Henrietta Swan Leavitt
1868–1921, Lancaster, Massachusetts, United States, Cambridge, Massachusetts, United States
American astronomer who discovered the period–luminosity relation of Cepheid variable stars, providing a yardstick for cosmic distances.
Leavitt was born in Lancaster, Massachusetts, and graduated from the Oberlin College preparatory program and the Society for Collegiate Instruction of Women, later Radcliffe College. She began working at the Harvard College Observatory in 1895, initially as a volunteer, and later joined its permanent staff. She studied photographic plates, comparing changes in the brightness of thousands of stars.
In 1912 she reported that Cepheids in the Small Magellanic Cloud with longer periods are intrinsically brighter. Because Cepheids can establish relative distances and calibrate the distances of galaxies, this discovery became a crucial link in extending the known scale of the universe.
Workplaces: Harvard College Observatory
United States