The 3 - 8 metre wide asteroid 2013 XS21 made a close pass (0.2 lunar distances, 0.0005 AU), travelling at 8.27 km/second, to the Earth-Moon system on the 11th December, 2013 @ 23:27 UT ±00:01.
See more
The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).
