La Silla Observatory at night, Chile. At centre is the Danish 1.54-metre telescope. Arching over the telescope is the Milky Way galaxy. Also visible in the sky are both the Large and Small Magellanic Clouds, the constellations of Orion (The Hunter) and the Southern Cross, and the glare of distant settlements, all of which create vibrant bursts and flashes of colour across the frame. Towards the distant horizon, hues of red and green light up the sky, these colours are produced by a phenomenon called airglow.