2020 LD is an Apollonear-Earth asteroid roughly 140 meters (460 feet) in diameter. It was discovered on 7 June 2020 when the asteroid was about 0.03 AU (4.5 million km; 12 LD) from Earth and had a solar elongation of 154 degrees. The glare of the Sun had masked the approach of the asteroid since November 2019.[3][a] The asteroid passed closest approach to Earth on 5 June 2020 at a distance of 0.002 AU (300 thousand km; 0.78 LD).[2] The close approach distance is now known with an accuracy of roughly ± 1000 km. This is the largest asteroid to pass closer than the Moon this year and possibly the largest since (308635) 2005 YU55 in November 2011.[b][c] The asteroid makes close approaches to Mercury, Venus, Earth, and Mars.[2] It will be brighter than apparent magnitude 24 until 18 July 2020.
With a short 6 day observation arc it was possible that the asteroid had passed 0.00008 AU (12 thousand km; 0.031 LD) from Earth in June 1918 or would pass 0.0001 AU (15 thousand km) from Venus in April 2024.[4]
With a 11-day observation arc, the Sentry Risk Table lists a 1 in 9 million chance of impact on 7 June 2109.[5]
(501647) 2014 SD224 is another similarly sized asteroid whose close approach will not be masked by the Sun this year.
Recent 100m asteroids passing inside lunar distance
Very few asteroids have known sizes or shapes. The albedo (how reflective the surface is) of these asteroids is often unknown and therefore only generic assumptions can be made about their sizes. A smaller more reflective asteroid can have the same absolute magnitude (H) of a larger less reflective asteroid.
Asteroids in the size range of "2020 LD" (H<24)[b] that passed inside 1 lunar distance from Dec 2011 – June 2020
^The asteroid was within 60 degrees of the Sun from 8 November 2019 until 5 June 2020 07:27 UT.
^ abGiven a generic size estimate of 84–190 meters for 2018 AH, we can not be certain that 2020 LD at a generic estimate of 89–200 meters is larger. Knowing a more precise size requires knowing the albedo (how reflective the surface is.) The albedo combined with the absolute magnitude (H) can help determine the size of an asteroid.