The Whirlpool Galaxy M51

In the spring of 1845, William Parsons, the Third Earl of Rosse, began observing with his great six-foot reflecting telescope - the ‘Leviathan of Parsonstown’ at Birr Castle, in Ireland’s County Offaly. After he had put up with bad weather for a few weeks, the conditions became cold and dry and he turned the world’s largest telescope towards M51 [a galaxy earlier sighted by Charles Messier]. The Earl was excited by what he was the world’s first human to see: spiral patterns of stars, seemingly swirling in great ‘spiral convolutions’ about the center of the galaxy. This was before the availability of photographic plates and so the Earl did what all astronomers then did: he made careful drawings of his observations… if you look at [Van Gogh’s] most famous work, The Starry Night, with the eyes of an astronomer, there is something familiar about the sky in this small painting… No one could ever have seen the spiral pattern of stars until they had looked through Rosse’s telescope or seen his drawings.

- John Barrow (from Cosmic Imagery, 2008)