M51

M51 in Ha, OIII and Blue, The famous Whirlpool galaxy M51 was one of Charles Messier's original discoveries. He discovered it on October 13, 1773, when observing a comet, and described it as a "very faint nebula, without stars" which is difficult to see. Its companion, NGC 5195, was discovered in 1781 by his friend, Pierre M??chain, so that it is mentioned in Messier's 1784 catalog: 'It is double, each has a bright center, which are separated 4'35". The two atmospheres touch each other, the one is even fainter than the other.' NGC 5195 was also recorded by William Herschel, who assigned it the number H I.186.