Where there's water on Earth, you find life as we know it. So if you find water somewhere else, it becomes a remarkable draw to look closer to see if life of any kind is there, even if it's bacterial, which would be extraordinary for the field of biology.

Practically every food you buy in a store for consumption by humans is genetically modified food. There are no wild, seedless watermelons. There’s no wild cows.

If you want to assert a truth, first make sure it's not just an opinion that you desperately want to be true.

All tweets are tasty. Any tweet anybody writes is tasty. So, I try to have each tweet not simply be informative, but have some outlook, some perspective that you might not otherwise had.

The universe has really never made things in ones. The Earth is special and everything else is different? No, we’ve got seven other planets. The sun? No, the sun is one of those dots in the night sky. The Milky Way? No, it’s one of a hundred billion galaxies. And the universe - maybe it’s countless other universes.

NASA has spin-offs, and it's a huge and very impressive list, including accurate and affordable LASIK eye surgery.

The day we stop exploring is the day we commit ourselves to live in a stagnant world, devoid of curiosity, empty of dreams.