I pointed out the incredibly beautiful crescent moon to Penny, and she told me that while she was riding in the car and walking around, the moon followed her.
"Do you know why the moon follows you?", she asked me. I can't turn down an opening like that, so I asked her to tell me all about it.
"Because gravity. The moon has no gravity in space, so it follows you and goes and the sun is in space too with no gravity. Also Jupiter."
She already has a better handle on this than a lot of grownups I could mention.