Astrology? Total horlix in my opinion but it was taken terribly seriously once upon a time. My research into early science frequently involves astrology and its detractors, so it is good to find that so many old texts are on the web. Not usually on academic sites but by the heirs to the astrological tradition. They still believe it works and have started using medieval and early modern texts to get back to basics.
Good sites on astrology including texts: Deborah Houlding's Skyscript and Robert Zoller's Medieval Astrology.