* Astronomy

The 48 - 110 metre wide asteroid 2013 RL21 will make a close pass (59.3 lunar distances, 0.1523 AU), travelling at 4.29 km/second, to the Earth-Moon system on the 29th September, 2013 @ 22:49 UT ±00:10. 

See more

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