3rd Earl of Rosse. Portrait of William Parsons, 3rd Earl of Rosse (1800-1867) and Irish astronomer. He built telescopes, discovered spiral galaxies and named the Crab Nebula. In 1845 Rosse built a reflecting telescope in Ireland with a 183 centimetre (72-inch) diameter mirror known as the Leviathon of Corkstown". Using it in 1845, Rosse was the first to identify the true nature of a spiral galaxy and went on to discover fifteen more. He named the Crab Nebula in 1848, the same year as he was elected to the Royal Society. Further observations were hampered by poor weather conditions and by Rosse's relief work during the Irish potato famine (1845-48)."