M51, also known as the Whirlpool Galaxy, is a stunning spiral galaxy located about 23 million light-years away in the constellation Canes Venatici. It is famous for its well-defined spiral arms and its interaction with a smaller companion galaxy, NGC 5195, which is partially embedded in one of its arms. The galaxy's distinctive structure and the dynamic gravitational interaction between M51 and NGC 5195 create striking tidal features, such as elongated tails of gas and stars. M51 is often studied by astronomers due to its relatively close proximity, which provides valuable insights into galaxy formation and evolution. It was the first galaxy to be recognized as a spiral. (photo by me, 250 mm lens with 3 hours of integration time)