Above is a picture of the Whirlpool Galaxy, a spiral galaxy in the constellation Canes Venatici (the hunting dogs held on a leash by Bootes as he hunts for the bears Ursa Major and Ursa Minor, itself a minor constellation invented by Johannes Hevelius in 1687).  The whirlpool galaxy is also known either as M51 (because it was the  51st object discovered by Charles Messier in 1773) or NGC 5194 (in the "New Galactic Catalogue"). It can be seen with a pair of binoculars at the end of the handle of the big dipper.

Containing about 160 billion suns and about 65,000 light years in diameter, the whirlpool galaxy is 31 million light years away and is the first galaxy in which a spiral structure was observed. This was accomplished by the Third Earl of Rosse in 1845 with his famed "Leviathan" telescope, a 72" diameter speculum metal telescope elevated within an immense wooden scaffolding.  Astronomers speculate that the pronounced spiral structure of M51 is due to its gravitational interaction with its smaller galactic neighbor NGC 5195, discovered in 1781 by a friend of Messier's, Pierre Mechain. The galactic pair are shown below.