2014 LY21

 is a near-Earth asteroid of the Aten group, approximately 4 - 8 m in diameter. On 3 June 2014 around 17:38 UT (± 3 hours), it is crudely estimated to have passed about 0.00013 AU from Earth. The asteroid was discovered on 2 June 2014 by the Mount Lemmon Survey at an apparent magnitude of 21 using a 1.5 m reflecting telescope.

Uncertainty
With an observation arc of about 1 hour, the trajectory is poorly constrained and the asteroid has an uncertainty parameter of 9 making long-term predictions of the asteroids position nearly impossible. The nominal (best fit) orbit shows that passed 0.00013 AU from Earth on 3 June 2014 (~12,700 km from Earth's surface). But the uncertainty region shows that the asteroid could have approached Earth as close as 0.00006 AU or as far as 0.0005 AU. Since Earth has a radius of approximately 6,400 km, the asteroid did not come any closer than about 2,600 km from Earth's surface.

Moon
The nominal orbit shows that passed 0.001 AU from the Moon on 4 June 2014. But the uncertainty region shows that the asteroid could have impacted the Moon or passed as far as 0.007 AU. But it is very unlikely that the asteroid impacted the Moon.