Some people try to explain it by resorting to the arguments of cosmic/electromagnetic waves and energy etc. They say that the bio-magnetic cells in human bodies respond to the electromagnetic waves of planets. Well, it sounds interesting because it uses the technical terms we are familiar with - man, after all, tends to explain new phenomena in old technical terms, but it is not "technical terms" that makes something "scientific", it is "logic" that does it. Sadly, these arguments lack logic. They merely make you think,"well, that's possible." They don't go beyond that.
As far as I am concerned, there are some statistical correlations between planetary movements and world events, that are extremely interesting. I will just work on refining my understanding of the correlations and modeling them as precisely as possible. I am not bothered about why those correlations work. I hope that it will be known to mankind in foreseeable future. Even if it's not known, it shouldn't stop the work on modelling those correlations.
After all, science is based on some fundamental observations that seem to hold true in practice (e.g., F=MA (Newton's first law)). In science, we have some statistical observations that seem to hold in practice and then some theories (and "technical terms") evolving from these fundamental observations. It is possible that astrology cannot be explained in terms of known theories - it is conceivable that astrology consists of a new set of fundamental statistical observations.