The 11 - 240 metre wide asteroid 2013 SB21 will make a close pass (13.2 lunar distances, 0.0340 AU), travelling at 2.79 km/second, to the Earth-Moon system on the 15th October, 2013 @ 09:25 UT ±00:05.
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The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).