Near-Earth object atmosphere, passing Earth's surface only away (about one Earth radius or one-sixtieth of the distance to the Moon). Because it was very small (6 meters/20 feet), FU was detected only hours before its closest approach. If it had collided with Earth, it probably would have disintegrated harmlessly in the atmosphere. On February 4, 2011, an asteroid designated , estimated at in diameter, passed within of the Earth, setting a new record for closest approach without impact, which still stands . On November 8, 2011, asteroid , relatively large at about in diameter, passed within (0.85 lunar distances) of Earth. On
Near-Earth object In April 2017, the IAU adopted a revised definition that generally limits meteoroids to a size between 30 µm and 1 m in diameter, but permits the use of the term for any object of any size that caused a meteor, thus leaving the distinction between asteroid and meteoroid blurred. Near-Earth comets (NECs) are objects in a near-Earth orbit with a tail or coma. Comet nuclei are typically less dense than asteroids but they pass Earth at higher relative speeds, thus the impact energy of comet nucleus is slightly larger than that of a similar-sized asteroid. NECs may pose an