Annie Cannon studies a plate

In 1896 Annie Jump Cannon was hired by Professor Edward Charles Pickering, director of the Harvard College Observatory, to catalogue variable stars and classify the spectra of southern stars. There were many women on staff there. They were referred to as “computers” because they handled star classification and complex data reduction. They were paid 50 cents an hour! The other women who worked there as assistants were referred to as “recorders” because they recorded the data. The following image of Pickering and the women on staff was taken on May 13, 1913 in front of the newest and largest building where most of the women worked.

Staff at Harvard College Observatory, 1913

The next image is from 1918. The women at the Harvard Observatory are posed like paper dolls, along with Frank Hinkely and Professor Edward King.

Staff at Harvard College Observatory, 1918

From left to right: Ida Woods (Wellesley 1893), Evelyn Leland, Florence Cushman, Grace Brooks, Mary Van, Henrietta Leavitt, Mollie O'Reilly, Mabel Gill, Alta Carpenter, Annie Jump Cannon (Wellesley 1884), Dorothy Black, Arville Walker, Frank Hinkely, and Professor Edward King.

Although astrophysics and stellar classification by spectra was relatively new, Annie was a natural. In the article “Annie Jump Cannon: Classifier of the Stars” which appeared in the Wellesley Magazine, Barbara Welther writes about Annie's great talent:

Miss Cannon's keep visual memory as well as her patience and discipline particularly qualified her to sort out these line patterns and to place each star in its proper category. Therefore, when Miss Cannon was appointed curator of observational photographs at the observatory in 1911, she began systematically examining these photographic plates to classify all the stars down to the ninth magnitude — some quarter of a million objects in all. The speed with which Miss Cannon worked was phenomenal. She classified 5,000 stars per month between 1911 and 1915. To keep such a pace she organized the work so that she would examine the photographic 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. For sparsely populated regions of the sky, Miss Cannon achieved a rate of more than 3 stars a minute. For denser regions her rate was halved. In her record book she noted the date and time that she began and ended each classification session. Although she was modest about her remarkable talent, she obviously took a deep inner pride in performing efficiently and effectively. 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 catalogues of the time. Therefore the first volume of The Henry Draper Catalogue containing her work was not published until 1918, and the ninth volume finally became available in 1924.

Annie's hard work earned her a number of academic honors and several prizes. The American Association of University Women annually present the Annie Jump Cannon Award to a woman beginning in the field of astronomy. In 1923 she was voted one of the 12 greatest living women in America. She was also presented the Draper Award by the National Academy of Sciences. During the award ceremony Harlow Shapley, the presenter said:

The benign presence of the Brick Building, noted collector of degrees and medals, author of nine immortal volumes, and several thousand oatmeal cookies, Virginia reeler, bridge player, and, especially the recipient of the Draper Medal of the National Academy of Science — the first medal ever bestowed on a woman by the honorable body of fossils and one of the highest honors attainable by astronomers of any sex, race, religion, or political preference.

Finally in 1938 she received a permanent position at the Harvard College Observatory.

Annie Cannon became the world's expert in stellar classification, as well as developing and fine-tuning the Harvard system of classification that is studied by astronomy students today. Annie loved her career. Months before her death in 1941 in a letter to one of her classmates (now in the Wellesley Archives) she wrote:

At the Observatory, I am classifying, classifying and now getting ready to start on a large piece for Yale Observatory. It will be a job! And will keep several assistants busy doing minor details. Of course I love to do it.