Apple Motion 3 - Manual (Page 491)

Chapter 5 Using Behaviors 491
The Orbit Around behavior is applied to the group of circles (“circles 1”) in the project.
The center circle in the center of the Canvas is in a separate group from the rest of the
layers.
When the Orbit Around behavior is first applied, no animation occurs. This is because
you must specify the layer that the group will orbit around.
5 Drag an object, in this case the “center circle” layer, from the Layers tab and drop it in
the Object well of the Orbit Around HUD or Inspector.
This object becomes the target object around which the other objects orbit.
You can alternately drag an object in the Layers tab onto the Orbit Around behavior.