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 ucleus in the constellation Canes Venatici. It was the first galaxy to be classified as a spiral alaxy.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 light-years. 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. The Whirlpool Galaxy is also a popular target for professional astronomers, who
Messier 51 and ngc 5195 are easily observed by amateur astronomers
study it to further understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions. understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions. Stars are usually formed in the center of the galaxy. The present efficiency of star formation, defined as the ratio of mass of new stars to the mass of star-forming gas, is only ~1%, quite comparable to the global value for the Milky Way and other galaxies. It is estimated that the current high rate of star formation can last no more than another 100 million years or so.