There's no tradition of scientists knocking down the Sunday school door, telling the preacher, That might not necessarily be true. That's never happened. There're no scientists picketing outside of churches.

Your center of mass is a place you cannot visit but you always carry with you. Like memories, it is part of life's baggage.

Math is the language of the universe. So the more equations you know, the more you can converse with the cosmos.

We can trace the elements. They were forged in the centers of high-mass stars that went unstable at the ends of their lives, they exploded, scattered their enriched contents across the galaxy, sprinkled into gas clouds that then collapsed and formed stars and planets and life.

When scientifically investigating the natural world, the only thing worse than a blind believer is a seeing denier.

If you want a nation to have space exploration ambitions, you've got to send humans.

We should not measure our space-faring era by where footprints have been laid.... We should measure our era by how many people take no notice at all. A legacy rises to become culture only when its elements are so common that they no longer attract comment.