Here the pendulum at the North Pole is started swinging along the left-right

axis, represented by the red line. Note the yellow handle of the tool in the

upper right hand corner of the frame. This will serve as a reference marker.

The entire model, including the earth and pendulum is slowly rotated in a

counterclockwise direction. The time on the screen roughly indicated how

far the model earth has rotated, with 24 hours corresponding to 360 degrees.

As the model earth rotates, notice how the pendulum no longer is swinging

along the red starting line. The direction of the swing is steadily shifting in

the clockwise direction with respect to the earth's surface. This shift is

called precession. After a full rotation, as seen by the yellow handle

appearing again in the upper right hand corner, the pendulum is

swinging again along the starting line.