Draper, Henry (1837–1882)

US astronomer. He used a mass spectrograph of his own devising to obtain high-quality spectra of celestial objects. His work is commemorated by the Henry Draper Catalogue of stellar spectral types.

Draper built an observatory in Hastings-on-Hudson, New York. By 1873, he had devised a spectrograph. He was director of the photographic department of the US commission to observe the transit of Venus 1874. Later he spectrographically studied the Moon, Mars, Jupiter, the comet 1881 III, and the Orion nebula. He also succeeded in obtaining photographs of stars that were too faint to be seen with the same telescope by using exposure times of more than 140 minutes.

Draper was born in Virginia and studied medicine at the University of the City of New York. Travelling in Europe, he became interested in telescope-making and photography. In 1860, he was appointed professor of natural science at the University of the City of New York.

The Harvard College Observatory carried out a programme 1886–97 to establish a comprehensive classification scheme for stars and a catalogue of spectra. This project was funded by Draper's legacy and the result was the Henry Draper Catalogue.