* Astronomy

The 16 - 37 metre wide asteroid 2013 XH22 will make a close pass (1.9 lunar distances, 0.0050 AU), travelling at 19.33 km/second, to the Earth-Moon system on the 18th December, 2013 @ 11:58 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).