The space rock, called asteroid 2011 MD, is the second space rock to zip extremely close to the Earth this year.

　　The asteroid, with latest size estimates ranging from 16 to 66 feet (5 to 20 meters) wide, was discovered just last week on June 22, but there was never any risk of it impacting the Earth, NASA scientists said.

　　That means asteroid 2011 MD would likely be too small to survive the fiery plunge through the Earth's atmosphere, let alone reach the surface, NASA scientists said. Asteroids this size can be expected to buzz Earth with close shaves about once every six years, they added.

　　The space rock flew well below geosynchronous satellites, which orbit 22,236 miles (35,786 km) above the Earth, but well above the 220-mile (354-km) altitude of the International Space Station.

　　There was little chance that the asteroid would hit a satellite because of the vastness of space and relatively small number of satellites, experts said.(本文由在线英语听力室整理编辑)