Annie Jump Cannon

Annie Cannon (1863 -1941) became a member of Pickering’s women in 1896, the women hired by Harvard Observatory director to complete the Draper Catalogue mapping and defining all the stars in the sky to photographic magnitude of about 9.
Not long after the work on the Draper Catalogue began, a disagreement developed as to how to classify the stars. Cannon negotiated a compromise between a complex classification system and a more simple straightforward approach. She started by examining the bright southern hemisphere stars. To these stars she applied a third system, a division of stars into the spectral classes. Her scheme was based on the strength of the Balmer absorption lines. After absorption lines were understood in terms of stellar temperatures her initial classification system was rearranged to avoid having to update star catalogues.
Annie’s work was “theory laced” but simplified. How she could see the stars or stellar spectra was extraordinary. Her Henry Draper Catalogue listed nearly 230,000 stars and was valued as the work of a single observer. Annie also published many other catalogues of variable stars, including 300 that she discovered. Her career lasted more than 40 years, during which time women gained acceptance within the scientific community.
Annie Jump Cannon died April 13, 1941 after receiving a regular Harvard appointment as the William C. Bond Astronomer. She also received the Henry Draper Medal, which only one other woman has won.





