The 510 - 1100 metre wide asteroid 1988 XB will make a close pass (46.0 lunar distances, 0.1183 AU), travelling at 10.19 km/second, to the Earth-Moon system on the 10th July, 2013 @ 13:19 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).