Hard to find anything lovelier than a tree. They grow at right angles to a tangent of the nominal sphere of the Earth.

If you meet somebody who says he or she has never dreamed of flying, I don't believe you. I mean, they're lying.

As my old professor Carl Sagan said so often, 'When you’re in love, you want to tell the world.’ And I base my beliefs on the information and the process that we call science. It fills me with joy to make discoveries every day of things I’ve never seen before. It fills me with joy to know that we can pursue these answers. It is an astonishing thing that we are — you and I are one of the ways the universe knows itself.

The information you get from social media is not a substitute for academic discipline at all.

I stand by my assertions that although you can know what happens to any individual species that you modify, you cannot be certain what will happen to the ecosystem. Also, we have a strange situation where we have malnourished fat people. It's not that we need more food. It's that we need to manage our food system better.

Climate change is a real deal. So, hey deniers - cut it out, and let's get to work.

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.