The Horoscope
Western astrology is based mainly upon the construction of a horoscope, which is a map or chart of the heavens at a particular moment. The moment chosen is the beginning of the existence of the subject of the horoscope, as it is believed that the subject will carry with it the pattern of the heavens from that moment throughout its life. The most common form of horoscope is the natal chart based on the moment of a person's birth; though in theory a horoscope can be drawn up for the beginning of anything, from a business enterprise to the foundation of a nation state.
Read more about this topic: Western Astrology