To view space as, "Well, let's go to Mars now," or "Let's do this now," maybe we should rethink of space as our backyard and have a suite of launch vehicles that can enable any ambition a person has regarding space. It's the same way you can go to buy a car: I want to go offroading, I'll buy this model. I'm a city driver, that's this model. I want to use less fuel, well, that's this model. They're not selling you one car, you have options. So when I think of space, I think of having options.

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

My only hope is that every other alien civilization isn't doing exactly what we are doing because then everybody would be listening, nobody would be receiving, and we would collectively conclude that there is no other intelligent life in the universe.

I've known from long ago that the universe was calling me. If you were one of those annoying adults that said, 'Oh, what are you gonna be when you grow up?' I would say, 'Astrophysicist .' And then they'd walk away real quickly.

Private enterprise can never lead a space frontier. It's not possible because a space frontier is expensive, it has unknown risks and it has unquantified risks.

I try to write in a way where you care deeply what the next paragraph will be. I hear the rhythm of prose and that, to me, distinguishes great writing from ordinary writing. By the way, I don't even claim that I'm good. I claim that I value it.

Dark matter and dark energy are two things we measure in the universe that are making things happen, and we have no idea what the cause is.