If you get asteroids about a kilometer in size, those are large enough and carry enough energy into our system to disrupt transportation, communication, the food chains, and that can be a really bad day on Earth.

We should not measure our space-faring era by where footprints have been laid.... We should measure our era by how many people take no notice at all. A legacy rises to become culture only when its elements are so common that they no longer attract comment.

People put clips of me up. There are quotes from me. I've written books, of course. I'm on Twitter. There are dozens of ways to consume my offerings, and a lecture in a large venue is really only just one of them. So I have no concerns about how much access people would have to me no matter what is the capacity of your pocketbook.

I look up at the night sky, and I know that, yes, we are part of this Universe, we are in this Universe, but perhaps more important than both of those facts is that the Universe is in us. When I reflect on that fact, I look up — many people feel small, because they’re small and the Universe is big, but I feel big, because my atoms came from those stars.

What would aliens say when told earthlings shift clocks twice a year to fool themselves into thinking there's more sunlight?

You say you're worried about kids? I'm not worried about kids, I'm worried about grown ups... Children are not the problem here... We spend the first year of their lives teaching them how to walk and talk, and the rest of their lives telling them to shut up and sit down.

God displayed a sense of humor when he configured the region between our legs an entertainment complex built around a sewage system.