Annie Jump Cannon: Astronomer

Written by Victoria Albitos

Edited by Lauren Fajardo


More than 150 years ago, a star was born; or rather, a girl who would grow up to watch the stars.

On December 11, 1863, Annie Jump Cannon was born in Dover, Delaware to Wilson Cannon, a shipbuilder and statesman, and his second wife Mary Jump. As a child, her mother taught her constellations and home economics. She also encouraged her to pursue studying mathematics and the sciences, all considered unusual career options for women at the time. She was an accomplished astronomer and also a suffragist.

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Annie Jump Cannon. Photo by the Smithsonian Institution on Flickr https://flic.kr/p/64CbRs

After graduating from Wellesley College in 1884 with a bachelor’s degree in physics, she returned home and spent nine years as a photographer, publishing a collection of her photographs. However, after contracting scarlet fever, which led to her almost total hearing loss, and the death of her mother, she decided to go back to Wellesley College in 1894 to teach physics and study advanced astronomy.

In 1896, she joined the Harvard Computers, a group of women working under Harvard Observatory director Edward C. Pickering, under whom she had studied astronomy since 1895. She worked alongside other women who would eventually be recognized as trailblazers of astronomy, including Williamina Fleming, Henrietta Leavitt, Antonia Maury, and Florence Cushman. Together they were nicknamed “Pickering’s Women” and worked on the Henry Draper Catalogue, a star catalogue named after the late Henry Draper, a wealthy physician and amateur astronomer. It was under a group of projects named the Henry Draper Memorial, funded by his widow, Mary Anna Draper, and contained classifications for 225,300 stars.

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The Harvard Computers at work. Photo from the Smithsonian Institution Archives

The Harvard Computers were paid between 25 to 50 cents an hour, in stark contrast to their male colleagues, who were paid twice that amount. As most of them, including Annie Jump Cannon, were unmarried, they were criticized for working instead of getting married and staying at home as housewives. Pickering also barred them from the “more important” duties in the observatory; they were only allowed to do clerical tasks, such as classifying stars and clearing up photographs. Nevertheless, they took the first steps out of the box in which society was trying to confine women, and contributed important work to the field of astronomy.

Annie Jump Cannon created the Harvard Classification Scheme, a universally adopted system that organizes stars based on their temperatures and spectral types. It was originally devised as a compromise between two systems her colleagues were pushing: a more complicated one made by Antonia Maury, and a simpler one made by Williamina Fleming. Maury made a scheme consisting of 22 groups, from I to XXII, with three subdivisions based on the sharpness of the stars’ spectral lines, a line that stood out from an otherwise uniform spectrum that was used to identify stars, a “fingerprint” of sorts. Fleming’s scheme was more straightforward, classifying stellar spectra according to their hydrogen spectral lines, in a sequence from A to Q.

Cannon simplified and reordered the systems, eventually ending up with the Harvard Classification Scheme, which was used in the nine-volume Henry Draper Catalogue (1918-1924). The system is still in use in modern astronomy today; the mnemonic, “Oh Be A Fine Girl Kiss Me”, standing for the seven spectral classes in the scheme, is still taught to astronomy students throughout the world. In 1922, the International Astronomical Union formally began using it as the official classification system for stars. That same year, Cannon moved to Arequipa, Peru, for six months to study and photograph the stars of the southern hemisphere.

During her career she found 300 variable stars, five novae, and one binary star system. She could classify three stars per minute and was known to be ruthlessly efficient. Her total record came up to around 350,000 manually classified stars. Pickering, her director, was in awe, stating that “Miss Cannon is the only person in the world—man or woman—who can do this work so quickly.”

In 1901, she published her first catalogue of stellar spectra. In 1911, she was made Harvard’s Curator of Astronomical Photographs, succeeding her colleague Williamina Fleming and becoming the second woman to hold the position. She was given the recognition and appreciation she deserved: in 1914, she was made an honorary member of the Royal Astronomical Society. In 1925, she received an honorary doctorate of science from Oxford—the first woman to do so. Ten years later, she created the Annie J. Cannon prize for women who made great contributions to astronomy. In 1938, she became Harvard’s William C. Bond Astronomer.

Annie Jump Cannon retired in 1940, after more than 40 years of work, but not before building a stellar legacy. She remained an active member of the observatory until the end of her life—literally. She continued to work in the observatory until a few weeks before her death. Today, the world honors her with a comet and a lunar crater carrying her name.

In life, she watched the stars. In death, she became one, a shining example for women in science.

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