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Williamina Fleming

Williamina Fleming

The first of the famous women astronomers at the Harvard College Observatory, Williamina Fleming (1857-1911) helped to revolutionize astronomy in the late nineteenth and early twentieth centuries. She discovered ten novae, or exploding stars, and more than 200 variable stars. She also developed a new star classification system. Fleming was considered to be the leading female astronomer of her day and her achievements opened up the field of astronomy for women.

Born in Dundee Scotland on May 15, 1857, Williamina (known as Mina) Fleming was the daughter of Robert and Mary (Walker) Stevens. Her father had a profitable carving and gilding business and was well known for his picture frames. He was also one of the first in Dundee to experiment with photography. He died when his daughter was seven. Fleming attended public schools in Dundee until she was 14. She then worked as a student teacher until she married James Orr Fleming at the age of 20. In 1878, the couple emigrated to the United States, settling in Boston, Massachusetts. Soon after their arrival, her husband deserted her. To make matters worse, she was pregnant. Fleming was forced to work as a maid to support herself. Her choice of employers would change her life

From Housekeeper to Astronomer

In 1879 Fleming went to work for Edward C. Pickering, an astrophysicist and the new director of the Harvard College Observatory. She returned briefly to Scotland that fall to give birth to her son. Presumably, she wanted to be with her family for the birth. Pickering must have made a great impression on her in the brief time they knew one another, because she named her son Edward Pickering Fleming. Pickering was an advocate of higher education for women and an exacting employer. Frustrated with the inefficiencies of his male assistant, the story goes that he proclaimed that even his Scottish maid could do a better job and he set out to prove it. Soon, the 24-year-old Fleming had progressed from housework to astronomical observations.

The major work of the Harvard Observatory, made possible by the Draper Memorial established by Mary Anna Palmer Draper in 1886, was to use photographs to analyze the spectra, brightness, positions, and motions of stars. Photographs revealed wavelengths of light that were invisible to the human eye and therefore had never been seen with telescopes. The photographs of star spectra, the pattern of bands and lines that form when a star's light is dispersed through a prism, provided an entirely new way of classifying and analyzing stars. Nettie A. Farrar, an assistant at the Observatory who was leaving to marry, trained Fleming to analyze the spectra. Fleming's most important contribution to astronomy was her classification of 10,351 stars into 17 categories for the Draper Catalogue of Stellar Spectra, published in 1890. Her system of classification, known as the Pickering-Fleming System, supplanted the original classification system devised by Pickering.

In the course of her career, Fleming examined nearly 200,000 photographic plates, made at Cambridge and at Harvard's southern observatory in Arequipa, Peru, and supervised their classification. Fleming's studies of these photographic plates of star spectra led to her discoveries of ten of the 24 novae that were known at the time of her death in 1911. Novae are stars whose light suddenly increases dramatically and then fades. She also discovered 59 gaseous nebulae. Gaseous nebulae are high density interstellar dust or clouds, belonging to two groups of nebulae—planetary and diffuse. One of her most important discoveries concerned long-period variable stars, which were thought to be very rare, since their brightness changed so slowly that the magnitude of brightness was not observed to vary. Fleming discovered that variable stars could be identified by certain spectral characteristics. This enabled her to identify and analyze 222 of these of stars. Furthermore, she selected comparison stars that enabled the brightness of the variable stars to be determined with accuracy. This was the first photographic standard for determining the magnitude of star brightness. Of the 107 unusual Wolf-Rayet stars known at the time, Fleming discovered 94. In 1891, Fleming discovered spectral variations corresponding to changes in the light from the star Beta Lyrae, indicating that it was a double star. The latter discovery is usually credited to Pickering. Fleming's early work was published under Pickering's name, although by 1890, "M. Fleming" was appearing on the reports as Pickering's coauthor.

Directed the Women of the Harvard College Observatory

Fleming's work at the observatory was so outstanding that Pickering put her in charge of hiring and supervising a team of women to sort and study the immense collection of photographs of star spectra. Over the next 15 years, Fleming hired some 20 women. Some of them were college graduates who had majored in astronomy and went on to become famous astronomers in their own right. Among these women were Antonia Maury, Henrietta Leavitt, and Annie Jump Cannon. In 1893, Fleming gave a speech on women's work in astronomy at the Chicago World's Fair, and following this, astronomy as a scientific profession for women became a subject for the popular press. As a result, other observatories around the United States began hiring women.

In 1898, Fleming was made curator of astronomical photographs at the Observatory, the first woman appointed by the Harvard Corporation. She directed the work of the other women, assisted Pickering at the Observatory, and prepared the work of other astronomers for publication. Much of her time was occupied with editing the Annals of the Harvard College Observatory, which she resented because this distracted her from her own astronomical research. Fleming worked 60-hour weeks for a salary of $1,500 per year, which was far below what the newest male assistant at the Observatory received. Her recently discovered journals from 1900 reveal her frustration with this situation, particularly because she was putting her son through the Massachusetts Institute of Technology at the time. She had to struggle to make ends meet, but she was even more indignant at having her work and expertise undervalued.

Fleming was awarded honorary memberships in the Royal Astronomical Society and the French and Mexican astronomical societies. The latter presented her with a gold medal for her discovery of new stars. She was one of 11 women charter members of the American Astronomical Society and an honorary fellow of Wellesley College. After her death from pneumonia at the age of 54, Fleming was succeeded as curator by her protege, Annie Jump Cannon.


Jones, Bessie Z. and Lyle Boyd. The Harvard College Observatory: The First Four Directorships, 1839-1919. Harvard University Press, 1971.

Notable American Women 1607-1950: A Biographical Dictionary. Edited by Edward T. James, Janet Wilson James, and Paul W. Boyer. Harvard University Press, 1971.

Rossiter, Margaret W. Women Scientists in America: Struggles and Strategies to 1940. Johns Hopkins University Press, 1982.


Science, June 30, 1911. □

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Fleming, Williamina Paton

Fleming, Williamina Paton

(b. Dundee, Scotland, 15 May 1857; d. Boston, Massachusetts, 21 May 1911)


Mrs. Fleming’s father, Robert Stevens, a craftsman whose shop sold picture frames, died when she was seven; her mother was Mary Walker Stevens. After a public school education in Dundee, she married James Orr Fleming on 26 May 1877, and they immigrated to Boston at the end of 1878. Shortly thereafter the marriage fell apart, and Mrs. Fleming found it necessary to support herself and her infant son, Edward Pickering Fleming, who was born 6 October 1879. In 1881, after a period of domestic work for Edward C. Pickering, the new director of the Harvard College Observatory, she became a fulltime copyist and computer at the observatory itself.

At that time Pickering had just embarked on an extensive program of celestial photography. Through her studies of the objective prism spectrum plates, usually in collaboration with Pickering, Mrs. Fleming became the leading woman astronomer of her day. Her suspicions aroused by the spectral peculiarities she observed, she discovered more than 200 variable stars and ten novae—the latter being a significant fraction of the twenty-eight novae recorded up to the time of her death.

Her most important contribution was the classification of 10,351 stars in the Draper Catalogue of Stellar Spectra (published as volume XXVII of the Annals of Harvard College Observatory [1890]). The spectra were organized into seventeen categories, lettered from A to Q, but 99.3 percent of the stars fell in the six classes A, B, F, G, K, and M. Although it was a great advance over the four types into which Angelo Secchi had visually classified about 4,000 stellar spectra, Mrs. Fleming’s system was soon to be enormously refined at Harvard by Annie Jump Cannon.

Mrs. Fleming’s keen eyesight, remarkable memory, and industrious nature enabled her to advance to a position of considerable authority at the observatory, so that ultimately she gave assignments to a corps of a dozen women computers. In 1899 she was appointed curator of astronomical photographs, and by 1910 she had examined nearly 200,000 plates. In 1906 she became the fifth woman member (honorary) of the Royal Astronomical Society. Dorrit Hoffleit has written, “Sparkling and friendly though she was, her reputation as a strict disciplinarian lived after her, and as late as the 1930’s elderly ladies who had worked with her in their youth still regarded her with awe.”


Mrs. Fleming’s principal work appeared in the Annals of Harvard College Observatory, including an important paper, “Stars Having Peculiar Spectra,” published posthumously in vol. 56 (1912).

Most published biographical material derives from the obituaries by Annie Jump Cannon, in Astrophysical Journal, 34 (1911), 314–317; Edward C. Pickering, privately printed (1911), repr. in Harvard Graduates Magazine, 20 (1911), 49–51; or from the sketch by Grace A. Thompson, in New England Magazine, 48 (1912), 458–467

The best biography, incorporating some new material, is Dorrit Hoffleit, in Notable American Women (Cambridge, Mass., 1971).

Owen Gingerich

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