered astronomical photography and built an enormous collection of photographic plates of the sky. Women working as so-called computers, including Henrietta Swan Leavitt, who found the period-luminosity relation of Cepheid variable stars, and Annie Jump Cannon, who classified stars, made fundamental contributions. Cecilia Payne showed there that stars are made mainly of hydrogen and helium. Today it is part of the Harvard-Smithsonian Center for Astrophysics.

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