Light in the darkness
When we try to set out the history of astronomy, we tend to emphasise two great periods of discovery, with a long dark space in between. We think of the ancient Greeks such as Hipparchus and Aristarchus, building on the work of the Babylonians and culminating in the venerated Ptolemy. A few centuries after him, Rome fell, and the barbarians took over. We pick up the trail more than a millennium later, with the
