This morning, using a book about planets as a tool, I interviewed Benji about the Solar System. He has been particularly interested in planets for quite a while, so he’s learned more than your average preschooler about this (although how much he really understands is a matter of some uncertainty).

Me [Pointing to the Moon]: What’s this?
Benji: That’s the Moon.
Me: Is it a planet?
Benji: No, it a moon, it spins around the Earth [he spins himself, presumably to represent the Earth, with his hand twirling as the moon to demonstrate]
Me: Oh. What makes Earth a planet, then?
Benji: Moons go around planets [more spinning], planets go around moons.
Me: Planets go around moons? [Dang, we were doing so well!] Don’t planets go around the Sun?
Benji: Oh, yeah! Planets go around the Sun.
Me: What about the Sun? Is the Sun a planet?
Benji: No, the Sun is a big hot thing in the middle, that the planets go around. See, the yellow is hot and the blue is cold [indicates the picture on the page, where the Sun is shown on the left-hand side with a yellowish glow extending through the orbit of Mercury towards Venus, and then it fades into pale blue and then into dark indigo out around Pluto on the far right side]. This side of Mercury [towards the sun] is hot. This side cold. Venus and Mercury have no moons. Mercury too hot. Venus, the atmosphere catch any moons [?!]

Then, with no additional prompting, he added: Mercury, Venus, Earth, Mars all ROCK. THESE big planets, Jupiter and Saturn, GAS GIANTS. No rock, they all gas. These two is Uranus and Neptune, they ICE GIANTS, they have place to land [uses a tripod of fingers to indicate a space ship landing]. Uranus tipped over, Neptune reeeeeally far away and cold.
Me: Why is Uranus tipped over?
Benji: [long pause] I no know.
Me: Nobody knows, so that’s OK. If gas giants are all gas, are ice giants all ice?
Benji: Yes. [oops, some confusion about the composition of the ice giants!]
Me: That’s a lot of ice.
Benji: And Pluto have some little chunks of blue ice on it too.
Me: Do planets do anything for us?
Benji: One planet, Earth! It do lots for us.

That’s as far as our interview got, although Benji would willingly have kept discussing planets and the Solar System in great detail. Pretty fun stuff.