* Astronomy

Orbital elements:
2012 YO1                                            PHA, Earth MOID = 0.0422 AU
Epoch 2012 Sept. 30.0 TT = JDT 2456200.5                MPC
M 341.60591              (2000.0)            P               Q
n   0.40561866     Peri.  312.48467     +0.74981996     -0.59090350
a   1.8074131      Node    85.94830     +0.66002013     +0.63653256
e   0.4856637      Incl.   17.36204     +0.04629754     +0.49564034
P   2.43           H   21.3           G   0.15           U   9

MPEC 2012 - Y12 

The 150 - 340 metre wide asteroid 2012 YO1 made a close pass (39.0 lunar distances, 0.1003 AU), travelling at 15.58 km/second, to the Earth-Moon system on the 18th December, 2012 @ 17:05 UT ±00:17. 

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