My popularity does not derive from me pandering to people. People came to me. I don't tell anyone to follow me on Twitter. I don't tell people to like my Facebook page. I don't tell people to fill the venue. I'm offered to people, and then people come.

Space in general gave us GPS - that's not specifically NASA, but it's investments in space.

To achieve this density of a neutron star at home, just cram a herd of 50 million elephants into the volume of a thimble.

Going into orbit around Earth - where the space station is today, and where the space shuttles and John Glenn and all those folks go-that's three-eighths of an inch above a schoolroom globe, just FYI. That's not very far from Earth. Yes, you are off Earth, but you're not really going anywhere yet. The moon was the only real destination.

I object to religion in science classrooms not because it's religion but because it's not science.

Italy valued cathedrals while Spain valued explorers. So worldwide, five times as many people speak Spanish than Italian.

I don't have specific television ambitions in the sense that I remain fundamentally and academic, and so, my innermost ambitions are what's the next discovery I can make; that's in my direct center.