2014 LY₂₁ is a near-Earth asteroid of the Aten group, approximately 4–8 meters (13–26 feet) in diameter. On 3 June 2014 around 17:38 UT (± 3 hours), it is crudely estimated to have passed about 0.00013 AU (19,000 km) from Earth.^[2][b] The asteroid was discovered on 2 June 2014 by the Mount Lemmon Survey at an apparent magnitude of 21 using a 1.5-meter (59 in) reflecting telescope.^[1]

With an observation arc of about 1 hour,^[a] 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 2014 LY₂₁ passed 0.00013 AU (19,000 km; 12,000 mi)^[2] from Earth on 3 June 2014 (~12,700 km from Earth's surface).^[5][b] But the uncertainty region shows that the asteroid could have approached Earth as close as 0.00006 AU (9,000 km; 5,600 mi) or as far as 0.0005 AU (75,000 km; 46,000 mi).^[2] 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.

The nominal orbit shows that 2014 LY₂₁ passed 0.001 AU (150,000 km; 93,000 mi) from the Moon on 4 June 2014.^[2] But the uncertainty region shows that the asteroid could have impacted the Moon or passed as far as 0.007 AU (1,000,000 km; 650,000 mi).^[2] But it is very unlikely that the asteroid impacted the Moon.

• 2004 FU162
• 2020 QG

• 2014 LY21 at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• 2014 LY21 at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• 2014 LY21 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters