For Clell65619 -- Because Brad hasn't yet figured out TJ, while all the rest (including Luann) have.
For all, what TJ's drawn isn't a planetarium (he spelled it wrong also) but a small observatory.
Planetarium?!? He should say yes just for that! However, that's the wrong place for it; they should move it over to the garage side, at level 2 or they won't see very much... unless I'm mistaken about the heavenly bodies they are aiming for...
