Let's pretend that I'm Galileo

Here's a bit of the conversation that Richard and I overheard on the drive back from Memphis this weekend:

Hannah: When it gets night it's not 'cause the sun is disappearing, it's 'cause the earth flips over.
Sam: Nuh-uh.
Hannah: Yes, because the world is spinning all around.
Sam: NUH-UH, Hannah. If the world flipped over then all the cars would flip over, too.  And we would flip over and then we would fall off into outer space.
Hannah:  Oh, no no no no.  You see, there's a big bubble all around the world and it is keeping everything stuck inside.
Sam: Oh, I get it.  And when a rocket goes into the sky it pops a hole in the bubble and then when it comes back it fixes the hole and then it lands.  How does it fix the hole?
Hannah:  I don't know.  Maybe it's 'cause there's two kinds of air.  Mom told me about that.
Sam: Yeah.  Normal air and fresh air.