* Astronomy

The 46 - 100 metre wide asteroid 2013 SD20 will make a close pass (21.7 lunar distances, 0.0558 AU), travelling at 12.66 km/second, to the Earth-Moon system on the 28th September, 2013 @ 08:12 UT ±00:04. 

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The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).