Watching over the night
Those who guard planet Earth by looking for asteroids and comets headed our way form a select few — too few, in fact, to let any of us sleep easily.
NASA scientist David Morrison once said that on a typical night, there are more people behind the counter of your local McDonald's than there are scanning the skies worldwide for killer rocks. That's no longer true, but the list of search teams isn't very lengthy. Here are the main on-going programs.