Historically, Astrology is the fore-runner of modern astronomy, cosmology, and even, in some aspects, modern oceanography. (Galileo could not countenance the idea that the Moon could influence the tides on Earth.) Modern astronomers predict sun spots and solar winds by analyzing planetary patterns as seen from the Sun.
Just as modern astronomy is a far cry from the observations and theories of Ptolemy and Copernicus, so is modern Western astrology a vastly different set of concepts than what is read in the average newspaper. While Western astrology has its antecedents in more than three thousand years of empirical observations, its more recent basis is firmly psychological rather than empirically predictive. The modern Western astrologer studies Jung, Moreno, Carl Rogers and other psychological theorists as well as the mathematics of planetary positions.
The new Western astrologer uses Jung's concepts of archetypes to explain and illuminate the combinations and contradictions found in an individual's psychological make-up. The natal chart - the map of the planetary positions at the time of birth as seen from Earth - is seen as a psychological map of the individual. The planets and constellations are no longer seen as a direct cause of events affecting the individual, but rather as a reflection of a deeper set of harmonic cycles inherent in the Universe.
Some books on the subject: Western and Celtic Astrology
Some other sites: Astrology Links