The Asteroids Approaching Earth That Keep NASA Scientist Up at Night

NASA’s planetary defense boss just admitted what keeps her tossing and turning: not the giant dino-killers we track, not the pebble-sized ones that burn up daily, but the sneaky “city killers”—those 140-meter-plus rocks we’ve only cataloged 40% of. There could be 25,000 lurking out there, undetected, ready to turn a metropolitan area into a crater party. We’ve got telescopes, sure, but space is big and sneaky asteroids don’t RSVP. Sweet dreams, humanity—hope that next space rock has your city’s name on it. Or not. Fingers crossed!