Almost everybody knows the concept of Zodiac. But there are others. And, AFAIK, even Zodiac classification is wrong for nowadays - since the classification of the people's Zodiac Sign was developed thousands years ago, when the stars were in a slightly different positions.
I don't really care about this stuff. But I want to know for sure, given the exact birth time and location, what star was over my head, if I looked straight up?
How can I calculate what star was above my head within a reasonable margin of error?
P.S. I don't mean any kind of software, that does all the job - I mean the algorithm, which includes the calculations (on the paper), and some related knowledge database about all known stars and their trajectories.