Annie Jump Cannon
 
Annie Jump Cannon was born on December 11, 1863, in Dover, Delaware.

She was the eldest of three daughters born to Wilson Cannon, a Delaware shipbuilder and state senator, and his second wife, Mary Jump.

Cannon's mother was the first person to teach her the constellations and encouraged her to follow her own interests, suggesting that she pursue studies in mathematics, chemistry, and biology at Wellesley College.

Cannon took her mother's advice and pursued her love of astronomy.

Cannon suffered hearing loss sometime during her childhood or early adult years.

Sources vary on the time frame and actual cause, although it is sometimes attributed to scarlet fever.

There are claims this hearing loss made it difficult for her to socialize, resulting in Cannon immersing herself in her work. She never married or had children.

Education
At Wilmington Conference Academy (today known as Wesley College), Cannon was a promising student, particularly in mathematics.

In 1880, Cannon was sent to Wellesley College in Massachusetts, one of the top academic schools for women in the U.S., where she studied physics and astronomy.

Cannon studied under Sarah Frances Whiting, one of the few women physicists in the United States at the time, and went on to become the valedictorian at Wellesley College.

She graduated with a degree in physics in 1884 and returned home to Delaware for a decade.

This was partly due to the fact that there were limited opportunities available to women in the careers that Cannon was interested in.

Also during these years, Cannon developed her skills in the new art of photography.

In 1892 she traveled through Europe taking photographs with her Blair box camera.

After she returned home her prose and photos from Spain were published in pamphlet called "In the Footsteps of Columbus" by the Blair Company, and distributed as a souvenir at the Chicago World's Columbian Exposition of 1893.

Soon afterwards, Cannon was stricken with scarlet fever that rendered her nearly deaf.

This hearing loss made it difficult for Cannon to socialize.

As a result, she immersed herself in her work.

She never married or had children.

In 1894, Cannon's mother died and life at home grew more difficult.

She finally wrote to her former instructor at Wellesley, professor Sarah Frances Whiting, to see if there was a job opening.

Whiting hired her as a junior physics teacher at the college.

This opportunity also allowed Cannon to take graduate courses at the college in physics and astronomy.

Whiting also inspired Cannon to learn about spectroscopy.

In order to gain access to a better telescope, Cannon enrolled at Radcliffe College as a "special student", continuing her studies of astronomy.

Radcliffe was set up near Harvard College for Harvard professors to repeat their lectures to the young Radcliffe women.

This relationship gave Cannon access to the Harvard College Observatory.

In 1896, Edward C. Pickering hired her as his assistant at the Observatory, and by 1907, Cannon finished her studies and received an M.A. from Wellesley.

Professional history
In 1896, Cannon became a member of "Pickering’s Women," the women hired by Harvard Observatory director Edward C. Pickering to complete the Henry Draper Catalog, mapping and defining every star in the sky to photographic magnitude of about 9.

Anna Draper, the widow of wealthy physician and amateur astronomer Henry Draper, set up a fund to support the work.

Men at the laboratory did the labor of operating the telescopes and taking photographs while the women examined the data, carried out astronomical calculations, and cataloged those photographs during the day.

Pickering made the Catalog a long-term project to obtain the optical spectra of as many stars as possible and to index and classify stars by spectra.

If making measurements was hard, the development of a reasonable classification was at least as difficult.

Not long after work began on the Draper Catalog, a disagreement developed as to how to classify the stars.

The analysis was first started by Nettie Farrar, who left a few months later to be married.

This left the problem to the ideas of Henry Draper's niece Antonia Maury (who insisted on a complex classification system) and Williamina Fleming (who was overseeing the project for Pickering, and wanted a much more simple, straightforward approach).

Cannon negotiated a compromise: 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 O, B, A, F, G, K, M.

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 catalogs.

Cannon came up with the mnemonic of "Oh Be a Fine Girl, Kiss Me" as a way to remember stellar classification.

Cannon published her first catalog of stellar spectra in 1901.

Cannon and the other women at the Observatory were criticized at first for being "out of their place" and not being housewives.

In fact, women could only get as high as assistants in this line of work and were only paid 25 cents an hour for seven hours a day, six days a week.

Cannon dominated this field because of her "tidiness" and patience for the tedious work, and even helped the men in the observatory gain popularity.

Cannon helped broker partnerships and exchanges of equipment between men in the international community and assumed an ambassador-like role outside of it.

She wrote books and articles to increase astronomy's status, and in 1933, she represented professional women at the World's Fair in Chicago.

Cannon's determination and hard work paid off.

She classified more stars in a lifetime than anyone else, with a total of around 500,000 stars.

She also discovered 300 variable stars, five novas, and one spectroscopic binary, creating a bibliography that included about 200,000 references.

Cannon could classify three stars a minute just by looking at their spectral patterns and, if using a magnifying glass, could classify stars down to the ninth magnitude, around 16 times fainter than the human eye can see.

On May 9, 1922, the International Astronomical Union passed the resolution to formally adopt Cannon's stellar classification system, and with only minor changes, it is still being used for classification today.

The astronomer Cecilia Payne collaborated with Cannon and used Cannon's data to show that the stars were composed mainly of hydrogen and helium.

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