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Annie Jump Cannon - an Astronomer Who Measured the Stars

Updated on April 30, 2019

The Early Years

Born in Dover, Delaware in 1863, Annie Jump Cannon was the eldest daughter of State Senator and ship builder, Wilson Cannon. Wilson Cannon, and his second wife Mary Jump, had Annie and two sons, Wilson Lee Cannon, Jr. and Robert Barrett Cannon together. At an early age Mary taught Annie the constellations, how to identify them and the stories behind them. This fueled Annie's interest in astronomy. Cannon's mother was the one who ultimately encouraged her to pursue her interest and suggested that Annie study math, chemistry, or biology at Wellesley College. The cold winters of Delaware did not agree with Annie, on one occasion she contracted Scarlett Fever, this resulted in a significant hearing loss.

Sources are in disagreement as to whether she lost her hearing as a child or later in life, however, they do agree that she developed the affliction and was not born with it. These same sources agree that by the time she had begun her professional life as an astronomer, she had completely lost the ability to hear. As time progressed, her hearing continued to diminish until she was rendered completely deaf.


With her mother's encouragement, Cannon attended Wellesley College, one of the few and best colleges at the time that opened its doors to women, where she studied astronomy and physics. Cannon had acquired the ability to read lips which enabled her to comprehend the lectures. Cannon studied under Sarah Francis Whiting, one of only a handful of women physicists in the United States at the time. She graduated as Valedictorian from Wellesley College in 1884 with her degree in physics.

The fields for women were minimal at best in 1884, this led to Cannon dabbling in photography and traveling after she graduated. Her hearing loss made socializing difficult, and despite traveling to Europe to photograph a solar eclipse in 1892, she was restless. The career fields of interest for Cannon were limited, as physics and astronomy were very much "men's fields." She returned home to Delaware shortly after the eclipse. Her prose and photo's from her trip through Europe were published in a pamphlet called "In the Footsteps of Columbus," in 1893. Her happiness upon returning was short lived as her mother died in 1894.

The loss of her mother inspired Cannon to no longer wait around for opportunities to present themselves. She wrote to her former Wellesley professors asking about job openings. She was hired as a junior physics teacher which allowed her, in that same year, to take graduate level astronomy courses. These courses made her proficient in spectroscopy (the process by which spectral colors of the stars is recorded) and photography. In 1895, she enrolled at Radcliffe College as a "special student" so she could study under Edward C. Pickering, director of the Harvard College Observatory. Harvard professors worked in conjunction with Radcliff College and would often repeat their lectures for the women at Radcliff who were studying astronomy. Enrolling at Radcliff also gave Cannon access to better equipment than she had at Wellesley.

Her Professional Work Begins

By 1896 Cannon was hired as Edward C. Pickering's assistant at the Observatory. She had become part of a group known as "Pickering's Women," whose goal was to complete the Henry Draper Catalogue by defining and mapping every star in the sky to a magnitude of 9, or 16x less visible then the human eye can see. Henry Draper's wealthy widow, Anna, was responsible for funding this project. Draper had the men operate the telescopes and take photographs, while insisting the women examined the data, carried out the calculations, and catalogued the photographs.

Cannon was not alone in this endeavor, she was joined by Williamina P.S. Fleming. Together, Cannon, Fleming, and Pickering took on the ambitious project of recording, classifying, and cataloging the spectra of various stars. This project, which first began in 1885, used surface temperatures as a means of classification. Cannon wasted no time, soon after beginning at the Observatory she discovered SS Cygni, a "dwarf nova" that repeats its outbursts roughly every 60 days. Pickering made the short-term project into a long term endeavor in order to obtain optical spectra of as many stars as possible. While working at the Observatory, Cannon continued her studies and received her M.A. from Wellesley in 1907.

There were many who criticized Cannon and the other women who worked at the observatory saying they were "out of their place," because they chose to work instead of be in the kitchen barefoot and pregnant. They were also criticized because many never married or had children. Even though Cannon dominated the field of astronomy because of her tidiness and patience for the tediousness of the work, women could not rise above the level of assistant. The men she worked with in the observatory gained popularity because of Cannon's reputation. Cannon, and the other women she worked with, usually worked seven hour days, six days a week. Beyond the work within the observatory itself, Cannon served an ambassador-like role, helping create partnerships and equipment exchanges on the international level.

The Harvard Computers - Origins of the Stellar Classification System

Measuring and Cataloging the Stars

Measuring the stars was difficult and creating a way to catalog them took trial and error. Nettie Farrar first started the classification process, she left to get married within a few months and left the problem to Antonia Maury, Henry Draper's niece. Maury wanted a complex classification system which conflicted with Fleming's idea for a simpler approach. Fleming had devised a 22 level classification system for the stars. When Cannon took over she negotiated a compromise between Maury and Fleming and created the OBAFGKM classification system. Cannon concluded that none of the systems was sufficient for her needs, so she merged two of them. Her system had been largely, yet unofficially, adopted within the scientific community by 1910.

On May 9, 1922, the International Astronomical Union passed a measure to formally adopt Cannon's stellar classification system with a few minor changes (such as the order), her OBAFGKM system maintains itself as the standard today. In this classification system, an “O” type star is very hot and the “M” type stars are much cooler. Our sun is a type “G” star which is a rather common type of star. In classrooms all over the country, it is memorized as "Oh, Be A Fine Girl--- Kiss Me." During her lifetime, Cannon cataloged more stars than any other single person in history, around 350,000. Astronomer Cecilia Payne and Cannon collaborated briefly to determine the composition of stars, they used the data Cannon had collected to determine that stars were mainly composed of helium and hydrogen. Cannon classified around three stars per minute using her system. Just by looking at the spectral patterns she was able to classify stars. She published her first catalog of stellar spectra in 1901.

In 1911, Cannon officially succeeded Fleming as the curator of astronomical photographs at Harvard University Observatory. Even with her new title, she and the other women at the observatory only made $0.25 per hour, this was less than the Harvard secretaries made, but she did it for the love of astronomy. She authored several books during her career and, ultimately, helped popularize astronomy in the public domain.

Cannon published various catalogues with stars and their classifications, 300 of these she discovered herself. Her work is also published in nine volumes known as the Henry Draper Catalogue. In addition to her enthusiasm for astronomy, her downright passion for it, Cannon's colleague's knew her to be exceedingly patient. In 1924, she extended her existing catalogue by adding over 10,000 new stars existing down to the 11th magnitude. This work was, and still is, an invaluable asset to astronomers today on issues from observation, theory, and even philosophy. This work also includes the discovery of five novae, a classification of exploding stars. 86,000 star classifications were published posthumously in 1949.

Spectrum of a G5III type star showing prominent Hydrogen, Helium, and Sodium absorption lines.
Spectrum of a G5III type star showing prominent Hydrogen, Helium, and Sodium absorption lines. | Source

Awards and Honors

The Nova Medal was given to Cannon by the American Association of Variable Star Observers in 1922. Years later, in 1925, Cannon set another one of her "firsts" when she was awarded with an honorary doctorate from the University of Oxford, the first woman to receive such an honor. This was followed by the Henry Draper Medal of the National Academy of Sciences in 1931, which only one other woman has ever won. Cannon was also the first woman to be elected as an officer in the American Astronomical Society. During her time, the National League of Women Voters named her one of the twelve greatest living American Women of all time. She even represented professional women everywhere at the 1933 World's Fair in Chicago. She was also nominated for membership in the National Academy of Sciences, she was not elected because Raymond Pearl made an issue of her deafness.

Shortly after becoming an officer for the American Astronomical Society, she won the Ellen Richards Research Prize. She used the money from the award to create the Annie J. Cannon award which is given out to a female astronomer in North America, within five years of receiving her doctorate, who has contributed notably to the field of Astronomy. The award now comes with a $1,500 prize and an expenses paid opportunity to speak at the yearly AAS convention.

During Cannon's career she received five other honorary doctorates, one from the University of Delaware, Oglethorpe University, and Holyoke College. In 1938, Cannon was the William Cranch Bond Professor of Astronomy, a title given to astronomers at Harvard who have special recognition in their field. This was the first and only award of recognition to be bestowed upon her from Harvard University. It came towards the end of her career and just three year before her death.

The Final Years

In 1940, the year before her death, Cannon formerly retired from the Harvard Observatory, as is often seen with those dedicated to their field though, she continued her work until the day she died, April 13, 1941, Cambridge, Massachusetts. She was 77 years old. In regards to her co-workers, Cannon was always kind. She was noted as commenting about Williamina Paton Fleming that "A life spent in routine of the sciences need not destroy the attractive human element of a woman's nature."

Her obituaries can be found in "Science" May 9, 1941. Written by Cecilia Payne Gaposchkin and in "Nature" June 14, 1941 written by R.L. Waterfield, both of these obituaries pay homage to Annie's personality, not just her scientific contributions.

During her life, and her career, Annie Jump Cannon helped women gain respect and acceptance within the scientific community. Though she was busy with her first love, astronomy, Cannon was also an outspoken suffragist and aided in the women's civil rights movement. She helped a generation of women, who had no desire to be a housewife, get out and create careers of their own, despite the odds that were against them. The length of Cannon's career extended more than 40 years. In this time she never married and bore no children, some say it was because of the awkwardness from her inability to hear so she immersed herself in work, but others insist it is because she was already married... to the stars.


Cannon, Annie J. In the Footsteps of Columbus (Annotated) Introduction and Biography Included. C&D Publications. 2015.

Carey, Charles W. Jr. American Scientists. Facts on File. 2006.


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    • 1701TheOriginal profile image

      Leonard Kelley 

      4 years ago

      Another excellent insight into the background of astronomy. Well done!

    • sangre profile image

      Sp Greaney 

      4 years ago from Ireland

      Wow, what a fantastic woman. Just goes to show that if you have the ambition and passion to achieve something, you can. Great Hub.


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