By the end of the 19th century, astronomers had identified myriad stars in the night sky. Edward C. Pickering of the Harvard College Observatory recognized the need to organize and map the hundreds of thousands of stars according to their photographic magnitude. In 1896, he hired a precocious young woman named Annie Jump Cannon to assist him, jump starting, as it were, the career of one of America’s foremost women astronomers. (Good move, Ed!)
An American Girl
Annie’s upbringing and education differed significantly from predecessors such as Caroline Herschel and Mary Somerville. The daughter of a Delaware shipbuilder and politician, she enjoyed a conventional education for American children of the time. Her mother taught her the constellations and encouraged her to pursue studies in mathematics and the sciences. She was an outstanding student at Wilmington Conference Academy (now Wesley College) and was admitted to Wellesley College (one of the renowned Seven Sisters colleges), from which she was graduated with a degree in physics, in 1884.
After college, Annie became highly skilled in photography, a craft that would be of great use in her later career as an astronomer. A number of her photos from a sojourn in Spain were published in a pamphlet entitled “In the Footsteps of Columbus” that was distributed at Chicago’s Columbian Exposition, in 1893.
After her mother died, in 1894, Cannon was hired to the faculty of Wellesley as a physics instructor. She took the opportunity also to enroll as a special student at Radcliffe College, which gave her access to Harvard University’s superior telescope. Soon, Edward Pickering knocked on her door, and her exemplary career was launched.
A Diplomatic Astronomer
When Annie was brought on as one of “Pickering’s Women” at the Harvard Observatory, she set to work helping to complete the Henry Draper Catalogue of over 200,000 stars. Her particular area of focus in the project was stars of the Southern Hemisphere. Not only did she have a remarkable aptitude for quickly examining photographic plates (identifying as many as three stars per minute), but she also demonstrated an invaluable talent for negotiating solutions to disputes regarding methods of classification for the Draper Catalogue.
Cannon’s diplomatic efforts led to the adoption of a standardized classification system. Two of her Harvard Observatory colleagues, Williamina Fleming and Antonia Maury had devised separate systems (one alphabetical and the other Roman numeric) for classifying stellar spectra. Cannon combined and simplified the two approaches into a single system in which the spectra were recognized as representing stellar temperatures. Her system was first used in a catalogue of 1,112 stars published in 1901; the system is still in use by astronomers today.
Over more than 40 years as an astronomer, Cannon put her diplomatic skills to use many times. She also classified approximately 350,000 stars (more than any of her colleagues) and is credited with discovery of over 300 variable stars, five novae, and one spectroscopic binary.
The Well-Honored Professional
As Cannon’s contributions to astronomy piled one upon another over decades, so did the recognition she received from astronomical organizations and academic institutions. She was the first woman to receive an honorary degree from Oxford University, in 1925, and the first woman officer of the American Astronomical Society. In 1931, Cannon was awarded the Henry Draper Medal by the National Academy of Sciences. Harvard finally appointed her to its senior faculty as the William Cranch Bond Professor of Astronomy, in 1938, three years before she died.
Perhaps Annie Cannon’s most enduring legacy stems from her willingness to act as a model for many female astronomers and her determination to help them gain greater acceptance in the field. In 1933, the American Astronomical Society established the Annie Jump Cannon Award to honor North American women for their contributions to the science. The Cannon Award has been received by 43 women, to date, and remains one of the most prestigious such prizes in astronomy.