The Orion Nebula M42 is the brightest diffuse nebula in the sky and one of the brightest deepsky objects overall. Shining with the brightness of a star of 4th magnitude, it visible to the naked eye under moderately good conditions. It is also a big object in the sky, extending to over 1 degree in diameter, thus covering more than four times the area of the Full Moon.

The Orion Nebula is located at a distance of about 1,600 (or perhaps 1,500) light-years.At the end of the Fish's Mouth there's a cluster of newly formed stars, called the "Trapezium cluster". The Trapezium Cluster is among the very youngest (open) clusters known, with new stars still forming in this region.

It is very easy to find the Orion Nebula, as it surrounds the Theta Orionis multiple star or cluster, seen to the naked eye in the middle of the sword of Orion. Under fairly good conditions, the nebula itself can be glimpsed with the naked eye as a faint nebulosity around this star.