Annie Jump Cannon

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Annie Jump Cannon was born on December 13, 1863. Her middle name came from her mother’s maiden name. It was from her mother that Annie first learned to love to look at the night sky. From her father she got more than a little of her political side. Wilson Cannon was a shipbuilder before he was elected to the Delaware State Senate. Just two years before Annie was born, he cast the deciding vote that kept Delaware within the Union. Annie was a suffragete.

But astronomers are more familiar with Annie’s astronomical endeavors. Although the climate was not good for women entering scientific fields in the late 19th century, Annie had three things in her favor. First was her family. Her father saw to it that Annie got into Wellesley College in Massachusetts — a rare opportunity for a woman from another state. Second was a sudden mass of work that needed to be done that included classifying stars according to their spectra. The third piece was a job opportunity for women as “computers.”

You see, long before the electronic computer was invented in the 1940’s, the word “computer” was applied to humans — people who did the computations necessary for scientific work.

Anna Draper was the widow of Henry Draper. Henry wanted to put together a comprehensive star catalog which would include classifications based on stellar spectra. But Henry died in 1882 with most of the work undone. Anna gave a large sum of money to the Harvard Observatory and its director, Edward Pickering. She also gave Pickering some advice — hire women. Pickering did so and he paid them 25% of what he would have to pay men for the same job. Still that was better than what women could make in a factory job at that time. It was also work that could be done by someone who is deaf. Annie was partially deaf as a result of scarlet fever that she got while at Wellesley. Another one of Pickering’s “harem” was Henrietta Leavitt. She was also deaf.

Annie Cannon went to work at the Harvard Observatory in 1897. Very soon after she started she noted that there was a problem with the ways that stellar spectra were being classified. The classifications went from A to O with the A stars having the strongest and clearest lines. But Annie noticed that the B stars were actually hotter and represented a more “evolved” star. Later it would be clear that the O stars were even hotter than B stars. Other classifications such as C, D and E were similar to other stars but the spectragraphs showed doubled lines which were most likely errors in the equipment. So the order of the stellar spectra became O, B, A, F, G, K and M. It was Annie herself who came up with the mnemonic used by many students since then to remember the order: “Oh be a fine girl, kiss me.”

From 1911 to 1915, the intense work on the stellar spectra was done and in 1918, the first volumn of the Henry Draper Catalogue was published. It would be fully published in 1924 when the ninth and “final” volume was published. I say final in quotes because there were extensions. The last was published in 1949, 8 years after Annie died but with her name still on it.

During her lifetime, Annie received many awards and honorary degrees. The awards included the Draper medal. Even to the present day, only one other woman has won this award and that person shared it with her male collaborator.

There were so many accolades after she died. She had a “priceless ability of being good company for all kinds of people ... her character, distinguished by modesty and unselfishness, was human nature at its best”. She was called “a continued source of inspiration to all who knew her. This is especially true for women who work in astronomy”. Another notice said that besides being a pioneer she was “genuinely interested in all persons”.