son of J. W. Draper. From 1863, using telescopes and spectrographs of his own construction, he took 1500 high-quality lunar photographs and obtained the best contemporary photographs of the Sun’s spectrum. In 1872 he recorded the first spectrum of another star, Vega, and identified in it prominent hydrogen lines. In 1879 he switched to dry photographic plates and obtained excellent spectra of stars, the Moon, Mars, Jupiter, the comet now designated C/1881 K1, and the Orion Nebula. After his death, his widow Mary Anna Draper, née Palmer (1839–1914), donated the funds that made possible the Henry Draper Catalogue.