Undetected City-Killer Asteroids Threaten Cities, NASA Warns

NASA experts warn that thousands of mid-sized near-Earth asteroids (roughly 140 meters and larger) could strike regional cities, but most remain undetected; scientists estimate up to 25,000 such objects exist near Earth, with only about 40% identified so far, highlighting gaps in detection and defense, despite progress like the Near-Earth Object Surveyor telescope and lessons from the DART mission, with experts urging more funding and planning to prevent regional catastrophes.