Rose: So when it says guests, does that mean people?
The Doctor: Depends what you mean by people.
Rose: I mean people. What do you mean?
The Doctor: Aliens.
Rose: What are they doing on board this spaceship? What's it all for?
The Doctor: It's not really a spaceship, more like an observation deck. The great and the good are gathering to watch the planet burn.
Rose: What for?
The Doctor: Fun. Mind you, when I say "the great and the good," what I mean is the rich.