Original Story WASHINGTON (Reuters) – An asteroid the size of a soccer field whizzed by Earth at a distance much nearer than the Moon, the biggest such space rock in decades to get this close, scientists said on Thursday.

Asteroid 2002MN was not detected until Monday, three days after its closest approach on June 14, when it got within 75,000 miles of Earth and was traveling at a speed of some 23,000 miles per hour, astronomers said. 
 The big rock, with a diameter of roughly 50 yards to 120 yards, would not have caused global catastrophe if it had struck Earth. That would take an asteroid of several miles in diameter. However, if it had hit Earth, it had the potential to cause as much local devastation as a 1908 hit in Tunguska, Siberia, which flattened some 800 square miles of forest. 
 “It’s a good thing it missed the Earth, because we never saw it coming,” Steve Maran of the American Astronomical Society said in a telephone interview. “The asteroid wasn’t discovered until three days after it passed its closest approach to our planet. 
 An asteroid the size of 2002MN may hit Earth about once every hundred years or so, and the planet may not have seen the last of this one, Marsden said.