Summary: Annie Jump Cannon and Henrietta Swan Leavitt would form the core of the calculation staff at the Harvard College Observatory for nearly two decades. They oversaw the transition of the Observatory from the directorship of Edward Charles Pickering to Harlow Shapley and established the dominant classification systems and physical laws for stellar spectra and variable stars in the early 20th century that would lead to foundational discoveries in the fields of astronomy and astrophysics.
