Astrology is a science of the effects of planetary movements on our lives. Astrology is based on astronomy, and astrologers need to know the correct positions of the planets at any given time, as well as the correct positions of the zodiacal fixed star signs in relation to any place on earth at any given time. Once the correct positions of the signs and planets are known, astrologers can construct charts representing these positions. And using his knowledge, the astrologer can study the charts and can make a wide range of conclusions about the moment the chart was cast for. Primarily, astrology is used to understand one's self, and our karma for this life.