Alien planets and Orion nebula. Artwork of alien planets against a background of the Orion nebula (M42 & M43). Planets have been discovered drifting in the Orion nebula. M43 (NGC 1982, lower right) is a smaller part of the nebula, separated from M42 (NGC 1976, main image) 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 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.