I never seriously 'get' the astrology thing either. However, tides moves oceans and the moon is partly responsible. The planets must affect us, in what way is a mystery to me.
Gravity is one way, but then we're delving into astronomy and physics rather than astrology. I have yet to see divination be utilized in a significant and consistent manner. If anyone is interested in Astrology there is one, James A. Eshelman, who practically creams in his pants when the topic is brought up. A short Google search should suffice to find him.