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.