Halley’s Comet is a short-period comet visible from Earth every 74-79 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and the only naked-eye comet that might appear twice in a human lifetime. Halley last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061.
The comet’s periodicity was first determined in 1705 by English astronomer Edmond (or Edmund) Halley (8 November [O.S. 29 October] 1656 – 25 January 1742 [O.S. 14 January 1741]), after whom it is now named. He predicted the comet’s return in 1758, which he did not live to see.
Halley’s returns to the inner Solar System have been observed and recorded by recognized astronomers since at least 240 BC. Clear records of the comet’s appearances were made by Chinese, Babylonian, and medieval European chroniclers, but were not recognized as reappearances of the same object at the time.