... informed ignorance provides the natural state of mind for research scientists at the ever-shifting frontiers of knowledge. People who believe themselves ignorant of nothing have neither looked for, nor stumbled upon, the boundary between what is known and unknown in the cosmos.

In the end, it's the people who are curious who change the world.

UV is bad for molecules because its high energy breaks the bonds between a molecule's constituent atoms. That's why UV is bad for you, too: it's always best to avoid things that decompose the molecules of your flesh.

The Venus transit is not a spectacle the way a total solar eclipse is a spectacle.

Three and a half million years ago our ancestors - yours and mine - left these traces [indicates footprints]. We stood up and parted ways from them. Once we were standing on two feet, our eyes were no longer fixated on the ground. Now, we were free to look up and wonder.

Let's create a World's Fair that captures everybody's visions of tomorrow together and let's celebrate that vision. Let's have articles on it with illustrators imagining how we'd be living differently.

'As a fraction of your tax dollar today, what is the total cost of all spaceborne telescopes, planetary probes, the rovers on Mars, the International Space Station, the space shuttle, telescopes yet to orbit, and missions yet to fly?' Answer: one-half of one percent of each tax dollar. Half a penny. I'd prefer it were more: perhaps two cents on the dollar. Even during the storied Apollo era, peak NASA spending amounted to little more than four cents on the tax dollar.