The 12 - 27 metre wide asteroid 2014 KM22 will make a close pass (18.7 lunar distances, 0.0480 AU), travelling at 4.35 km/second, to the Earth-Moon system on the 28th May 2014 @ 08:37 UT ±00:20.
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The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).