On November 13, 2020, a small asteroid designated 2020 VT4 passed just 370 kilometers (230 miles) above the South Pacific Ocean. For comparison, the International Space Station orbits at an average altitude of 408 kilometers. This flyby set the record for the closest documented non-impacting asteroid close approach in modern astronomical history.
The object was estimated at 5 to 10 meters in diameter, roughly the size of a standard family passenger bus. Because it approached Earth from the direction of the Sun, ground-based survey telescopes could not spot it beforehand. The Asteroid Terrestrial-impact Last Alert System (ATLAS) at Mauna Loa Observatory detected it fifteen hours after closest approach as it receded into deep space.
Had 2020 VT4 hit Earth directly, its small size means it would have produced a dramatic high-altitude fireball bolide rather than ground devastation. Atmospheric friction would have detonated the rock roughly 30 kilometers above the ocean, releasing energy comparable to a small tactical detonation, with negligible shockwave reaching the surface.
Earth gravity dramatically altered 2020 VT4 orbit during its brush with the atmosphere. Its orbital period around the Sun dropped from 749 days to 316 days, transforming it from an Apollo-class asteroid crossing Earth orbit to an Aten-class asteroid spending most of its time inside Earth path.