Astronomy and astrology: once indistinguishable, now clearly separate

This Chapter 3 takes a closer look at how astrology and astronomy, once indistinguishable, were deemed capable of predicting future events or the future of a human life. The two disciplines emerged in remote antiquity, most notably in Mesopotamia but also in ancient Egypt. By observing celestial phenomena such as the paths of planets and stars, it was believed that one could foretell future events both in human societies and in individual lives. The disciplines spread to the Greek world in later centuries in the form of horoscopes predicting the fate of a given person. However, the scientific revolution that took hold in the sixteenth century introduced a clear distinction between astrology as a divination art and astronomy as a science describing the movements of celestial bodies. Astronomy became a leading science, achieving major discoveries such as those of Kepler and Newton, whereas astrology was increasingly rejected. Yet, in the twentieth century and especially since the 1950s, there have been ever more attempts at a scientific demonstration of the validity or invalidity of astrology, and we examine their findings. We also try to identify the reasons why astrology, despite its rejection on scientific grounds, retains a strong worldwide appeal.