The worst thing that ever happened to America was the 19th Amendment.

The caricature of science is that we hold tight to the theories we have, and shun challenges to them. That's just not true. In fact, we hold our highest rewards for those scientists who can prove others wrong. And by the way, they are famous in their own lifetimes. We don't wait until they're dead.

Intelligent design is a philosophy of ignorance.

I believe that the manned space program can engage the public by advancing the space frontier. Every next mission takes you farther out in space than you were before, either technologically or in terms of distance.

The iron from that meteorite and the iron from your blood have common origin in the core of a star.

When you're a hammer (as the saying goes), all your problems look like nails. If you're a meteorite expert pondering the sudden extinction of boatloads of species, you'll want to say an impact did it. If you're an igneous petrologist, volcanoes did it. If you're into spaceborne bioclouds, an interstellar virus did it. If you're a hypernova expert, gamma rays did it.

There are two kinds of comments that I get. One is, oh, you're such a natural up there, and the other one is, you're working hard up there. And the ones who say I'm working hard are teachers, they're the educators; they're the people who are the performers. It's a huge investment of my psycho-emotional energy to pull that off and to make it look smooth.