The 77 - 170 metre wide asteroid 2004 HB39 will make a close pass (62.5 lunar distances, 0.1605 AU), travelling at 8.88 km/second, to the Earth-Moon system on the 20th June, 2012 @ 09:18 UT ±16:08.
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The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).