The 3rd Earl of Rosse, William Parsons, was an Irish astronomer and nobleman born in 1800. He is best known for constructing the Leviathan of Parsonstown, which was the largest telescope in the world during the 19th century. This impressive instrument allowed him to make significant astronomical discoveries, including detailed observations of nebulae. In addition to his work in astronomy, the 3rd Earl of Rosse was also involved in various scientific endeavors and was a member of the Royal Society. He contributed to the advancement of science in Ireland and was recognized for his efforts in promoting scientific education and research during his lifetime.