The Harvard Computers were multiple generations of women working as skilled workers and astronomers to process astronomical data primarily from photographic plates at the Harvard College Observatory in Cambridge, Massachusetts, United States. Created during the tenure of Edward Charles Pickering and, first headed by Williamina Fleming then Annie Jump Cannon.The women were challenged to make sense of these patterns by devising a scheme for sorting the stars into categories. Annie Jump Cannon's success at this activity made her famous in her own lifetime, and she produced a stellar classification system that is still in use today. Antonia Maury discerned in the spectra a way to assess the relative sizes of stars, and Henrietta Leavitt showed how the cyclic changes of certain variable stars could serve as distance markers in space.