Orion nebula. Artwork of the Orion nebula (M42 & M43). M43 (NGC 1982, lower right) is a smaller part of the nebula, separated from M42 (NGC 1976) by a dark band of dust. The Orion nebula is a huge cloud of gas and dust which glows due to the ionisation of the hydrogen it contains by ultraviolet radiation from hot young stars within it. These stars form a cluster known as the Trapezium, contained within M42. The Orion nebula is the nearest large emission nebula (or HII region) to Earth, lying 1500 light years away in the constellation Orion.