Great Orion Nebula. Composite infrared image of the Great Orion Nebula, also known as Orion's Sword. This emission nebula is 1500 light years from the Earth and is the nearest large region of star formation. Infrared can peer through the dense dust that obscures millions of stars at visible wavelengths. The nebula is made up of hydrogen interstellar gas, which is ionised and lit up be stars within it. This image was made as part of the Two Micron All Sky Survey (2MASS) project using ground-based telescopes in the USA and in Chile. The project began in 1997 with the aim of surveying the entire sky using near- infrared technology.