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|Annie Jump Cannon
once the world's foremost expert in stellar classifications
Annie Jump Cannon was born in Dover, Delaware, on December 11, 1863. Her interest in astronomy was first sparked by her mother, who taught her the constellations. After graduating from Wellesley College with a degree in physics in 1884, she returned to Delaware and played "dutiful daughter" for several years. She also developed an interest in the burgeoning field of photography, and in 1892 she embarked on a picture-taking tour of Europe. After she returned home she created a booklet of photos and prose from her trip, which was published in 1893 under the title In the Footsteps of Columbus.
After her mother's death in 1894, Annie returned to Wellesley as an assistant in the physics department and became a "special student" of astronomy at Radcliffe. In 1896, she was hired by Professor Edward Charles Pickering, director of the Harvard College Observatory, to catalog variable stars and classify the spectra of southern stars -- her career as an astronomer had officially begun. At this time there were actually several women on the payroll of the Observatory, almost all of whom were paid 50 cents an hour to record data, handle star classification, and/or perform complex data reduction.
Although astrophysics and stellar classification by spectra was relatively new, Cannon was a natural. Appointed curator of observational photographs at the Observatory in 1911, she began systematically examining photographic plates to classify all the stars down to the ninth magnitude -- some quarter of a million objects in all. She classified 5,000 stars per month between 1911 and 1915. She achieved this pace by organizing the work so that she would examine the plate and call out an alphabetical designation for each stellar spectrum to an assistant who would record it in a notebook set up for this purpose. In her record book she noted the date and time that she began and ended each classification session. Years later, if queried about the classification of any star, she could duplicate her original estimate to within a tenth of a category's subdivision. Although she had completed classifying the 225,300 stellar spectra by 1915, it took several more years to bring her work to publication. The stars had to be properly identified and the positions and magnitudes verified with other catalogs of the time. Therefore, the first volume of The Henry Draper Catalogue containing her work was not published until 1918, and the ninth volume was not published until 1924.
By now the world's foremost expert in stellar classifications, Cannon was still officially a temporary employee; she did not receive a permanent position at the Harvard College Observatory until 1938.
Annie Jump Cannon died in Cambridge, Massachusetts, on April 13, 1941.
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This page was last updated on 05/25/2017.