You see the Earth as a bright blue and white Christmas tree ornament in the black sky. It's so small and so fragile - you realize that on that small spot is everything that means everything to you; all of history and art and death and birth and love.

It would take an extremely large spacecraft to deflect a large asteroid that would be headed directly for the Earth.

For the first time in history, we have the chance to change the path of a celestial body. Let's realize what we're talking about here. We would be slightly changing the mechanics of our solar system to enhance our survival. That is gigantic!

Asteroids have hit the Earth millions of times. We can see them as shooting stars every night. When they get bigger, things get complicated. It is only a matter of time until a big one hits us. And since we can do something about it, we should.

We could not wipe ourselves out with a nuclear war. I do not want so sound too positive. It would be a catastrophe, but it would not be a final one. We are not powerful enough for that. An asteroid could be that powerful. That is why we need to do our homework.

By preventing dangerous asteroid strikes, we can save millions of people, or even our entire species. And, as human beings, we can take responsibility for preserving this amazing evolutionary experiment of which we and all life on Earth are a part.

There's no accepted global policy on what to do about asteroid impacts.