The dome rotate bearing and drive. The bearing has a 12" diameter with a wooden disk mounted either side. The motor is attached to the top disk on a spring loaded pivot. This keeps a drive wheel, mounted on the axis of the motor, against the fixed side of the bearing.

This is just running with 12V supplied to the motor, there is no controller. The finished unit will be position controlled using a rotary pot as feedback.

P.S I know the dome isn't spinning completely true. It hasn't been aligned yet.