Williamina Fleming

Lore & Background

Williamina Paton Stevens was born in Dundee, Scotland, in 1857, one of six children. She worked as a pupil-teacher from age fourteen. In 1877 she married James Orr Fleming, and they emigrated to Boston in 1878. After her husband abandoned her and their young son, she worked as a maid in the home of Professor Edward Charles Pickering, director of the Harvard College Observatory. In 1879, Pickering hired her for part-time administrative work, and by 1881 he formally invited her to join the observatory and taught her to analyze stellar spectra. She became one of the founding members of the Harvard Computers, an all-women team of human computers.

In 1886, the Henry Draper Memorial funded the observatory's work on the first Henry Draper Catalogue. Fleming was placed in charge of the project. She devised a system for classifying stars based on the amount of hydrogen in their spectra, known as the Pickering-Fleming system. The catalogue, published in 1890, contained more than 10,000 stars classified by spectrum, with Fleming doing the majority of the classifications. She also organized thousands of photographic plates for comparison. In 1898 she was appointed Curator of Astronomical Photographs at Harvard, the first woman to hold that position.

Fleming discovered 59 gaseous nebulae, over 310 variable stars, and 10 novae, including the Horsehead Nebula in 1888. She died of pneumonia in Boston on 21 May 1911.

Reader's Guide

Williamina Fleming's significance lies in her foundational work in stellar classification and her role as a pioneer for women in astronomy. At the Harvard College Observatory, she developed the Pickering-Fleming system for classifying stars by hydrogen abundance, which was later refined by Annie Jump Cannon into the Harvard spectral classification still used today. Her work on the Henry Draper Catalogue, which classified over 10,000 stars, provided a systematic basis for modern stellar astronomy. Fleming's discovery of the Horsehead Nebula and the first white dwarf star are notable achievements, though early credit for the nebula was sometimes omitted. She openly advocated for women in science, giving a talk at the 1893 World's Fair titled 'A Field for Woman's Work in Astronomy,' arguing that sex differences in achievement were culturally constructed. Her legacy includes the Fleming lunar crater, the asteroid 5747 Williamina, and ongoing efforts to preserve and digitize her notebooks through Project PHaEDRA at Harvard. She was the first American woman elected an honorary member of the Royal Astronomical Society of London in 1906.

Did You Know?

• Fleming discovered the Horsehead Nebula in 1888 on a plate made by astronomer W. H. Pickering.
• She was the first woman appointed Curator of Astronomical Photographs at Harvard College Observatory in 1898.
• Fleming's spectral classification of 40 Eridani B helped lay the groundwork for the later identification of the first white dwarf by Henry Norris Russell.
• She became a US citizen in 1907.