Astrology doesn't work.
Shocker, I know. I've written on this topic extensively, but of course astrologers send me email -- seriously -- saying how their flavor of magic works, or that I wasn't fair, or that if only I faced the right way and triantrilated my fibbertygibbet, astrology would be correct, despite my article very carefully showing that no matter how you slice it, astrology doesn't work.
Obviously, astrology's horse isn't quite dead yet, so beating it isn't such a bad idea. My friend Moriel Schottlender wrote up a nice dissection of astrology walking through the steps showing (despite many astrologers' claims) that gravity clearly is not the force behind astrology. She even includes math.
Of course, those of us in the reality-based Universe knew this, since when tested properly astrology fails tests devised even by astrologers themselves (see my article linked above). So there is no force behind astrology, except that of the human mind to fool itself. Because of that, we'll always be debunking bunk like this. I guess that's one thing astronomers and astrologers really do have in common: there will always be work for us.