The 640 - 1400 metre wide asteroid 2003 UC20 will make a close pass (52.4 lunar distances, 0.1348 AU) travelling at 12.26 km/second, to the Earth-Moon system on the 31st October 2014 @ 07:44 UT ±00:01.
The 610 - 1400 metre wide asteroid 2003 UC20 will make a close pass (25.7 lunar distances, 0.0659 AU), travelling at 8.01 km/second, to the Earth-Moon system on the 29th December, 2012 @ 19:26 UT ±00:01.