Online Encyclopedia
Annie Jump Cannon
Annie Jump Cannon ( December 11, 1863 – April 13, 1941), US astronomer, was born to shipbuilder and state senator, Wilson Cannon, and his second wife, Mary Jump, in Dover, Delaware.
She graduated from Wellesley College in 1884 with a degree in physics. She returned to Wellesley in 1894 for graduate study in physics and astronomy. In 1895, she attended Radcliffe College to continue her graduate study. While at Wellesley, Professor of Physics and Astronomy Sarah Frances Whiting inspired her to learn about spectroscopy.
During the years between receiving her first degree and returning for her graduate work, she was stricken with scarlet fever and as a result, she became almost completely deaf.
Also during those years, Cannon developed her skills in the new art of photography. In 1892, she traveled to Spain to photograph the solar eclipse.
In 1896, 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.
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.
Working on what would be published as the Henry Draper Catalogue, Cannon catalogued about 400,000 stars and ordered them into stellar spectra of types O, B, A, F, G, K, M. 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. Unlike previous classification systems, Cannon's system related the amount of hydrogen observed to a physical property of the stars.
Cannon reviewed photographic plates that contained stellar spectra, then called out each classification to an assistant, who would record the classification. 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.
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. During her work, she also discovered over 300 variable stars, 5 novae, and a binary star.
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.
Cannon died in Cambridge, Massachusetts.