Long description

This figure contains two rectangles. The one at the top is labelled ‘the interface of the orrery: moving spheres that represent the sun and the planets’. The one at the bottom is labelled ‘the hidden/encapsulated mechanism that drives the movement of the spheres’. An arrow labelled ‘hides detail from’ goes up from the bottom rectangle to the top rectangle. Another arrow, labelled ‘depends on’, goes down from the top rectangle to the bottom rectangle.