Near-Earth object the largest explosion in recorded history, equivalent to 20,000 megatons of TNT. It attracted widespread attention because it was discovered only after the closest approach. In March 1998, early orbit calculations for recently discovered asteroid showed a potential 2028 close approach from the Earth, well within the orbit of the Moon, but with a large error margin allowing for a direct hit. Further data allowed a revision of the 2028 approach distance to , with no chance of collision. By that time, inaccurate reports of a potential impact had caused a media storm. From the late 1990s, a typical frame
Near-Earth object return of Halley's Comet was the first comet appearance predicted in advance. The first near-Earth asteroid to be discovered was 433 Eros in 1898. The asteroid was subject to several observation campaigns, because measurements of its orbit enabled a precise determination of the distance of the Earth from the Sun. In has been said that Lexell's comet of 1770 was the first discovered Near-Earth object. In 1937, asteroid 69230 Hermes was discovered when it passed the Earth at twice the distance of the Moon. Hermes was considered a threat because it was lost after its discovery; thus its orbit and