"Well, you'd have to take some precautions I imagine. And the sky might be red. But I'm sure people born under two suns, they can figure it out. They've got to be bright." The Doctor raised an eyebrow, at least entertaining himself here. "And if it is too hot, if it's not nice enough to stay there forever, maybe that'd be a reason to find ways to visit other places. Ships that can sail through the sky, all the way to whatever star catches your fancy, just to see how beautiful it might be up close."