This book shows readers how to calculate the orbit of Mars, based on their own observations and using observations made by the author. The historical, observational, and analytical aspects of the project to measure the orbit of Mars are all combined in this one book! Determining the orbit of Mars is particularly important, as originally solving this problem required the founding of modern science. Clark discusses how people came to believe in the Newtonian model of the Solar System, works through the mathematical basis for the theory of gravity, and shows how Newton ruled out the possibility of alternative theories. Readers also learn how it became possible to accurately measure the positions of Mars from a moving, spinning platform—the Earth. This mid-level observational challenge is well within reach of most serious amateur astronomers. For the observations, only a telescope with auto-guiding capability and the ability to mount a digital single lens reflex (DSLR) camera is required. For the calculations, it is assumed that the reader has a science, engineering, or mathematics background and is familiar with calculus, vectors, and trigonometry.