Henrietta Swan Leavitt

Who was Henrietta Swan Leavitt?

Henrietta Swan Leavitt was an American astronomer. A graduate of Radcliffe College, Leavitt started working at the Harvard College Observatory as a "computer" in 1893, examining photographic plates in order to measure and catalog the brightness of stars. Leavitt discovered the relation between the luminosity and the period of Cepheid variable stars. Though she received little recognition in her lifetime, it was her discovery that first allowed astronomers to measure the distance between the Earth and faraway galaxies. After Leavitt's death, Edwin Hubble used the luminosity-period relation for Cepheids to determine that the Milky Way is not the only galaxy in the observable universe, and that the universe is expanding.