Henrietta Swan LeavittBorn 4 Jul 1868; died 12 Dec 1921 at age 53.American astronomer who wasknownfor her discovery of the relationship between period and luminosity in Cepheid variables, pulsating stars that vary regularly in brightness in periods ranging from a few days to several months. Leavitt's greatest discovery came from her study of 1777 variable stars in the Magellanic Clouds. She determined the periods of 25 Cepheid variables and in 1912 announced what has since become known as the famous Period-Luminosity relation: “since the variables are probably nearly the same distance from the earth, their periods are apparently associated with their actual emission of light, as determined by their mass, density, and surface brightness.”Today the Period-Luminosity relation is used to calculate the distances of galaxies. |
