



Stand there on the brow of the hill in Greenwich Park, your head still full of planets spinning on their computer-generated orbits, with the National Maritime Museum, the curve of the river, Canary Wharf and all the city stretched out beneath you, and the vista seems to roll inexorably east towards the curtain of night. Stumbling out from beneath the 45-tonne bronze cone of London's planetarium, unsteady from a virtual voyage through the solar system and beyond, you can picture the earth turning beneath your feet.
