* Astronomy

The 490 - 1100 metre wide asteroid 2002 AU4 will make a close pass (39.8 lunar distances, 0.1023 AU), travelling at 11.92 km/second, to the Earth-Moon system on the 21st December, 2012 @ 04:27 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).