Award-winners Mary and John Gribbin unravel the history of modern astronomy. How far is it to the edge of the Universe? It is less than eighty years since astronomers began to realise that even the distances to the stars are tiny steps on a truly cosmic scale, and that the Milky Way Galaxy in which we live is just one island in an immense ocean of space. John and Mary Gribbin tell the story of how the cosmic distance scale was measured, the personalities involved and the increasingly sophisticated instruments they used. Astronomers can now study light from objects so distant that it has taken ten billion years on its journey across space to us, travelling all the time at a speed of 300,000 kilometres per second: that's how far up is!