* Astronomy

Orbital elements:
2012 YS1                                                 Earth MOID = 0.0087 AU
Epoch 2012 Sept. 30.0 TT = JDT 2456200.5                MPC
M 308.54458              (2000.0)            P               Q
n   0.39372493     Peri.   77.70025     -0.97084736     -0.20413082
a   1.8436314      Node    90.42231     +0.14005575     -0.90847427
e   0.6120662      Incl.    7.21805     +0.19452450     -0.36469866
P   2.50           H   25.0           G   0.15           U   7

MPEC 2012 - Y17

The 27 - 60 metre wide asteroid 2012 YS1 will make a close pass (8.1 lunar distances, 0.0209 AU), travelling at 17.41 km/second, to the Earth-Moon system on the 24th December, 2012 @ 11:42 UT ±00:01. 

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