Episodes From the Early History of Astronomy [Paperback]

Phenomena in the heavens are of great importance to many, and much of the lore of astronomy and astrology dates back to the earliest days of civilisation. The astronomy of the ancients is thus of interest not only as history but also as the basis for much of what is known or believed about the heavens today. This book discusses important topics in Babylonian and Greek astronomy.The author does not attempt to give a general survey of early astronomy; rather, he chooses to present a few episodes and treats them in detail. However, first he provides the necessary astronomical background in his descriptive account of what you can see when you look at the sky with the naked eye, unblinkered by received knowledge, but with curiosity and wit.Chapter 1 deals with the arithmetical astronomy of ancient Mesopotamia where astronomy first was made an exact science.Next are treated Greek geometrical models for planetary motion, culminating in Ptolemy's equant models in his Almagest. Ptolemy does not assign them absolute size in this work, but, as is shown here, if we scale the models properly, they will yield good values, not only of the directions to the planets, but of the distances to them, as well. Thus one can immediately find the dimensions of the Copernican System from parameters in the Almagest - we have evidence that Copernicus did just that. Further, Islamic astronomers' modifications of Ptolemy's models by devices using only uniform circular motion are discussed, as are Copernicus's adoption of some of them. finally, it is made precise which bothersome problem was resolved by the heliocentric hypothesis, as it was by the Tychonic arrangement.Next, the Ptolemaic System, the first cosmological scheme to incorporate quantitative models, is described as Ptolemy himself did it in a recenlty recovered passage from his Planetary Hypotheses. Here he does assign absolute size to his models in order to fit them into the snugly nested spherical shells that made up his unilS(