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The Whirlpool Galaxy M51 and NGC 5195 in Canes Venatici the hunting dogs                    

The 'tail' at upper left was a separate galaxy captured in a collision with the larger one. First discovered in 1773 by "Comet Ferret" Charles Messier, his friend Pierre Mechain spotted the smaller component in 1781. Sixty-four years later, Ireland's William Parsons (Lord Rosse) first observed its spiral structure with his leviathan reflector. Though galaxies were not confirmed to be beyond our Milky Way until Edwin Hubble, Rosse was the first to define the nature of them with his observations of this object.