There are no articles any more that dream about the cities of tomorrow.

People say, oh we just need charismatic leaders to continue on to Mars. Now we've gone to the moon, of course Mars is next. No. Mars was never, of course, next. It is next if you think we went to the moon because we're explorers, but if you know we went to the moon because we were at war then we're never going to Mars. There's no military reason to do it, to justify the expenditure.

I think science has a better story to tell than anyone else has been able to tell and that's because it's based on the rigorous winnowing that science and scientists are always doing in order to find out what's really happening. I think it's really good to encourage generally our ability to tell stories and that's a great skill that we come by naturally, so I'm excited about that.

If Neptune were analogized with a Chevy Impala in mass, then how big is pluto compared to that? Pluto would be a matchbox car sitting on the curb.

There's an old saying in the space community: 'If God wanted us to be a spacefaring species, he would have given us a moon'.

With no gravitational force to work against, your body not only doesn't need the same amount of muscle and bone, it starts breaking them down. As on Earth, so in space: use it or lose it. And exercise may not solve the problem.

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.