Rosse, William Parsons, 3rd earl

Rosse, William Parsons, 3rd earl of

(born June 17, 1800, York, Eng.—died Oct. 31, 1867, Monkstown, County Cork, Ire.) Irish astronomer. His “Leviathan,” 54 ft (16.5 m) long, was the largest reflecting telescope of the 19th century, and its mirror had a diameter of 72 in. (183 cm). With it Rosse discovered the spiral shape of many objects then classed as nebulae, now recognized as galaxies, and he studied and named the Crab Nebula. He was also the first to discover binary and triple stars. As Lord Oxmantown, he sat in the House of Commons (1821–34); on inheriting his father's earldom in 1841, he joined the House of Lords.