[Letiel]

Good heavens no. Granted the sky IS changing. There's a black hole in Cygnus eating the center star and everything but this "new" constellation has been around awhile.

People were just so content with the evenness of 12 to 12 months. This system set up for thousands of years didn't need to change. In truth the sun's path along the ecliptic isn't in each constellation equally so following a schedule is stupid. To know your exact sign you would have to consult star charts of the date.