Astrology is a failed science. The fact that people have been using astrological divination for thousands of years does not mean it works. The notion that the stars and planets affect your personality or events makes no scientific sense. Known physical effects of these bodies are negligible. The choice of the stars in constellations are random both in visibility from the earth when you include the southern sky and in their distances from earth and each other.
Horoscopes cast by astrologers are usually quite vague.
If you randomly assign horoscopes to people without telling them, they find the horoscopes describe them quite well and offer good advice. Astrologers explain that twins or people born on the same day in the same geographic area may not have the same character or future because the time of birth is not exactly the same. If the final outcome varies so widely with the exact time of birth, the theory is essentially useless. Sources George O. Abell and Barry Singer, eds. Online Edition of Grolier's Academic American Encyclopedia.