How dangerous are near-Earth asteroids? 5 key questions answered.
On Feb. 15, asteroid 2012 DA14, discovered a year ago, cleared Earth by a scant 17,200 miles. The same day, a smaller, unrelated asteroid that no one saw coming exploded 12 to 15 miles above Russia’s Chelyabinsk region. Events that day highlight the risk that near-Earth objects (NEOs) can pose – although to some extent, humans can counter them.