Astrology is definitely a science. Of course, it depends on your definition what is a science but the dictionary gives several meanings.
If you read Shyamasundara dasa's webpage http://www.shyamasundaradasa.com/ then you will find that Vedic Astrology is not only jataka or birth horoscope. There are other disciplines like muhurta (auspicious times), prasna (questions), nimitta (omens), ganita (mathematics) and gola (astronomy). All is very subtly and also not very systematically studied lately, thus many things will be very unclear and controversial.
Regarding to dasa's question: even a few minutes difference in birth time can give very different results. And geographical locations also is important.
I don't know much about Vedic astrology myself but it seems that as other Vedic sciences its primary purpose is to awaken devotion to the Personality of Godhead. Materialistic and attached people are always anxious about their future. If they approach an astrologer who gives them correct predictions they will develop faith in Vedic disciplines and consequently learn that it all is predetermined by the movements of the planets. In other words, their karma gives them good and bad results. And that the only remedy is the devotion to Krishna.
I personally don't think we should mix ideas about quantum mechanics in trying to explain subtly subjects like Astrology. This will only lead to unprovable speculations and ridicule from real scientists. And empirically I don't see a way how planets, even if they have a conciousness, could be determining our fate. But I believe that there is a higher reality and planets are only gross expressions that our senses can perceive.
karunanidhi
