EBOOK Ballet of the Planets:A Mathematician's Musings on the Elegance of Planetary Motion

The Ballet of the Planets unravels the beautiful mystery of planetary motion,        revealing how our understanding of astronomy evolved from Archimedes and Ptolemy to        Copernicus, Kepler, and Newton. Mathematician Donald Benson shows that ancient        theories of planetary motion were based on the assumptions that the Earth was the        center of the universe and the planets moved in a uniform circular motion. Since        ancient astronomers noted that occasionally a planet would exhibit retrograde        motion--would seem to reverse its direction and move briefly westward--they        concluded that the planets moved in epicyclic curves, circles with smaller interior        loops, similar to the patterns of a child's Spirograph. With the coming of the        Copernican revolution, the retrograde motion was seen to be apparent rather than        real, leading to the idea that the planets moved in ellipses. This laid the ground        for Newton's great achievement--integrating the concepts of astronomy and        mechanics--which revealed not only how the planets moved, but also why. Throughout,        Benson focuses on naked-eye astronomy, which makes it easy for the novice to grasp        the work of these pioneers of astronomy.