Rosse, Earl of (1800-1867), was an Irish astronomer who built a reflecting telescope that was the largest and most powerful in the world. The telescope, completed in 1845, had a mirror that was 72 inches (183 centimeters) in diameter. The telescope stood in the grounds of Rosse’s family home at Birr Castle, in King’s County (now County Offaly), Ireland. With the telescope, Lord Rosse made detailed observations of the heavens. In particular, he studied the hazy masses called nebulae.
William Parsons was born in York, England, on June 17, 1800. He became the third Earl of Rosse in 1841. He was educated at Trinity College, Dublin, and at Magdalen College, Oxford University. He died in Monkstown, near Dublin, on Oct. 31, 1867.
