From Hipparchus and Ptolemy in the ancient world through Copernicus andBrahe in the sixteenth century astronomers had used geometrical models to givea kinematic... » 

From Hipparchus and Ptolemy in the ancient world through Copernicus andBrahe in the sixteenth century astronomers had used geometrical models to givea kinematic account of the movements of the sun moon and planets. JohannesKepler revolutionized this most ancient of sciences by being the first tounderstand astronomy as a part of physics. By closely and clearly analyzing thetexts of Keplers great astronomical works in particular the Astronomia novaof 1609 Bruce Stephenson demonstrates the importance of Keplers physicalprinciplesprinciples now known to be incorrectin the creation of hisfirst two laws of planetary motion. «