'I didn't say planet, I said world. The worlds are separate. Each one has its own sun, its own moon. And when they die, their light goes out. Stars, at least where I come from, aren't... balls of plasma. They're the light and life shining from a world's heart, through the darkness that separates the worlds. And the heartless snuff that light out." It's not necessarily common knowledge, but he's well aware of it, having been to many a world in the past.