The Whirlpool Galaxy (also known as Messier 51a, M51a, or NGC 5194) is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus in the constellation Canes Venatici. It was the first galaxy to be classified as a spiral galaxy. Recently it was estimated to be 23 ± 4 million light-years from the Milky Way, but different methods yield distances between 15 and 35 million ly. Messier 51 is one of the best known galaxies in the sky. The galaxy and its companion (NGC 5195) are easily observed by amateur astronomers, and the two galaxies may even be seen with binoculars.
SPONLI is a project about astrophotography, for amateur astronomers.