Annie Jump Cannon

From Academic Kids

Annie Jump Cannon ( December 11, 1863April 13, 1941), US astronomer.

She was born to shipbuilder and state senator, Wilson Lee Cannon, and his second wife, Mary Elizabeth Jump, in Dover, Delaware. Mary gave birth to two more daughters after Annie, in addition to the four step children she inherited in the marriage. Annie's mother had a childhood interest in star gazing, and she passed that interest along to Annie.



At Wilmington Conference Academy, Annie showed promise as a student, particularly in mathematics. In 1880 she was sent to Wellesley College, Massachusetts, one of the top academic schools for women in the U.S. The cold winter climate in the area led to repeated infections, and in one such bought she was stricken with scarlet fever. As a result, she became almost completely deaf.

She graduated in 1884 with a degree in physics and returned home. Uninterested in the limited career opportunities available to women, she grew bored and restless. Her partial hearing loss made socializing difficult, and she was generally older and better educated than most of the unmarried women in the area. She had made a trip to Europe in 1892 to photograph the solar eclipse, but returned with her situation little improved.

In 1893, however, her mother passed away. Life in the home grew more difficult, and she finally wrote to her former instructor at Wellesley, Professor of Physics and Astronomy Sarah Frances Whiting, to see if there was a job opening. Sarah hired her as her assistant, which allowed Annie to take graduate courses at the college. The school had started offering a course in astronomy, which was her true calling. While at Wellesley, Professor Whiting inspired her to learn about spectroscopy. Also during those years, Cannon developed her skills in the new art of photography.

She decided to enroll at Radcliffe women's college at Harvard, which had access to the Harvard College Observatory. In 1896 she was hired as Edward C. Pickering's assistant at the Harvard observatory. She returned to Wellesley in 1894 for graduate study in physics and astronomy. By 1907 she received an M.A. from Wellesley.

Harvard Observatory

Annie Cannon spent most of the remainder of her life working at the Harvard Observatory. Her early studies at the observatory involved variable stars, and she spent much time on their classification. In 1911 she was named curator of photographs at Harvard Observatory.

Missing image
Harvard College Observatory about 1900.

Part of her work at Harvard involved photographing specrograms of stars, then identifying each star according to its spectrum. Pickering and his assistant Williamina Fleming assigned stars a letter according to how much hydrogen could be observed in their spectra. Stars classified as A had the most hydrogen, B the next most, and so on. They developed 22 types in all, but the physical significance of stars of each type was not clear.

Cannon had noticed that stellar temperature was the main distinguishing feature among the different spectra. So she combined the previous classification systems used at the observatory into a simplified system. She reordered the previous types by temperature and eliminated most of the spectral class types because they became redundant.

Working from 1915 until 1924 on what would be published as the Henry Draper Catalogue, Cannon catalogued 225,300 stars and ordered them into stellar spectra of types O, B, A, F, G, K, M. This classification inspired the mnemonic phrase "Oh, Be A Fine Girl - Kiss Me!" still taught to astronomy students today to remember that particular order. Several other variations on the mnemonic also are in use.

Unlike previous classification systems, Cannon's system related the amount of hydrogen observed to a physical property of the stars. This system became the widely-accepted astronomical standard by 1910.

Cannon reviewed photographic plates that contained stellar spectra, then called out each classification to an assistant, who would record the classification. Her hearing difficulty made it possible to focus entirely on her work, and she became exceptionally quick and accurate at analyzing stellar spectra. On average, Cannon classified three stars a minute in sparsely populated regions of the sky, and her speed was half that for denser regions of the sky.

In 1922 she was dispatched to Harvard's observatory at Boyden Station, Peru for six months. At the observatory she photographed the stars that are only visible in the southern hemisphere. After her return, she began working on the Henry Draper Extension, which was published between 1929 and 1949.

In 1931, Cannon became the first woman to receive the Henry Draper Medal from the National Academy of Sciences. In her honor, the American Association of University Women presents the Annie J. Cannon Award in Astronomy each year to a woman starting her astronomical career.

Cannon also was a women's suffrage advocate and a member of the National Women's Party. During her lifetime, Cannon turned over most prize money she received to universities so they could use it for scholarships for young women studying astronomy.

During her life's work, she also discovered over 300 variable stars, 5 novae, and a binary star. Her catalog work resulted in the classification of about 350,000 stars. She continued working at the observatory until age 76, only stopping due to heart disease. Cannon died in Cambridge, Massachusetts.



  • Greenstein, George. 1993. "The Ladies of Observatory Hill," American Scholar, 62: 437-446.
  • Nancy J. Veglahn, Women Scientists, 1991, Facts on File, ISBN 0-8160-2482-0.


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