When an asteroid heads for Earth, it’s time to reconsider those doomsday plans

Chicken Little is right. The sky is falling.

The million-plus people living in Chelyabinsk, Russia, got that message on February 15, when a space rock some 17 meters across detonated over their homes. People rushed to the windows in wonderment as a blaze of light arced through the sky; seconds later many of them got a face full of glass shards.