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"The entirety of the Orion Nebula extends across a 10° region of the sky, and includes neutral clouds of gas and dust, associations of stars, ionized volumes of gas and reflection nebulae."

The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated south[b] of Orion's Belt. 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 1,270 light years away +/- 76 light years[2] away (previous distance estimates of 1500 light years have been replaced with newer measurements), and is the closest region of star formation to Earth. The M42 nebula is estimated to be 30 light years across. Older texts frequently referred to ...

The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated south[b] of Orion's Belt. 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 1,270 light years away +/- 76 light years[2] away (previous distance estimates of 1500 light years have been replaced with newer measurements), and is the closest region of star formation to Earth. The M42 nebula is estimated to be 30 light years across. Older texts frequently referred to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula. Yet older, astrological texts refer to it as Ensis, which is also the name of the star Eta Orionis.[5]

The Orion Nebula is considered to be one of the most scrutinized and photographed objects in the night sky, and is among the most intensely studied celestial features.[6] The nebula has revealed much about the process of how stars and planetary systems are formed from collapsing clouds of gas and dust. Astronomers have directly observed protoplanetary disks, brown dwarfs, intense and turbulent motions of the gas, and the photo-ionizing effects of massive nearby stars in the nebula.

(a) A large cloud of gas and dust giving birth to young stars in the constellation Orion and visible to the naked eye. It is an HII region 1500 light-years away.
(b) An HII region about 500 pc distant, barely visible to the naked eye in the center of Orion's sword. It is undoubtedly a region where stars are being born; young O stars and many T Tauri variables are associated with it, and its members are extreme Population I. Probably no more than 20,000 years old. It is also an X-ray source (3U 0527-05 and M42, NGC 1976).