Henrietta Leavitt (1868-1921)

American astronomer. Born on 4 July 1868 in Lancaster, Massachusetts. Henrietta studied at Oberlin College for two years (1886-1888) before suffering an illness which left her severely deaf. She transferred to Radcliffe University where she graduated in 1892.

Her interest in astronomy led her to volunteer at Harvard College Observatory in 1895. She was appointed to the permanent staff in 1902 and soon became head of the photographic photometry department.

Much of her work was on a class of stars called Cepheid variables. The brightness of these stars varies regularly, and in 1912 she was able to show a relationship between the brightness of the stars and the period of variation. This was important as a distance indicator for the stars.

In 1913 she also developed a method for photographing, measuring and classifying the brightness of stars which became known as the Harvard Standard. Through her researches she discovered more than 2400 variable stars and worked at Harvard College Observatory up until her death from cancer in Cambridge, Massachusetts, on 12 December 1921.