The history of exploration across nations and across time is not one where nations said, 'Let's explore because it's fun.' It was, 'Let's explore so that we can claim lands for our country, so that we can open up new trade routes; let's explore so we can become more powerful.'

I suppose I can live with missing decimals, missing floors to tall buildings, and floors that are named instead of numbered. A more serious problem is the limited capacity of the human mind to grasp the relative magnitudes of large numbers. Counting at the rate of one number per second...to count to a trillion takes 32,000 years, which is as much time as has elapsed since people first drew on cave walls.

I want people to see that the cosmic perspective is simultaneously honest about the universe we live in and uplifting, when we realize how far we have come and how wonderful is this world of ours.

When Kennedy said, 'Let's go to the moon,' we didn't yet have a vehicle that wouldn't kill you on launch. He said we'll land a man on the moon in eight years and bring him back. That was an audacious goal to put forth in front of the American people.

We in astrophysics we think of the universe all the time. So to us, Earth is just another planet. From a distance, it's a speck. And I'm convinced that if everyone had a cosmic perspective you wouldn't have legions of armies waging war on other people because someone would say, "Stop, look at the universe."

We went to the moon and discovered Earth.

We are not figuratively, but literally stardust.