Where did the moon go?

Every day Gene and I are amazed at how many words Andrew knows. And how he puts words together to form sentences. Today, on the way home, the moon was in the sky. Andrew said "Mommy, moon in air!" I said "Yes, it is the moon." When we'd go around a curve or turn, the moon would go behind us. Andrew said "Mommy, where'd moon go?" Then when the moon would come back where he could see it, he'd say "There moon is!"