M 51, also known as the  Tourbillon galaxy  (Whirlpool Galaxy  in English) is a couple of  galaxies located  around  27.4  million light years  in the constellation of  Hunting dogs.

This famous couple is  composed of a  regular spiral galaxy  massive whose diameter is estimated at 100  000  light years and a small  irregular galaxy .

Spring star, it is one of the most famous galaxies of astrophotographers, with very pronounced colors and presenting beautiful nebulae, accentuated here  by the joint use of a Halpha Hydrogen filter.