Henrietta Leavitt, Cecilia Payne Gaposchkin and the women of Harvard Observatory

In the late 19th and early 20th centuries the Harvard College Observatory provided unusual employment opportunities for a large number of women. At first their job title was computer or assistant, but in time several graduated to astronomer and made important contributions to the field. Henrietta Leavitt, for example, noticed the relation of periodicity to brightness among Cepheid variable stars that became the basis for interstellar and intergalactic distance scales. Cecilia Payne (later Gaposchkin) took advantage of a fellowship to leave Cambridge, England for Cambridge, Massachusetts, where she became the first person to earn a doctorate in astronomy from Harvard University. Her dissertation gave the first indication that stars consist primarily of hydrogen.