Henrietta Leavitt discovers the relation between the period and luminosity of classical Cepheid variable stars. This period-luminosity (P-L) relation made possible measurements of the distances of stars from the earth and the determination of intergalactic distances by determining the distances from the earth of stars in galaxies outside our own. This relation remains of great importance in the determination of astronomical distances.
This timeline entry suggestion courtesy of
Robert Williams MRSC.
