The 920 - 2100 metre wide asteroid 1997 WS22 will make a close pass (47.1 lunar distances, 0.1209 AU), travelling at 12.54 km/second, to the Earth-Moon system on the 21st May 2014 @ 19:00 UT ±00:01.
See more
The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).