A Year: Day to Day Men; 11th of December

Handstand at Window

December 11 was the birthdate of American astronomer Annie Jump Cannon. 

Born in Dover, Delaware to Wilson Cannon, a shipbuilder, and Mary Jump, Annie Jump Cannon was encouraged by her mother to follow her own interests and suggested studies in chemistry, biology and mathematics at Wellesley College in Massachusetts. Taught by her mother to identify stars at an early age, Cannon decided to pursue her love of astronomy. She also made the choice not to marry or bear children. 

In 1880, Annie Cannon attended Wellesley College, one of the top academic schools for women, where she studied under Sarah Francis Whiting, one of the few women physicists in the United States at that time. Cannon graduated as the valedictorian of the college in 1884 with a degree in physics. She returned for a decade to Delaware where she developed skills in the new art of photography. Cannon traveled through Europe in 1892 taking photographs, later published along with her prose in a pamphlet, “In the Footsteps of Columbus”. This pamphlet was later used as a souvenir for the 1893 World’s Columbian Exposition in Chicago. 

Stricken with scarlet fever, Cannon became nearly deaf and immersed her self in her work. She became a junior physics teacher at Wellesley College in 1894 and took graduate courses in both physics and astronomy. In order to gain access to a more powerful telescope, Cannon enrolled at Radcliffe College as a special student; she was able to attend lectures by Harvard professors and gained access to the Harvard College Observatory. In 1896 Cannon was hired as an assistant to the observatory’s astronomer and physicist Edward C. Pickering. In 1907, she graduated with her Masters Degree from Wellesley in 1907. 

In 1896, Annine Cannon became a member of Pickering’s Harvard Computers, a group whose goal was to complete the Henry Draper Catalogue, a mapping and definition of every star in the sky to a photographic magnitude of nine. When Cannon first started cataloging stars, she was able to classify one- thousand stars in three years. By 1013, she was able to accurately classify two-hundred stars an hour by looking at their spectral patterns. 

Cannon is credited with the creation of the Harvard Classification Scheme, the first serious attempt to organize and classify stars based on their temperature and spectral types. She initially started by examining stars in the southern hemisphere and divided them into the spectral classes O, B, A, F, G, K, M based on the Balmer absorption lines that describe the spectral line emissions of the hydrogen atom. After this was understood, her initial classification system was rearranged to avoid updating previous star catalogues. 

In 1911, Annie Jump Cannon was made Curator of Astronomical Photographs at Harvard. Three years later, she became an honorary member of England’s Royal Astronomical Society. In 1922, the International Astronomical Society adopted Cannon’s classification system; except for a few minor changes, it is the basis of star classification to this date. Throughout her forty year career, Cannon manually classified more stars in a lifetime then anyone else, a total of approximately three-hundred and fifty thousand stars.