The 12 - 27 metre wide asteroid 2015 KT56 made a close pass (10.0 LD, 0.0256 AU) travelling at 9.55 km/second, to the Earth-Moon system on the 18th May 2015 @ 14:11 UT ±00:01.
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The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).