Williamina Fleming

Williamina Paton Stevens Fleming (15 May 1857 – 21 May 1911) was a Scottish astronomer. At the Harvard College Observatory, she contributed to the photographic classification of stellar spectra, helping to develop a common designation system for stars. Fleming cataloged more than ten thousand stars, 59 gaseous nebulae, over 310 variable stars, and 10 novae, among other astronomical phenomena. She is credited with the discovery of the Horsehead Nebula in 1888, and she was a vocal supporter of women's representation in her field.

Early life Williamina Paton Stevens was born in Dundee, Scotland, at 86 Nethergate, on 15 May 1857 to Mary Walker and Robert Stevens, a carver and gilder. She was one of six children. Her younger sister, Johanna Stevens, would also later work at Harvard College Observatory. Starting at the age of fourteen, she went to work as a pupil-teacher. In 1877, she married James Orr Fleming, an accountant and widower, also of Dundee. The couple had one son, Edward P. Fleming.

Career In 1878, aged 21, she and her husband emigrated to Boston, Massachusetts, US.

In 1881, Pickering formally invited Fleming to join the HCO and taught her how to analyze stellar spectra. She became one of the founding members of the Harvard Computers, an all-women cadre of human computers hired by Pickering to compute mathematical classifications and edit the observatory's publications.

The Harvard Computers, the group of women computers at the Harvard College Observatory, who worked for the astronomer Edward Charles Pickering. The group included Harvard computer and astronomer Henrietta Swan Leavitt, Annie Jump Cannon, Williamina Fleming, and Antonia Maury.

Henry Draper Catalogue, 1886 In 1886, Mary Anna Draper, the wealthy widow of astronomer Henry Draper, started the Henry Draper Memorial to fund the HCO's research. In response, the HCO began work on the first Henry Draper Catalogue, a long-term project to obtain the optical spectra of as many stars as possible and to index and classify stars by spectra.

Fleming was placed in charge of the Draper Catalogue project.

The latest Harvard College Observatory images contained photographed spectra of stars that extended into the ultraviolet range, which allowed much more accurate classifications than recording spectra by hand through an instrument at night. Stars showing hydrogen as the most abundant element were classified A; those of hydrogen as the second-most abundant element, B; and so on.

Later, her colleague Annie Jump Cannon reordered the classification system based on the surface temperature of stars, resulting in the Harvard spectral classification, which is still in use today.

In 1890, the HCO published the first Henry Draper Catalogue due to years of work by their female computer team, a catalog with more than 10,000 stars classified according to their spectrum. Fleming did the majority of these classifications. Fleming also made it possible to go back and compare recorded plates by organizing thousands of photographs by telescope along with other identifying factors.

Notable discoveries During her career, Fleming discovered a total of 59 gaseous nebulae, over 310 variable stars, and 10 novae.

In 1910, Fleming published her discovery of white dwarf stars.

She died of pneumonia in Boston on 21 May 1911, for her discovery of new stars Honorary fellow in astronomy of Wellesley College Commemorated on the Dundee Women's Trail

Legacy The Fleming lunar crater was jointly named after her and (not closely related) Alexander Fleming The asteroid 5747 Williamina is named after her. Kathryn Lasky published a book in 2021 about Fleming illustrated by Julianna Swaney called "She Caught the Light: Williamina Stevens Fleming: Astronomer" aimed at young people. In 2015, Lindsay Smith Zrull, curator of Harvard's Plate Stacks collection, was working to catalog and digitize the astronomical plates for Digital Access to a Sky Century @ Harvard (DASCH) and discovered about 118 boxes, each containing 20 to 30 notebooks, from women computers and early Harvard astronomers. Smith Zrull realized that the 2,500+ volumes were outside the scope of her work with DASCH but wanted to see the material preserved and made accessible. Smith Zrull contacted librarians at the Harvard–Smithsonian Center for Astrophysics. Daina Bouquin, Wolbach's Head Librarian, explained that the objective is to enable full-text search of the research: "If you search for Williamina Fleming, you're not going to just find a mention of her in a publication where she wasn't the author of her work. You're going to find her work."

In July 2017, the Wolbach Library at the Center for Astrophysics Harvard & Smithsonian unveiled a display showcasing Fleming's work, including the log book containing the Horsehead Nebula discovery.

, about 200 of over 2,500 volumes had been transcribed. The task is expected to take years to complete fully. Some of the notebooks are listed via the Smithsonian Digital Volunteers Web site, which encourages volunteers to transcribe them.