Biography of Annie Jump Cannon, Classifier of Stars

The astronomer who discovered and classified countless stars

Photo of Annie Jump Cannon in profile
Annie Jump Cannon, circa 1925 (Photo: Bettmann / Getty Images).

Annie Jump Cannon (December 11, 1863–April 13, 1941) was an American astronomer whose work in star cataloging led to the development of modern star classification systems. Along with her groundbreaking work in astronomy, Cannon was a suffragist and activist for women’s rights.

Fast Facts: Annie Jump Cannon

  • Known For: American astronomer who created the modern star classification system and broke ground for women in astronomy
  • Born: December 11, 1863 in Dover, Delaware
  • Died: April 13, 1941 in Cambridge, Massachusetts
  • Selected Honors: Honorary doctorates from University of Groningen (1921) and Oxford University (1925), Henry Draper Medal (1931), Ellen Richards Prize (1932), National Women's Hall of Fame (1994)
  • Notable Quote: "Teaching man his relatively small sphere in the creation, it also encourages him by its lessons of the unity of Nature and shows him that his power of comprehension allies him with the great intelligence over-reaching all."

Early Life

Annie Jump Cannon was the eldest of three daughters born to Wilson Cannon and his wife Mary (neè Jump). Wilson Cannon was a state senator in Delaware, as well as a ship builder. It was Mary who encouraged Annie’s education from the very start, teaching her the constellations and encouraging her to pursue her interests in science and math. Throughout Annie’s childhood, mother and daughter stargazed together, using old textbooks to identify and map out the stars they could see from their own attic.

Sometime during her childhood or young adulthood, Annie suffered major hearing loss, possibly due to scarlet fever. Some historians believe she was hard of hearing from childhood onward, while others suggest that she was already a young adult in her post-college years when she lost her hearing. Her hearing loss reportedly made it difficult for her to socialize, so Annie immersed herself more completely in her work. She never married, had children, or had publicly known romantic attachments.

Annie attended Wilmington Conference Academy (known today as Wesley College) and excelled, particularly in math. In 1880, she began studying as Wellesley College, one of the best American colleges for women, where she studied astronomy and physics. She graduated as valedictorian in 1884, then returned home to Delaware.

Teacher, Assistant, Astronomer

In 1894, Annie Jump Cannon suffered a major loss when her mother Mary died. With home life in Delaware becoming more difficult, Annie wrote to her former professor at Wellesley, the physicist and astronomer Sarah Frances Whiting, to ask if she had any job openings. Whiting obliged and hired her as a junior-level physics teacher—which also enabled Annie to continue her education, taking graduate-level courses in physics, spectroscopy, and astronomy.

To continue pursuing her interests, Annie needed access to a better telescope, so she enrolled at Radcliffe College, which had a special arrangement with nearby Harvard to have professors give their lectures both at Harvard and Radcliffe. Annie gained access to the Harvard Observatory, and in 1896, she was hired by its director, Edward C. Pickering, as an assistant.

Pickering hired several women to assist him on his major project: completing the Henry Draper Catalogue, an extensive catalogue with the goal of mapping and defining every star in the sky (up to a photographic magnitude of 9). Funded by Anna Draper, Henry Draper’s widow, the project took up significant manpower and resources.

Creating a Classification System

Soon into the project, a disagreement arose over how to classify the stars they were observing. One woman on the project, Antonia Maury (who was Draper’s niece) argued for a complex system, while another colleague, Williamina Fleming (who was Pickering’s chosen supervisor) wanted a simple system. It was Annie Jump Cannon who figured out a third system as a compromise. She divided stars into the spectral classes O, B, A, F, G, K, M—a system which is still taught to astronomy students today.

Annie’s first catalog of stellar spectra was published in 1901, and her career accelerated from that point on. She received a master’s degree in 1907 from Wellesley College, completing her studies from years earlier. In 1911, she became the Curator of Astronomical Photographs at Harvard, and three years later, she became an honorary member of the Royal Astronomical Society in the U.K. Despite these honors, Annie and her female colleagues were often criticized for working, rather than being housewives, and were often underpaid for long hours and tedious work.

Regardless of criticism, Annie persisted, and her career flourished. In 1921, she was among the first women to receive an honorary doctorate from a European university when the Dutch university Groningen University awarded her an honorary degree in math and astronomy. Four years later, she was awarded an honorary doctorate by Oxford – making her the first woman to receive an honorary doctorate of science from the elite university. Annie also joined the suffragist movement, advocating for women’s rights and, specifically, the extension of the right to vote; the right to vote for all women was finally won in 1928, eight years after the Nineteenth Amendment in 1920.

Annie’s work was noted for being incredibly rapid and accurate. At her peak, she could classify 3 stars per minute, and she classified around 350,000 over the course of her career. She also discovered 300 variable stars, five novas, and one spectroscopic binary star. In 1922, the International Astronomical Union officially adopted Cannon's stellar classification system; it is still used, with only minor changes, to this day. In addition to her work on classifications, she served as a sort of ambassador within the astronomy field, helping forge partnerships among colleagues. She assumed a similar role for the astronomy field’s public-facing work: she wrote books presenting astronomy for public consumption, and she represented professional women at the 1933 World’s Fair.

Retirement and Later Life

Annie Jump Cannon was named the William C. Bond Astronomer at Harvard University in 1938. She remained in that position before retiring in 1940 at the age of 76. Despite being officially retired, however, Annie continued to work in the observatory. In 1935, she created the Annie J. Cannon Prize to honor women’s contributions to the field of astronomy. She continued to help women gain a foothold and gain respect in the scientific community, leading by example while also lifting up the work of fellow women in science.

Annie’s work was continued by some of her colleagues. Most notably, the famous astronomer Cecilia Payne was one of Annie’s collaborators, and she used some of Annie’s data to support her groundbreaking work that determined that stars are composed primarily of hydrogen and helium.

Annie Jump Cannon died on April 13, 1941. Her death came after a long illness and hospitalization. In honor of her countless contributions to astronomy, the American Astronomical Society presents an annual award named for her—the Annie Jump Cannon Award—to female astronomers whose work has been especially distinguished.


  • Des Jardins, Julie. The Madame Curie Complex—The Hidden History of Women in Science. New York: Feminist Press, 2010.
  • Mack, Pamela (1990). "Straying from their orbits: Women in astronomy in America". In Kass-Simon, G.; Farnes, Patricia; Nash, Deborah. Women of Science: Righting the Record. Bloomington: Indiana University Press, 1990.
  • Sobel, Dava. The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars. Penguin: 2016.
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Prahl, Amanda. "Biography of Annie Jump Cannon, Classifier of Stars." ThoughtCo, Feb. 17, 2021, Prahl, Amanda. (2021, February 17). Biography of Annie Jump Cannon, Classifier of Stars. Retrieved from Prahl, Amanda. "Biography of Annie Jump Cannon, Classifier of Stars." ThoughtCo. (accessed April 1, 2023).