Summary: Melvyn Bragg and his guests discuss the ancient Greek astronomer and mathematician Ptolemy, and consider how and why his geocentric theory of the universe held sway for more than a thousand years. It was not until 1543, and Copernicus's heliocentric theory of the world, that the Ptolemaic model was finally challenged. But how and why did Ptolemy's system survive for so long? Melvyn Bragg is joined by Liba Taub of Cambridge University, Jim Bennett of the Museum of the History of Science at the University of Oxford, and Charles Burnett of the University of London.
