The Whirlpool Galaxy (M51) was the first celestial object ever to be identified as being a spiral. The discovery was made by William Parsons, Third Earl of Rosse (Ireland) in 1845. Parsons used his own telescope, The Leviathan, then the world’s largest, at Birr Castle, County Offaly, Ireland.

This discovery paved the way for the realisation that these ‘spiral nebulae’ were actually distinct from our own galaxy and were whole seperate galaxies.