The 20 - 45 metre wide asteroid 2011 YQ1 made a close pass (1.0 lunar distances, 0.0026 AU), travelling at 11.81 km/second, to the Earth-Moon system on the 14th December, 2011 @ 14:23 UT ±00:08.
Orbital elements:
2011 YQ1 Earth MOID = 0.0025 AU
Epoch 2012 Mar. 14.0 TT = JDT 2456000.5 MPC
M 45.67469 (2000.0) P Q
n 0.36620515 Peri. 127.65977 +0.82442311 -0.56518408
a 1.9348757 Node 266.77430 +0.50938770 +0.76398038
e 0.5497235 Incl. 1.71562 +0.24667937 +0.31128915
P 2.69 H 25.6 G 0.15 U 6