The Seasons tellurium (a tellurium shows the movements of planetary objects) is used to show how seasons are formed. In the center of the exhibit is the sun, which shines a bright focused beam of LED light at the earth that rotates around the center of the exhibit. Power is transferred into the rotating shaft using quality slip rings, and transferred through the center of the shaft towards the earth. Another slip ring on the end of the rotating shaft transfers power into the earth globe, where we have a very small high quality servo motor and servo controller that rotates the earth around its axis.

We were not satisfied with the quality and mounting methods of commercially available globes, so we decided to make the globe in house. The globe itself was designed in 3D studio max, complete with a bayonet coupling in the bottom that mates directly with a custom coupling we built for the motor. The motor design was implemented in the computer, and "test fitted" in the virtual world with the coupler in the globe to make sure that it would fit. The top of the globe was designed to "peel off" and has clips that were "printed" in ABS plastic as part of the globe assembly.

At the top of the mechanism we use a quality drive motor and gears for the rotation, and there is a hard-coupled absolute encoder that gives the video server a very accurate position for the mechanism; this positional signal is then coupled to the video server which in turn ensures that the video is delivered with frame-accuracy so that we know that we're showing summer images during summer, and winter images in winter to an accuracy of 1/10th of a degree of rotation.