Annie Jump Cannon

Annie Jump Cannon
Credit: Royal Astronomical Society
care of Harvard College Observatory
Annie Jump Cannon (1863 –1941)

Annie Jump Cannon was born on December 11, 1863, in Dover, Delaware. Annie’s mother encouraged Annie’s interest in astronomy, teaching her the constellations and encouraging her to study physics and astronomy at Wellesley College, one of the top academic schools for women in the US. Annie graduated in 1884 with a degree in physics but went back home because there were few opportunities for women to work in science then. In 1892 Annie went to Europe to photograph the solar eclipse but two years later Annie’s mother died and Annie needed to find work.

Annie contacted Sarah Whiting, her teacher at Wellesley, who hired her as a junior physics teacher and encouraged her to take graduate courses in astronomy learning about spectroscopy and photography. So Annie enrolled at Radcliffe Women’s College at Harvard which gave her access to the Harvard College Observatory and in 1907, she finished her studies and got an M.A.

In 1896, Edward C. Pickering hired her as his assistant at the Harvard Observatory. “Pickering’s Women, as they were known, were hired to complete the Henry Draper Catalogue, mapping and classifying the stars. They examined the photographic plates, carried out astronomical calculations, catalogued the photographs and classified the stars by their spectra. They were poorly paid, getting just 25 cents an hour for seven hours a day, six days a week much less than the secretaries at Harvard were paid.

Not long after work began on the Draper Catalogue there was a disagreement about how to classify the stars. Annie came up with a compromise by basing the classification on the surface temperature of the stars and rearranging the letters of the original system to come up with the famous OBAFGKM classification which is still used today.

Annie’s career lasted for more than 40 years and she classified more stars in her lifetime than anyone else has ever achieved (about 350,000), she could classify three stars a minute just by looking at their spectral patterns. Her first catalogue of stellar spectra was published in 1901 and she also published catalogues of variable stars, including 300 that she had discovered herself.

Annie was the first person to get an honorary doctorate from Oxford and was the first woman elected as an officer of the American Astronomical Society. She became the Curator of Astronomical Photographs at Harvard and received the Henry Draper Medal (sharing it with a male colleague); only one other female has won this medal. There is now the Annie Cannon Prize, awarded to women astronomers who have made outstanding contributions in astronomy.