In the 1520s a Polish cleric named Nicolaus Copernicus developed a revolutionary theory which placed the Sun, not the Earth, at the centre of our universe. The secret existence of this manuscript tantalised scientists everywhere in Europe. Then in 1539 a young German mathematician, Rheticus, travelled to meet Copernicus in the hope of setting eyes on it. Dava Sobel tells the story of a new concept of the heavens, and how Rheticus persuaded the cautious Copernicus to allow him to take the precious but dangerous manuscript out into a world that it would change for ever. In her compelling style, Dava Sobel chronicles the history of the Copernican Revolution, relating the story of astronomy from Aristotle to the Middle Ages. And as she achieved with her international bestsellers Longitude and Galileo's Daughter, in A More Perfect Heaven, Sobel expands the bounds of popular science writing, giving us an unforgettable portrait of a major step forward in the human knowledge of our universe.