Phew! Giant asteroid passed just 120,000 miles from Earth last night - and nobody saw it coming

An asteroid as big as a 10-story building has passed by Earth at a distance half that of the Moon, researchers have revealed. The asteroid, dubbed 2017 AG13, was only spotted only Saturday by the University of Arizona's Catalina Sky Survey. It is between 50 and 111 feet (15 to 34 meters) long, and when it passed by Earth, 2017 AG3 was moving at 9.9 miles per second (16 kilometers per second). Here, it is so close to Earth its text is almost unreadable. According to an asteroid-impact simulator called'Impact Earth!' by Purdue University, if a porous rock asteroid of 111 feet (34 meters) long hit Earth at a 45-degree angle, the simulator found, it would have exploded as an air burst.