You will never find a scientific explanation why astrology works. This is because science is 'smaller' than astrology. You can use science to point at results that seem to indicate that astrology works, this is possible.
But it's my belief that the WHY of astrology could only be explained by a larger knowledge, which we currently have forgotten.
Oh don't give me that.
Define Science:
1. The intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment.
Electromagnetic energy is too weak to explain it.
The first step in proving WHY it works is to prove that it does work. Without question. If you can prove that it does work... and I mean actually 100% prove it with very little margin of error, taking out most human interpretation to avoid the observer effect and cold reading... then you can worry about the why's and how's.
Right now, Astrologers are divided into two major categories. The ones who are scientifically minded, who know and want to apply the Scientific method to the study. And the ones who are spiritually minded and just accept things as they are.
The spiritually minded people are holding the study of "why" and "how" back. Don't get me wrong, they're great for figuring out the intricate details of what things mean... but they're still holding the advancement of the study back.
Religion is holding the study back because it's taboo.... omg, no one can predict the future. You're a false prophet, burn the witches.
Science is holding it back because... you honestly expect us to take it seriously? LOOK at most of the people who study it.
Astrology is placed in the wrong category, and it's attracting way too many people who give it a bad name. It needs people to sit down, take it seriously, and actually work on it. Work on the proofs, work on the "why" and "how".
As for the things that were linked in this thread, showing why Astrology works, or the work that people have done to prove it. I say, sorry... not good enough. Work harder, or you're doing it wrong. When the answer is found, Astrology will take its place among the serious sciences. Until then, the answers that people have come up with are wrong, or only partial. It will be figured out, it will be proven. But classifying it as a spiritual or religious thing is just as bad as giving up.