* Astronomy

The 24 - 54 metre wide asteroid 2013 SD21 will make a close pass (12.9 lunar distances, 0.0332 AU), travelling at 8.83 km/second, to the Earth-Moon system on the 5th October 2013 @ 18:44 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).