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Orion Nebula

Great Nebula in Orion, M42, NGC 1976

Star-forming Region in Orion

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Proper NamesOrion Nebula, Great Nebula in Orion
Messier NumberM42 (associated with M43)
NGC/IC NumberNGC 1976 (associated with NGC 1982)
ConstellationOrion
Right Ascension5h 35m 36s
Declination-5° 16' 00"
Distance1,350 light years
400 parsecs
MagnitudeApparent: +4.0
Absolute: -4.1
Mean DiameterApparent: 1° 18'
Actual: 25 light years
Associated Star(s)The Trapezium
Optimum VisibilityDecember/January
Location of the Orion Nebula

The Orion Nebula is easy to locate in the sky. It lies in the central parts of the chain of stars known as the Sword of Orion, running southwards from the Hunter's unmistakable bright Belt of three bright stars.

A view of the Orion Nebula

An overall view of the Orion Nebula, along with M43. The larger scale image on the left shows an area that lies in the approximate centre of this illustration.

Relative Galactic Position of the Orion Nebula

Though it lies some 1,300 light years from the Solar System, on a Galactic scale the Orion Nebula is a relatively nearby phenomenon. From Earth's perspective, it lies in the direction of the Galaxy's rim.

Not only is the Orion Nebula one of the most spectacular of nebulae, but it is also one of the easiest to locate, lying in the middle of the conspicuous Sword of Orion. It is in fact the brightest nebula in the sky.

The Orion Nebula

This glimpse into the heart of the Orion Nebula. This image shows an area a little over one light year across in the central regions of the nebula. The bright newborn cluster of stars to the lower right is the Trapezium. Image source: NASA.

Though not apparent to the naked eye, Orion contains a gigantic dark cloud of matter, the largest such cloud known in the Milky Way Galaxy. Within the Orion Molecular Cloud, new stars are forming, a process that creates a pocket or 'bubble' around the newly emerged stars.

The quadruple star known as the Trapezium is one of these young systems, thought to be little more than 100,000 years old. It started to form just within the edge of the cloud, and its bubble has burst through that edge, leaving us with an illuminated view of the cloud's interior: the Orion Nebula.

The nebula's reddish colouration betrays the predominance of ionised hydrogen in the parent cloud, but more complex molecules such as carbon monoxide have also been detected. Stellar formation in this region of space is still in progress, and infrared observation suggests that at least two new stars will shortly come into existence.

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