But to carve the Grand Canyon, Earth required millions of years. To excavate Meteor Crater, the universe, using a sixty-thousand-ton asteroid traveling upward of twenty miles per second, required a fraction of a second. No offense to Grand Canyon lovers, but for my money, Meteor Crater is the most amazing natural landmark in the world.

My goal is not to shove information into your head. It's to find ways to reignite the curiosity that we all had as children for the natural world. You don't have to tell a child to explore the backyard.

I can't think that leaving Earth once is enough.

If I'm looking fit and I'm not, then I'm cheating.

You know, dark matter matters.

Dreams about the future are always filled with gadgets.

The number of people in the world engaged in this search for catastrophic impactors totals one or two dozen. How long into the future are you willing to protect Homo sapiens on Earth? Before you answer that question, take a detour to Arizona's Meteor Crater during your next vacation.