There are many weaknesses with astrology. The first is its source of authority. The authority is the astrologer. If, however, everything is predetermined by the stars, how do the astrologists get out of the fatalistic course to observe the course. There are also different systems of astrology.
Westerners have a different way of reading the horoscope than, say, a Chinese astrologer does.
They have the same stars, but different interpretations. There are even differences of opinion among astrologers as to how many signs of the zodiac there are. Some contend for eight over the traditional twelve, while others contend for fourteen or twenty-four. It is very likely that one could go to two different astrologers the same day and be told two completely different destinies for their lives. Astrology is based upon faulty assumptions.