You think it’ll last forever, people and cars and concrete, but it won’t. One day it’s all gone. Even the sky. My planet’s gone. It’s dead. It burned like the Earth. It’s just rocks and dust before it’s time.

Doctor Who 1.02 - “The End of the World”
Rose: How long’s it got?
Doctor: About half an hour and then the planet gets roasted.
Rose: Is that why we’re here? I mean, is that what you do? Jump in at the last minute and save the Earth?
Doctor: I’m not saving it. Time’s up.
Rose: But what about the people?
Doctor: It’s empty. They’re all gone. No one left.
Rose: Just me, then.