Measuring the Universe: The Historical Quest to Quantify Space, Kitty Ferguson, Headline Book Publishing, ISBN 0 7472 2132 4, hardback, 306 pp., £14.99.

Our knowledge of the size of the universe has increased exponentially over the last century, and the story of changing conceptions of its size are as suitable a starting point for a history of astronomy as are the developing models of is structure. Fresno’s well-written text takes a familiar path from Hipparchus to Hipparcos via Aristarchus, Copernicus and Edwin Hubble. The last hundred years of discovery should breed caution, and our current knowledge may seem primitive when another century has passed. Ferguson concludes, citing Herman Bondi, that ‘our scientific knowledge is an island - and Island of What We Know...Every time we add to the island, the coastline - the line where we run up against the Unknown - grows longer. There are more and more locations where we encounter what we don’t know’ (p 294).