Asteroid: Doomsday or Payday?

The asteroid that exploded over Siberia—injuring more than 1,000 and damaging buildings in six cities—was a shocking reminder that Earth is a target in a cosmic shooting range. From the width of a football field to the size of a small city, these space rocks have the potential to be killers. In a collision with Earth, they could set off deadly blast waves, raging fires and colossal tidal waves.