History Made Every Day™

LEAVITT, Henrietta Swan

(1868–1921), American astronomer, whose work made possible the first accurate determination of extragalactic distances. While working at the Harvard College Observatory on a survey of Cepheid variable stars (stars the luminosity, or brightness, of which varies in an extremely regular manner) she discovered (1912) that the Cepheids having the greatest average brightness also had the longest periods of variation. The following year, when the Danish astronomer Ejnar Hertzsprung accurately estimated the distances of a few Cepheids, the distances of all Cepheids could be calculated from Leavitt’s period-luminosity correlation. This method greatly increased the scientific knowledge of the physical universe.

An article from Funk & Wagnalls® New Encyclopedia. © 2006 World Almanac Education Group. A WRC Media Company. All rights reserved. Except as otherwise permitted by written agreement, uses of the work inconsistent with U.S. and applicable foreign copyright and related laws are prohibited.

ENCYCLOPEDIA:

LEAVITT, Henrietta Swan

LEAVITT, Henrietta Swan. (1868–1921), American astronomer, whose work made possible the first accurate determination of extragalactic distances. The following year, when the Danish astronomer Ejnar Hertzsprung accurately estimated the distances of . . .

Read More

ENCYCLOPEDIA: ASTRONOMY,

ENCYCLOPEDIA: The Bush Administration

ENCYCLOPEDIA: STAR,

ENCYCLOPEDIA: Populations and Areas of Counties and States