Apple Motion 4 - Manual (Page 525)

You create animation using the Orbit Around behavior by specifying a target object that
other objects circle around. You set the target object by dragging the object to the Object
well in the Orbit Around Behaviors tab.
To use the Orbit Around behavior
1 Using the result of the previous example, delete the Edge Collision and Gravity behaviors
from the project.
2 In the Layers tab, click the Add button (+) to create a new group, then rename the group
“Center.”
3 Option-drag the one of the stars to the new group.
A copy of the layer is added to the group.
4 Rename the copied star “center star,” then position the star in the center of the Canvas.
5 Apply the Orbit Around behavior to the Stars group.
The Orbit Around behavior is applied to the group of stars (“Stars”) in the project. The
center star in the center of the Canvas is in a separate group from the rest of the layers.
525 Chapter 9 Using Behaviors