Finding a Cosmic Yardstick.

LEAVITT, Henrietta Swan, 1868-1921; WOMEN astronomers; ASTRONOMICAL observations; SCIENTIFIC discoveries; LUMINOSITY distance; CEPHEIDS; HARVARD College Observatory

The article discusses the achievements in astronomy by U.S. astronomer Henrietta Swan Leavitt and how her painstaking observations were the inspiration for finding alternate ways to determine the distances to far-off celestial bodies. In the 1890's the Harvard College Observatory established an observatory station in Peru, in an attempt to classify the brightest stars by their chemical spectra. The observatory director, Edward C. Pickering, hired astronomer Henrietta Swan Leavitt whose job it was to gauge the magnitude of stars by assessing their spots as imprinted on a photographic plate. Topics include Leavitt's observations which she published in the book "Annals of the Astronomical Observatory of Harvard College," and her discoveries while studying variable stars called Cepheids.