Comet Swift–Tuttle (109P/Swift–Tuttle) is a periodic comet with an orbital period of 133 years. It fits the classical definition of a Halley-type comet with a period between 20 and 200 years. It was independently discovered by Lewis Swift and Horace Parnell Tuttle in July 1862. It has a well-known orbit and has a comet nucleus 26 km in diameter.