The Sky at Night S18 E09 Lord Rosse's Great Telescope

A century ago, the most powerful telescope in the world was the great 72-inch reflector at Birr Castle in Eire, with which its builder, the 3rd Earl of Rosse, discovered the spiral galaxies. Patrick Moore visits Birr, and talks to the present Earl and Countess of Rosse about the past and future of the great telescope.