The desert planet, third planet of Canopus, and the sole source of the spice melange in the known universe. Called 'Dune' by its inhabitants, Arrakis is a world of extreme aridity where water is the most precious commodity. Its surface is dominated by vast sand seas patrolled by enormous sandworms. The planet passes from Harkonnen to Atreides control at the start of the saga, and its Fremen inhabitants prove to be among the most formidable fighters in the Imperium. Under Muad'Dib and later the God Emperor, Arrakis becomes the centre of human civilisation.