Ever since early stargazers discovered that some heavenly bodies wandered among the others, people have been fascinated by the planets. Kepler calculated their orbits from naked-eye observations; Galileo's telescope made it possible to discern their markings; now observations from spacecraft provide electronically enhanced images that bring these distant worlds even closer. In Worlds in the Sky, William Sheehan gives us a history of this long fascination, weaving together scientific history, anecdotes surrounding planetary discoveries, and the personal reflections of an incurable amateur astronomer. He describes how we arrived at our current understanding of the Moon and the planets and shows how certain individuals in history shaped the world's knowledge about the Solar System. Placing historical observations in the context of recent discoveries, Sheehan questions whether these telescopic glimpses were revelations or more deceptions. By reflecting on the mental processes of early astronomers, he provides not only a fascinating account of scientific discovery but also a tribute to those who, long before Voyager, relied on their own powers of observation to travel to worlds in the sky.