You're safe -- the asteroid known as 2000 EM26 did not hit Earth Monday night. Scientists predicted it wouldn't. But by interstellar standards, this block of rock the length of three football fields was on our front porch.
Image: slooh.com Meteor over Chelyabinsk, a city of about 1 million in Russia, on February 15, 2013.
As our cover story "Space Invader" explains this week, these so-called near-Earth objects (NEOs) are much more common, more potentially hazardous, and just plain more interesting than people realized a few decades ago. That's why the University of Arizona is leading a program to launch a spacecraft in 2016 that will land on an asteroid -- for five seconds -- and retrieve a sample that later will be analyzed on Earth.More »