People say, oh we just need charismatic leaders to continue on to Mars. Now we've gone to the moon, of course Mars is next. No. Mars was never, of course, next. It is next if you think we went to the moon because we're explorers, but if you know we went to the moon because we were at war then we're never going to Mars. There's no military reason to do it, to justify the expenditure.

Science is not there for you to cherry pick ... You can decide whether or not to believe in it but that doesn’t change the reality of an emergent scientific truth.

If each dead person became a ghost, there'd be more than 100 billion of them haunting us all. Creepy, but cool.

And I don't care what else anyone has ever told you, the Sun is white, not yellow. Human color perception is a complicated business, but if the Sun were yellow, like a yellow lightbulb, then white stuff such as snow would reflect this light and appear yellow-a snow condition confirmed to happen only near fire hydrants.

If factual information upsets you, then you are creating a world that is not embracing objective truths, and that's not how you advance a democracy.

With no gravitational force to work against, your body not only doesn't need the same amount of muscle and bone, it starts breaking them down. As on Earth, so in space: use it or lose it. And exercise may not solve the problem.

Thomas Jefferson basically secularized Jesus.