A → periodic comet that is the progenitor of the → Leonids meteor shower. It has a period of 33 years, a → perihelion of 0.982 → astronomical units, an → eccentricity of 0.904, and an → inclination of 162.7°. It was first discovered in 1865 though its past appearances have been traced back to 1366. Tempel-Tuttle is estimated to have a nucleus of radius 1.8 km and a mass of 1.2 × 1013 kg. Also designated 55P/Tempel-Tuttle.
Named after the German astronomer Ernst Wilhelm Tempel (1821-1889) and the American astronomer Horace Parnell Tuttle (1837-1923), who independently discovered the comet on December 19, 1865 and January 6, 1866 respectively.