Does Celtic Astrology Offer A New Approach? Astrology is the study of astronomical bodies and their relationship to people on the earth. It is a form of divination that has been practiced for centuries by a multitude of cultures, all of which have used this pseudoscience to predict and decide on the best course of action for each person's life. Depending upon the culture that you are in, astrology can be very different. In this article we will look at the differences between Western and Celtic astrology. What Is Western Astrology? Western astrology is a form of astrology that originated in the second century, based upon Ptolemy's Tetrabiblos.