Nicolas-Louis de La Caille was born in 1713. He joined the Paris Observatory in 1736, and left it in 1742 in order to teach mathematics at the Mazarin College, where an observatory was built for him. There, he began to assemble a stellar catalogue, but concluded that for a full coverage of the whole sky, it would be necessary to travel to the Southern hemisphere.
127 nights to survey the Southern sky
He obtained the necessary finance and authorizations, and sailed for the Cape of Good Hope in 1750. He was very well received by the governor, who had an observatory built for him. During 127 tireless nights of observation, he carried out the first ever systematic survey of the Southern sky. He catalogued 9 766 stars, most of them previously unlisted, as well as numerous nebular structures.
Before La Caille’s work, large sections of the southern sky had never been mapped. He filled these hitherto virgin regions with 14 new constellations, named after scientific or artistic instruments.
14 new constellations
These names are still in use to-day : Sculptor, Fornax, Horologium, Reticulum, Caelum, Pictor, Pyxis, Antlia, Octans, Circinius, Norma, Telescopium, Microscopium and Mensa (the latter referring to Table Mountain, which overlooks Cape Town). Furthermore, La Caille divided into three parts the enormous constellation of Argo, which thus became Puppis, Carina and Vela.
Making simultaneous observations with Lalande in Berlin, La Caille obtained the best values of his time for the parallax (the distance) of the Moon, Mars and the Sun.
When he returned to Paris, La Caille had made by his friend Anne-Louise Le Jeuneux a magnificent planisphere of the southern sky : this planisphere is now at the Observatory. He took up his teaching duties and continued observing, but died prematurely in 1762.
- The exhibition "L’abbé La Caille, découvreur du ciel austral"
- The virtual exhibition online
Dernière modification le 28 août 2014