Revealers of the universe

Dava Sobel, the biographer of Copernicus and Galileo, tells us about the men whose painstaking work changed our understanding of Earth's place in the universe.Our theme today is the early history of astronomy. Could you tell us what century we are talking about here and what were the commonly held beliefs at the time?We begin in the mid-16th century and go to the early 17th century. This was a