The 15 - 33 metre wide asteroid 2013 XS23 will make a close pass (46.5 lunar distances, 0.1194 AU), travelling at 5.83 km/second, to the Earth-Moon system on the 19th May 2014 @ 14:07 UT ±03:32.
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The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).