M42, the Orion Nebula, also known as NGC 1796 is a diffuse nebula below Orion's Belt. It is one of the brightest nebulae in the sky, and can be observed with the naked eye during the night. It is some 1,270 light years away, and has a diameter of some 24 light years. Some documents call it the Great Nebula in Orion, and the oldest texts call it Ensis, a latin word meaning "sword", a name that is also given to the star Eta Orionis, which we can observe very close to the nebula. Credit: J. C. Casado, Miquel Serra-Ricart y D. Padrón/IAC.