Precession of the Equidots
This unusual spinning top consists of two wooden balls glued together. The spinning top is painted yellow, but there is a black dot on each of the wooden balls. Whe you spin the top, something unususal happens. Because the top rotates about the point where the two wooden balls meet, but also rotates around the axis that runs through the whole top, you see a black dot appear, and slowly rotate in a circle, as a result of the two simultaneous rotations.