Williamina Fleming

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Williamina Paton Stevens Fleming
Black and white portrait photograph of Williamina Paton Stevens Fleming
Williamina Paton Stevens Fleming
Born(1857-05-15)15 May 1857
Dundee, Scotland
Died21 May 1911(1911-05-21) (aged 54)
Boston, Massachusetts, United States
Alma materNone
Scientific career

Williamina Paton Stevens Fleming (May 15, 1857 – May 21, 1911) was a Scottish astronomer. During her career, she helped develop a common designation system for stars and cataloged thousands of stars and other astronomical phenomena. Among several career achievements that advanced astronomy, Fleming is noted for her discovery of the Horsehead Nebula in 1888.[1]


Williamina Stevens was born in Dundee, Scotland on May 15, 1857, to Mary Walker and Robert Stevens, a carver and gilder.[2] There, in 1877, she married James Orr Fleming, an accountant and widower, also of Dundee. She worked as a teacher a short time before the couple emigrated to Boston, Massachusetts, US, when she was 21.[3]

Harvard College Observatory[edit]

After she and her child were abandoned by her husband, Williamina Fleming worked as a maid in the home of Professor Edward Charles Pickering, who was director of the Harvard College Observatory (HCO). The story was told that Pickering frequently became frustrated with the performance of the men working at the HCO and, reportedly, would complain loudly: "My Scottish maid could do better!"[4]

Pickering's wife Lizzie recommended Williamina as having talents beyond custodial and maternal arts, and in 1879 Pickering hired Fleming to conduct part-time administrative work at the observatory.[5] In 1881, Pickering invited Fleming to formally 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.[4] In 1886, Fleming was placed in charge of the group.[4]

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.

Pickering challenged Fleming to improve a preexisting classification of stars.[5] 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.[5] Fleming devised a system for classifying stars according to the relative amount of hydrogen observed in their spectra, known as the Pickering-Fleming system.[6] 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 upon the surface temperature of stars, resulting in the Harvard system for classifying stars that is still in use today.[7]

As a result of years of work by their female computer team, the HCO published the first Henry Draper Catalog in 1890, a catalog with more than 10,000 stars classified according to their spectrum. The majority of these classifications were done by Fleming.[8] Fleming also made it possible to go back and compare recorded plates, by organizing thousands of photographs by telescope along with other identifying factors.[5] In 1898, she was appointed Curator of Astronomical Photographs at Harvard, the first woman to hold the position.[6]

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

Most notably, in 1888, Fleming discovered the Horsehead Nebula on a telescope-photogrammetry plate made by astronomer W. H. Pickering, brother of E.C. Pickering. She described the bright nebula (later known as IC 434) as having "a semicircular indentation 5 minutes in diameter 30 minutes south of Zeta Orionis". Subsequent professional publications neglected to give credit to Fleming for the discovery. The first Dreyer Index Catalogue omitted Fleming's name from the list of contributors having then discovered sky objects at Harvard, attributing the entire work merely to "Pickering". However, by the time the second Dreyer Index Catalogue was published in 1908, Fleming and her female colleagues at the HCO were sufficiently well-known and received proper credit for their discoveries.

Fleming is also credited with the discovery of the first white dwarf:

The first person who knew of the existence of white dwarfs was Mrs. Fleming; the next two, an hour or two later, Professor E. C. Pickering and I. With characteristic generosity, Pickering had volunteered to have the spectra of the stars which I had observed for parallax looked up on the Harvard plates. All those of faint absolute magnitude turned out to be of class G or later. Moved with curiosity I asked him about the companion of 40 Eridani. Characteristically, again, he telephoned to Mrs. Fleming who reported within an hour or so, that it was of Class A.

— Henry Norris Russell "Astronomical Journal, Vol. 51, p. 13 (1944)".

Fleming published her discovery of white dwarf stars in 1910.[3] Her other notable publications include A Photographic Study of Variable Stars (1907), a list of 222 variable stars she had discovered; and Spectra and Photographic Magnitudes of Stars in Standard Regions (1911).

Fleming openly advocated for other women in the sciences in her talk "A Field for Woman's Work in Astronomy" at the 1893 World's Fair in Chicago, where she openly promoted the hiring of female assistants in astronomy. Her speech suggested she agreed with the prevailing idea that women were inferior, but felt that, if given greater opportunities, they would be able to become equals; in other words, the sex differences in this regard were more culturally constructed than biologically grounded.[9]

In 1906, she was made an honorary member of the Royal Astronomical Society of London, the first American woman to be so honored.[3] Soon after she was appointed honorary fellow in astronomy of Wellesley College. Shortly before her death the Astronomical Society of Mexico [es] awarded her the Guadalupe Almendaro medal for her discovery of new stars.

She died in Boston on May 21, 1911.[3]



The women of the Harvard Computers were famous during their lifetimes, but were largely forgotten in the following century. In 2015, Lindsay Smith Zrull, curator of Harvard's Plate Stacks collection, was working to catalog and digitize the astronomical plates for DASCH and discovered about 118 boxes, each containing 20 to 30 notebooks, from women computers and early Harvard astronomers. She 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 reached out to librarians at the Harvard-Smithsonian Center for Astrophysics.

In response, the Wolbach Library launched Project PHaEDRA (Preserving Harvard's Early Data and Research in Astronomy).[10] 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, Harvard-Smithsonian Center for Astrophysics's Wolbach Library unveiled a display showcasing Fleming's work,[11] including the log book containing the Horsehead Nebula discovery.[10] The library has dozens of volumes of Fleming's work in its PHaEDRA collection.[12]

As of August 2017, about 200 of over 2,500 volumes had been transcribed. The task is expected to take years to fully complete. Some of the notebooks are listed via the Smithsonian Digital Volunteers Web site, which encourages volunteers to transcribe them.[13]


  1. ^ Cannon, Annie J. (June 1911). "Williamina Paton Fleming". Science (published June 30, 1911). 33 (861): 987–988. Bibcode:1911Sci....33..987C. doi:10.1126/science.33.861.987. PMID 17799863.
  2. ^ Ewan, Elizabeth; Innes, Sue; Reynolds, Sian (2006). The biographical dictionary of Scottish women : from the earliest times to 2004. Edinburgh, Scotland: Edinburgh University Press. p. 121. ISBN 978-0748626601. OCLC 367680960. Retrieved 2019-02-14.
  3. ^ a b c d e "Women Working 1800–1930, Williamina Paton Stevens Fleming (1857–1911)". Harvard University Library Open Collections Program. Archived from the original on 2 April 2018. Retrieved 28 August 2017. With links to manuscripts and other resources.
  4. ^ a b c Smith, Lindsay (March 14, 2015). Williamina Paton Fleming. Project Continua. 1.
  5. ^ a b c d Sobel, Dava (2016). The Glass Universe. Viking. pp. xii. ISBN 978-0698148697.
  6. ^ a b "Williamina Paton Stevens Fleming". Encyclopaedia Britannica. Retrieved 19 February 2019.
  7. ^ Natasha Geiling (18 September 2013). "The Women Who Mapped the Universe And Still Couldn't Get Any Respect". Smithsonian Magazine. Retrieved 19 February 2019.
  8. ^ Harvard University. "About the Collection", Harvard.edu,[when?].
  9. ^ Rossiter, Margaret W. (1980). ""Women's Work" in Science, 1880–1910". Isis. 71 (3): 381–398. doi:10.1086/352540. JSTOR 230118.
  10. ^ a b Alex Newman (28 August 2017). "Unearthing the legacy of Harvard's female 'computers'". BBC News. Retrieved 28 August 2017.
  11. ^ Alex McGrath (3 July 2017). "The First Computer: Williamina Fleming and the Horsehead Nebula". Galactic Gazette. Retrieved 15 September 2017.
  12. ^ "Harvard College Observatory observations, logs, instrument readings, and calculations: an inventory". Harvard Library. Retrieved 28 August 2017.
  13. ^ "Harvard-Smithsonian Center for Astrophysics: Browse Projects". Smithsonian Digital Volunteers. Retrieved 28 August 2017.

Further reading[edit]

  • Sobel, Dava (2016). The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars. Penguin. ISBN 978-0670016952.
  • Shearer, Benjamin (1997). Notable women in the physical sciences : a biographical dictionary (1. publ. ed.). Westport, Conn. [u.a.]: Greenwood Press. ISBN 978-0313293030.

External links[edit]