I need to prove that astrology has no predictive power whatsoever!! How do you effectively tell an intelligent family member, who knows basic science, that astrology has no predictive power whatsoever, is a pseudoscience and worthless in predicting the future, without sounding partisan or offensive? How do you tell a person not to take every statement printed in an astrology books as a fact, and to search and try to find out if that statement has been independently and objectively tested? How do you tell a person that while astrology has no physical basis, that astronomy is real and so much more interesting, grander and awe inspiring? This is part rhetorical, and part dejected.