The 130 - 300 metre wide asteroid 2008 OX1 will make a close pass (72.9 lunar distances, 0.1873 AU), travelling at 15.35 km/second, to the Earth-Moon system on the 20th July, 2012 @ 06:08 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).