The idea that God resides in the unknown is what philosophers call the God of the gaps. And we have this thing called science, which marches on and makes discoveries in those gaps, ultimately closing gaps.

The first colony on Mars is not going to be built by a private company. How are you going to make money? You're not.

Everyone has all different experiences in school. I just know that throughout my life, at no time did any teacher ever point to me and say, hey. He'll go far.

We still refer to sunrise, sunset. That only has meaning if you think that Earth is in the center of things, and everything is moving around us. So even though we know intellectually Earth goes around the sun, the language is still pre-Copernican, as we would call it.

Eventually, the Sun will swell to occupy the entire sky as its expansion subsumes the orbit of earth. Earth's surface temperature will rise until it matches the 3,000-degree rarified outer layers of the expanded Sun.... But not to worry. We will surely go extinct for some other reason long before this scenario unfolds.

Everything we do understand about the universe - the periodic table of elements, Einstein's laws, Newton's laws, all of chemistry, all of biology - that's 4 percent of the universe. We got to the moon on the 4 percent we do understand. We landed on Mars on the 4 percent we do understand. So the day we crack the nut of the rest of that 95 percent... Oh my gosh.

The chunks of comet Shoemaker-Levy 9 were so large, and were moving so fast, that each hit Jupiter with at least the equivalent energy of the dinosaur-killing collision between Earth and an asteroid 65 million years ago. Whatever damage Jupiter sustained, one thing is for sure: it's got no dinosaurs left.