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 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.