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Annie Jump Cannon: Celestial Computer

Annie Jump Cannon was the eldest child of Wilson Lee Cannon, a successful ship-builder and state senator, and Mary Elizabeth, his second wife. She was born in Dover, Delaware on December 11, 1863 and as a young girl became enthralled with astronomy from excursions with her mother who taught her the constellations. Cannon graduated from Wellesley College in 1884 where she studied physics and astronomy with famed professor Sara Whiting.

For the next eleven years, Cannon studied music and traveled. It was during this time, after a bout of scarlet fever, that she lost her hearing. Upon the death of her mother, she decided to pursue her interests in astronomy and went to Radcliffe College as a “special student” for two years. Edwin Pickering was instrumental in her obtaining this special status. In 1896, she joined the ranks of computers at Harvard College Observatory.

Cannon’s duties included cataloguing variable stars and classifying the spectra of stars in the southern hemisphere for the Henry Draper Catalogue project, the counterpart to Maury with the northern hemisphere. In her free time, Cannon poured over the observatory’s photographic plate collection, studying variable stars.

Possibly due to her deafness, Cannon was “recognized even during her lifetime as the world’s expert in identifying and classifying stars, with incredible accuracy and speed.” By the time of her death, she had classified up to 350,000 stars, at a rate of up to 300 per hour.

Cannon refined the cataloguing schemes of her predecessors, Fleming and Maury. With Fleming’s scheme, she reduced the categories to seven and arranged them by temperature, from high to low, leaving OBAFGKM. With Maury’s system, instead of lower-case letters, Cannon used numbers from 1-10 to reflect gradation within each category. Her category scheme was so “user-friendly,” it was officially adopted as the standard in 1910 by the International Astronomical Union. Today, with minor changes, Cannon’s system is known as the Harvard Spectral Classification.

Cannon worked at Harvard College Observatory for 45 years, until her death at age 77 from heart failure and arteriosclerosis on April 13, 1941. During that time, Cannon took over the duties as Curator of Astronomical Photographs when Fleming died in 1911. Cannon also published several volumes of catalogues, including her “Provisional Catalogue” in 1903, with a revision in 1907 listing 1,957 variable stars and their discoverers, the most complete list of its kind at the time. She also revised the Henry Draper Catalogue down to 8th magnitude, published in sections between 1918 and 1924.

Cannon was recognized by her peers for her contributions to astronomy. She received six honorary degrees, one from Oxford University, the first given to a woman, and was the first woman to receive the Draper Gold Medal. With the money she received from one award, the Ellen Richards Research Prize of the Association to Aid Scientific Research by Women, Cannon established an award to recognize contributions to astronomy by women.

Annie Jump Cannon: Theorist of Star Spectra

Annie Jump Cannon, 4000 Years of Women in Science

Annie Jump Cannon, Wellesley University

Back to The Harvard Computers: From Pickering's Harem to Astronomy's Stars.

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Updated 20.10.2022
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