M51 - Whirlpool Galaxy

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.

It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy. It is 31 million light-years (9.5 megaparsecs/Mpc) away and 23.58 kiloparsecs (76,900 ly) in diameter.