This is Oriona Nebula (also know as Messier 42 or M42 or NGC 1976. It is a diffuse nebula situated in the Milky Way being south of Orion's Belt in the constellation of Orion. One of the brightest nebulae and visible to the naked eye in the night sky with apparent magnitude 4.0. It has radius of 12 light years. Its distance to earth is 1,344 light years with 3.002 million years age. This nebula was discovered by Christian Huygens.