The 10 - 21 metre wide asteroid 2015 HC1 will make a close pass (21.9 LD, 0.0562 AU) travelling at 2.58 km/second, to the Earth-Moon system on the 29th April 2015 @ 22:16 UT ±00:34.
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The Lunar Distance (LD), the distance between Earth and the Moon, equals 384,401 km, (or 0.00256 AU).