At the Air and Space Museum today (a visit which was almost ruined when both kids had an epic meltdown upon learning that no, they would not be allowed to climb into the Space Shuttle. Because standing fifteen feet away from the SPACE SHUTTLE isn't an amazing enough experience).
"Mama, why do astronauts wear masks?"
"Because there is no air in space and their space suit helps them breathe. The mask keeps the air from getting out."
"Why there no air in space?"
"Because our atmosphere is held close to our planet by gravity. After you get too high, there isn't enough air to breathe. Then you are in space."
"But WHY don't the astronauts want the air to get out of their suit, Mama?!"
"Why that plane has teeth on it?"
"Because they wanted it to look tough."
"Because they wanted to intimidate the other guy."
"Because they were fighting."
"Why were they fighting?"
"Because sometimes countries disagree and then they have a big fight to see who wins."
Bystander: "Good luck with that one!"
"Why can astronauts fly?"
"They don't fly, sweetie, they're weightless!"
"Why are they weightless?"
"Um, because there is a balance of forces that is pulling on them and they're sort of actually falling around the earth...uhhhh..."
"But WHY can astronauts FLY, MAMA?!!"
"Why is it called an air PLANE?"
"Because it flies in the air?"
"But why air PLANE?!!!"
"Because a plane is a big flat surface, like a wing.
"But why it it AIR plane?!!"
"Who wants to go to Sonic?"