Annie Jump Cannon was an American astronomer whose pioneering work in stellar classification laid the foundations for modern astrophysics. Born in 1863, she studied physics and astronomy at Wellesley College, graduating in 1884, before continuing her studies at Radcliffe College under the guidance of Edward C. Pickering at the Harvard College Observatory.
At a time when women were largely excluded from mainstream scientific circles, Cannon worked as part of a team of female astronomers known as the “Harvard Computers.” Despite facing significant institutional barriers, she revolutionized the field with her methodical approach to categorizing stars based on their spectral characteristics. She developed the Harvard Classification Scheme, ordering stars by surface temperature using the now-famous “OBAFGKM” sequence – a system that remains in use today.
Although not the first to attempt spectral classification, Cannon’s painstaking analysis – cataloguing around 350,000 stars over four decades – refined earlier systems into one that was both practical and scalable. Her work was instrumental in confirming the relationship between a star’s color and its temperature, an insight that became a cornerstone of astrophysics.
Beyond her technical contributions, Cannon was a champion of women in science. She became the first woman to receive an honorary doctorate from the University of Oxford in 1925 and was also the first woman elected as an officer of the American Astronomical Society. The Annie Jump Cannon Award in Astronomy, established in her honor, continues to support early-career female astronomers.