Last night, as we were reading a book about the solar system:
DD (from the book): The sun has another 5 billion years left to burn.
The Boy: Daddy, will all the people be gone by then?
DD: Probably.
TB: Well then who will watch the earth?
DD: God will.
TB: Will God make new people to watch the earth?
(pause)
DD: I don't know. That's up to God.
Later in the same book....
TB: What is water made of?
DD: Hydrogen and oxygen.
TB: What are those?
DD: Gases.
TB: Oh. Is it easy to make water?
DD: Well...
TB: It sounds easy, but I think it would be hard. Gases are hard to catch. They're like air!
Still later in the same book...
DD: Jupiter is a gas giant.
TB: Like Daddy! (roars with laughter)
I'm just glad he doesn't know enough yet to make Uranus jokes.