By the way: Welcome to LessWrong! Feel free to post an introduction of yourself! If you want to get a good head-start on the kind of thing we do here, "What Do We Mean By Rationality?" is a good start, and if you're ever looking for other material, you can browse the sequences and the top-rated posts to find a lot of good essays.

On this specific issue, ata has the most relevant link, but I would add a couple other points:

1. Just because you could, in theory, be convinced of astrology at some point doesn't mean you have to be agnostic now - you can be quite strongly convinced of its incorrectness and still accept correction should some ever come to your attention.

2. If you are actually quite skeptical of astrology - if you believe it to be strongly contradicted by the evidence - this is one of the places where we would hope you would say so. Humility is a virtue when it makes you careful, not when it is attire you wear to affirm your open-mindedness.

Please keep posting, by the way - your remark on the externalities of nuclear power was a good one, and I would like to hear your thoughts on other occasions.