 The Orion Nebula ( also known as Messier 42 , M42 , or NGC 1976 ) is a diffuse nebula situated in the Milky Way , being south of Orion 's Belt in the constellation of Orion . It is one of the brightest nebulae , and is visible to the naked eye in the night sky . M42 is located at a distance of 1 @,@ 344 ± 20 light years and is the closest region of massive star formation to Earth . The M42 nebula is estimated to be 24 light years across . It has a mass of about 2000 times the mass of the Sun . Older texts frequently refer to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula . 
