"Were you doing a lot of amateur astronomy while you were on Earth?" Thor can't imagine that he had much time for it, but then again, it felt like he didn't know his brother nearly as well in the last ten years. Or maybe he didn't really know Loki that well before then, but just hadn't been aware of it at the time. He'd been blindsighted by Loki's betrayal. Was there some slow buildup he had been blind to, some signs he should have caught before then? Thor's not sure.