Orion nebula. Coloured composite infrared and visible light image of the Orion nebula M42. This emission nebula, a cloud of gas and dust in which starbirth takes place, is found in the constellation Orion, some 1500 light years from Earth. Glowing clouds of ionised hydrogen and sulphur gases are green, and cool clouds of polycyclic aromatic hydrocarbons are orange and red. The gases are ionised by radiation from the four young Trapezium stars at the core (centre left). The small orange dots are embryonic stars, growing as they accumulate dust and gas. M42's neighbour, the M43 nebula, can also be seen (pale blue, top left). Infrared data from the Spitzer Space Telescope, visible light data from the Hubble Space Telescope.