The annosphere is a sundial that works without the sun. It shows you the time of day and the time of year as well. It keeps track of the changing seasons and models sunrise and sunset for each day, for any place on earth.
The annosphere has only two significant moving parts, neither of which moves very quickly. There is a disk in the center, which rotates once each day, and a ring surrounding it, which rotates once each year. From that, all the rest follows.