Williamina Fleming

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Williamina Paton Stevens Fleming
Williamina Paton Stevens Fleming circa 1890s.jpg
Williamina Paton Stevens Fleming
Born(1857-05-15)May 15, 1857
Dundee, Scotland
DiedMay 21, 1911(1911-05-21) (aged 54)
Boston, Massachusetts, United States
Alma materNone
Scientific career
Fields Astronomy

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]

Scottish people ethnic inhabitants of Scotland

The Scottish people or Scots, are a nation and Celtic ethnic group native to Scotland. Historically, they emerged from an amalgamation of two Celtic-speaking peoples, the Picts and Gaels, who founded the Kingdom of Scotland in the 9th century. Later, the neighbouring Celtic-speaking Cumbrians, as well as Germanic-speaking Anglo-Saxons and Norse, were incorporated into the Scottish nation.

Horsehead Nebula dark nebula in the constellation Orion

The Horsehead Nebula is a small dark nebula in the constellation Orion. The nebula is located just to the south of Alnitak, the easternmost star of Orion's Belt, and is part of the much larger Orion Molecular Cloud Complex. It appears within the southern region of the dense dust cloud known as Lynds 1630, along the edge of the much larger HII nebula region called IC 434.



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]

Dundee City and council area

Dundee is Scotland's fourth-largest city and the 51st-most-populous built-up area in the United Kingdom. The mid-year population estimate for 2016 was 148,270, giving Dundee a population density of 2,478/km2 or 6,420/sq mi, the second-highest in Scotland. It lies within the eastern central Lowlands on the north bank of the Firth of Tay, which feeds into the North Sea. Under the name of Dundee City, it forms one of the 32 council areas used for local government in Scotland.

Harvard College Observatory

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]

Edward Charles Pickering American astronomer

Edward Charles Pickering ForMemRS HFRSE was an American astronomer and physicist and the older brother of William Henry Pickering. Along with Carl Vogel, Pickering discovered the first spectroscopic binary stars. He wrote Elements of Physical Manipulations.

Harvard College Observatory observatory

The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, USA, and was founded in 1839. With the Smithsonian Astrophysical Observatory, it forms part of the Harvard–Smithsonian Center for Astrophysics.

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]

Harvard Computers group of humans

The Harvard Observatory, under the direction of Edward Charles Pickering and, following his death in 1919, Annie Jump Cannon had a number of women working as skilled workers to process astronomical data. "The women were challenged to make sense of these patterns by devising a scheme for sorting the stars into categories. Annie Jump Cannon’s success at this activity made her famous in her own lifetime, and she produced a stellar classification system that is still in use today. Antonia Maury discerned in the spectra a way to assess the relative sizes of stars, and Henrietta Leavitt showed how the cyclic changes of certain variable stars could serve as distance markers in space." Among these women were Williamina Fleming, Annie Jump Cannon, Henrietta Swan Leavitt, Florence Cushman and Antonia Maury. Although these women started primarily as calculators, they often rose to contribute to the astronomical field, and even publish in their own names. This staff came to be known as the Harvard Computers.

Human computer occupation

The term "computer", in use from the early 17th century, meant "one who computes": a person performing mathematical calculations, before electronic computers became commercially available. "The human computer is supposed to be following fixed rules; he has no authority to deviate from them in any detail." Teams of people were frequently used to undertake long and often tedious calculations; the work was divided so that this could be done in parallel. Frequently, the same calculations were performed independently by separate teams to check the correctness of the results.

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. Astronomer Edward Charles Pickering's Harvard computers.jpg
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]

Star An astronomical object consisting of a luminous spheroid of plasma held together by its own gravity

A star is an astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the estimated 300 sextillion (3×1023) stars in the Universe are invisible to the naked eye from Earth, including all stars outside our galaxy, the Milky Way.

Hydrogen Chemical element with atomic number 1

Hydrogen is a chemical element with symbol H and atomic number 1. With a standard atomic weight of 1.008, hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass. Non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed protium, has one proton and no neutrons.

Spectrum Continuous range of values, such as wavelengths in physics

A spectrum is a condition that is not limited to a specific set of values but can vary, without steps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors in visible light after passing through a prism. As scientific understanding of light advanced, it came to apply to the entire electromagnetic spectrum.

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]

Related Research Articles

The Henry Draper Catalogue (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars. In all, 359,083 stars were classified as of August 2017.

Annie Jump Cannon American astronomer

Annie Jump Cannon was an American astronomer whose cataloging work was instrumental in the development of contemporary stellar classification. With Edward C. Pickering, she is credited with the creation of the Harvard Classification Scheme, which was the first serious attempt to organize and classify stars based on their temperatures and spectral types. She was nearly deaf throughout her career. She was a suffragist and a member of the National Women's Party.

Helen Sawyer Hogg 20th-century astronomer

Helen Battles Sawyer Hogg, CC was an astronomer noted for pioneering research into globular clusters and variable stars. She was the first female president of several astronomical organizations and a notable woman of science in a time when many universities would not award scientific degrees to women. Her scientific advocacy and journalism included astronomy columns in the Toronto Star and the Journal of the Royal Astronomical Society of Canada. She was considered a "great scientist and a gracious person" over a career of sixty years.

Harlow Shapley American astronomer

Harlow Shapley was an American scientist, head of the Harvard College Observatory (1921–1952), and political activist during the latter New Deal and Fair Deal.

Astrophysics is the branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the astronomical objects, rather than their positions or motions in space". Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background. Emissions from these objects are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists apply concepts and methods from many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

Cecilia Payne-Gaposchkin American astronomer

Cecilia Helena Payne-Gaposchkin was a British-born American astronomer and astrophysicist who proposed in her 1925 doctoral thesis that stars were composed primarily of hydrogen and helium. Her groundbreaking conclusion was initially rejected because it contradicted the scientific wisdom of the time, which held that there were no significant elemental differences between the Sun and Earth. Independent observations eventually proved she was correct.

Henrietta Swan Leavitt American astronomer

Henrietta Swan Leavitt was an American astronomer. A graduate of Radcliffe College, she worked at the Harvard College Observatory as a "computer", tasked with examining photographic plates in order to measure and catalog the brightness of stars. This work led her to discover the relation between the luminosity and the period of Cepheid variables. Though she received little recognition in her lifetime, Leavitt's discovery provided astronomers with the first "standard candle" with which to measure the distance to faraway galaxies. After her death, Edwin Hubble used Leavitt's luminosity–period relation, together with the galactic spectral shifts first measured by Vesto Slipher at Lowell Observatory, in order to establish that the universe is expanding.

Antonia Maury astronomer

Antonia Maury was an American astronomer who published an important early catalog of stellar spectra. Maury was part of the Harvard Computers, a group of female astronomers and Human Computers at the Harvard College Observatory. Winner of the Annie Jump Cannon Award in Astronomy in 1943.

Margaret Geller American astronomer

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Florence Cushman (1860-1940) was an American astronomer at the Harvard College Observatory who worked on the Henry Draper Catalogue.

Anna Winlock (1857-1904) was an American astronomer and human computer, one of the first members of female computer group known as "the Harvard Computers." She made the most complete catalog of stars near the north and south poles of her era. She is also remembered for her calculations and studies of asteroids. In particular, she did calculations on 433 Eros and 475 Ocllo.

TZ Cassiopeiae star

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Adelaide Ames was an American astronomer and research assistant at Harvard University. She contributed to the study of galaxies with her co-authorship of A Survey of the External Galaxies Brighter Than the Thirteenth Magnitude, which was later known as the Shapley-Ames catalog. Ames was a member of the American Astronomical Society. She was a contemporary of Cecilia Payne-Gaposchkin and her closest friend at the observatory.

Mary Anna Draper American astronomer known for her work with astronomical photography

Mary Anna Draper, also known as Mary Anna Palmer Draper, was an American, known for her work with her husband, Henry Draper, with astronomical photography and research. She helped found the Mount Wilson Observatory and created an award for astronomical research, the Henry Draper Medal of the National Academy of Sciences.

Evelyn Leland was an American astronomer and "Harvard computer", one of the women who worked at the Harvard College Observatory with Edward Pickering. She worked there from 1889 to 1925. She studied stellar spectra extensively, discovered variable stars, and published papers with others from the observatory.

Sidney Carne Wolff is an American astrophysicist, researcher, public educator, and author. She is the first woman in the United States to head a major observatory, and she provided significant contributions to the construction of six telescopes. Wolff served as Director of the Kitt Peak National Observatory (KPNO) and the National Optical Astronomy Observatory (NOAO). She is a member of the International Astronomical Union's Division G: Stars and Stellar Physics.


  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. 1 2 3 4 5 "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. 1 2 3 Smith, Lindsay (March 14, 2015). Williamina Paton Fleming. Project Continua. 1.
  5. 1 2 3 4 Sobel, Dava (2016). The Glass Universe. Viking. pp. xii. ISBN   978-0698148697.
  6. 1 2 "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. JSTOR   230118.
  10. 1 2 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