William R. Shea is Galileo Professor of the History of Science at the University of Padua, Italy (where Galileo himself held the Chair in Mathematics). He has written several books on Galileo and the Scientific Revolution. The latest, written with the Spanish scholar Mariano Artigas, are Galileo in Rome- The Rise and Fall of a Troublesome Genius (2003) and Galileo Observed- Science and the Politics of Belief (2006). Dava Sobel is an award-winning and best-selling writer of books on the history of science. Her works include Longitude (1995), Galileo's Daughter (1999) and The Planets (2005).