Long ago Mars was an oasis of running water.Today the Martiansurfaceis a sterile,barren desert. Here on Earth, who knows what climactic knobs we unwittingly turn,which might one day render Earth as dry and lifeless as Mars. (From the cover of Old Poison by Joan Francis)

Too many people view on [space exploration] as a luxury rather than as a fundamental driver to stimulate interest in science to everyone in the educational pipeline. It's vital to our prosperity and security.

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.

There is no science in this world like physics. Nothing comes close to the precision with which physics enables you to understand the world around you. It's the laws of physics that allow us to say exactly what time the sun is going to rise. What time the eclipse is going to begin. What time the eclipse is going to end.

The best educators are the ones that inspire their students. That inspiration comes from a passion that teachers have for the subject they're teaching. Most commonly, that person spent their lives studying that subject, and they bring an infectious enthusiasm to the audience.

If aliens did visit us, I'd be embarrassed to tell them we still dig fossil fuels from the ground as a source of energy.

In the animal kingdom, one of the keys to survival is to outwit your enemies. And when you're surrounded by carnivores, one of the best strategies is to fade into the background and disappear.