Happy Birthday, Severus

My beloved astrology book, (The Secret Language of Birthdays by Gary Goldschneider and Joost Elffers), has some interesting things to say about Snape's birthday. JKR has made some references to modeling the Houses after elements, so it wouldn't surprise me if she uses astrology in her character building.

There are some Book 6 spoilers below, if anyone's still worried about that.

( Capricorn - January 9 - The Day of Ambition )