One of the most obvious things about the night sky is the moon, especially the full moon. The full moon transforms not only the sky, but the earth, creating a dimmer, second kind of day, casting long shadows, and providing some guidance to those who find themselves outdoors.

Certainly, it is one of the things that children first notice about the sky. They can point to the moon, ask what it is, stare at it in wonder.

And then, a few days later, the child can wonder - where did it go?

The sun, after all, travels in a more orderly fashion. The sun rises and the sun sets. It begins and ends the day. It's not day without the sun. But it can be night without the moon. Sometimes it's the most obvious thing in the night sky and sometimes it's not there at all.

That's part of what Luke intends …