This essay by Copernicus (1473-1543), revolutionized the way we look at the earth's placement in the universe, and paved the way for many great scientists, including Galileo and Isaac Newton, whose theories stemmed from this model. Featuring a biography of Copernicus and an accessible, enlightening introduction, both written by the renowned physicist Stephen Hawking, On the Revolution of Heavenly Spheres provides a fascinating look at the theories which shaped our modern understanding of astronomy and physics.