Not wasting any water bottles is good. Not leaving the lights on is good. Turning the thermostat down in the winter, up in the summer, is good. But the best thing any of us in the developed world, especially in the United States, can be doing is talking about it.

Burning carbon-based substances like oil, gas, and especially coal, produces billions of tons of extra carbon dioxide each year. Methane gas from cows and pigs and other animals on our large farms ends up in the atmosphere as well, trapping more of the sun's energy as heat.

When we explore the cosmos, we come to believe and prove that we can solve problems that have never been solved. It brings out the best in us. Space exploration imbues everyone with an optimistic view of the future.

There's nothing I believe in more strongly than getting young people interested in science and engineering, for a better tomorrow, for all humankind.

Humor is everywhere in that there's irony in just about anything a human does.

My father was a very good Boy Scout. He was very skilled with knots, and he showed me how to tie a bow tie.

I meet so many people who are intimidated by arithmetic.