Swift tuttle comet would pass perilously close to Earth or the Moon on

Comet Swift–Tuttle is a periodic comet with a current orbital period of 133 years. It was independently discovered by Lewis Swift on July 16, 1862 and by Horace Parnell Tuttle on July 19, 1862. It has a well determined orbit and has a comet nucleus 26 km in diameter.

Chinese records indicate that, in 188, the comet reached apparent magnitude 0.1. Observation was also recorded in 69 BC, and it was probably visible to the naked eye in 322 BC. In the discovery year of 1862, the comet was as bright as Polaris. The comet made a return appearance in 1992, when it was rediscovered by Japanese astronomer Tsuruhiko Kiuchi and became visible with binoculars. In 2126 it will be a bright naked-eye comet reaching about apparent magnitude 0.7.

Comet Swift–Tuttle is the largest Solar System object that makes repeated close approaches to Earth. With a relative velocity of 60 km/s. The comet has been described as "the single most dangerous object known to humanity".