Edward Charles Pickering (director of the Harvard Observatory from 1877 to 1919) decided to hire women as skilled workers to process astronomical data. Among these women were Williamina Fleming, Annie Jump Cannon, Henrietta Swan Leavitt and Antonia Maury. This staff came to be known as the Harvard Computers.
The first woman hired was Williamina Fleming, who was working as a maid for Pickering. It seems that Pickering was increasingly frustrated with his male assistants and declared that even his maid could do a better job. Apparently he was not mistaken, as Fleming undertook her assigned chores efficiently. When the Harvard Observatory received in 1886 a generous donation from the widow of Henry Draper, Pickering decided to hire more female staff and put Fleming in charge.
As a result of the work of the women “computers”, Pickering published in 1890 the first Henry Draper Catalog, a catalog with more than 10,000 stars classified according to their spectrum. Pickering decided to hire Antonia Maury, a graduate from Vassar College, to reclassify some of the stars. Maury decided to go further and improved and redesigned the system of classification. It was published in 1897, but was largely ignored. Afterwards Pickering decided to hire Cannon, a graduate of Wellesley College, to classify the southern stars. As Maury had done, Cannon also ended up redesigning the classification system of the spectra and developed the Harvard Classification Scheme, which constitutes the basis of the system used today.
Henrietta Swan Leavitt’s insight that all the variable stars in the Small Magellanic Cloud are roughly the same distance from Earth, led to her discovering a direct relationship between the period of Cepheid variable stars and their intrinsic brightness. This discovery, in turn, led to the modern understanding of the true size of the universe, and Cepheid variables are still an essential tool for the measurement of cosmological distance.