In The Impossible Planet, the Doctor and Rose land on a base clinging to a planet orbiting, impossibly, a black hole. Now, the instinctual reaction when faced with a giant galaxy-eating hole in the sky is to run as far away as possible. But these people are there, where their homes sky sends some people mad. They flew down a tiny little gravity tunnel and built a base at the most dangerous point in the universe. Why? As the Doctor put it Because it was there. Were curious, were tenacious, and we go to find the thing that should not be found. If you built a big red button and painted a sign do not touch the paint wouldnt have time to dry. And if you put an impossible planet, the prison of unknowable evil, at the doorstep of a black hole, well go right in. Thats pretty cool. Its no wonder the Doctor thought it was awesome.