Jean-Louis Pons

Jean-Louis Pons (24 December 176114 October 1831) was a French astronomer. Despite humble beginnings and being self-taught, he went on to become the greatest visual comet discoverer of all time: between 1801 and 1827 Pons discovered thirty-seven comets, more than any other person in history.

Pons worked at three observatories in his career, Marseille Observatory, where he was also trained, a short-lived observatory at Royal Park La Marlia in Tuscany, and finally at an observatory in Florence.

Pons's work supported some famous comet recoveries of the 19th century, including Encke's Comet and Crommelin's Comet. However, most of the comets he discovered had parabolic orbits and would not return for a time as long as several millennia.

Early life

Pons was born in Peyre, Hautes-Alpes, to a poor family; he received little formal education. In 1789, he began working for the Marseille Observatory as a caretaker, and gradually gained some experience in assisting the astronomers with observations. He learned to make observations himself, showing a remarkable ability to remember star fields and note changes in them.

In his early astronomical career, the unassuming and trusting Pons was often the target of jokes perpetrated by more experienced astronomers. Franz Xaver von Zach once advised him to look for comets when sunspots were visible, though in doing so Zach may have inadvertently given Pons very good advice.Calder, N. ''Comets: Speculation and Discovery'', Courier, 1994, p. 80

Career as an astronomer

Pons made his first comet discovery, jointly attributed to Charles Messier, on 11 July 1801. He appears to have used telescopes and lenses of his own design; his ''"Grand Chercheur"'' ("Great Seeker") seems to have been an instrument with large aperture and short focal length, similar to a "comet seeker". However, he was not an especially diligent recorder of his observations, and his notes were often extremely vague. However, he found approximately 75% of all comets in this period.

In 1813 he gained the position of Assistant Astronomer at Marseille Observatory.

In 1819, Pons became the director of the new observatory at Marlia near Lucca, which he left in 1825 to teach astronomy at La Specola, in Florence. Around that time he accepted the opportunity to become Director of the Florence Observatory at the request of the Grand Duke of Tuscany.

He discovered five periodic comets, three of which, 7P/Pons–Winnecke, 12P/Pons–Brooks and 273P/Pons–Gambart, bear his name. One observed on 26 November 1818 was named Comet Encke (now 2P/Enke) after Johann Franz Encke, who calculated its orbit and its remarkably short (3.3 y) period (Encke, however, continued to refer to the comet as "Pons's Comet" or "Comet of Pons"). Pons also co-discovered the comet formerly known as "Pons–Coggia–Winnecke–Forbes" and today known as 27P/Crommelin