Five years ago, the 10,000-ton, 56-foot Chelyabinsk meteor exploded over Russia with the force of 30 atomic bombs. Yesterday, an asteroid three to six times larger than that rock came out of nowhere and passed by the Earth at a distance of 119,500 miles, about half the distance to the moon—and scientists only had a few hours' warning before it closed in. The asteroid, dubbed 2018 GE3, passe