The short-period comet with the shortest known period at around 3.3 years. It was discovered independently by Pierre Méchain in 1786, by Caroline Herschel in 1795, and by Jean-Louis Pons in 1805 and again in 1818. In 1821 Johann Encke calculated the orbit of Pons's 1818 comet and predicted its return to perihelion in 1821 to an accuracy of one day