He is famous for his observations of the comet he discovered (on December 13, 1743) and observed 1743 until March 1744, although this had been first discovered (on December 9) by Dirk Klinkenberg (comet 1743 Klinkenberg or Klinkenberg-De Chéseaux, C/1743 X1, 1744). De Chéseaux describes this comet in depth, which became brighter than Jupiter and at one time exhibited no less than six tails. He originally discovered another comet two years later, on August 13, 1746: Comet 1746 De Chéseaux (C/1746 P1, 1747).

In 1745 and 1746, De Chéseaux compiled a list of 21 nebulous objects, of which he had originally discovered 8 objects: IC 4665, NGC 6633, M16, M25, M35 (this one might have seen before by John Bevis in England), M71, M4, and M17. Moreover, he independently re-discovered M6, NGC 6231 and M22 (No. 17). De Chéseaux sent this list to his grandfather, Reaumur, in Paris, and it was read by Reaumur at a meeting of the French Academy of Sciences on August 6, 1746 and mentioned by Jean Maraldi in 1746 (Maraldi 1751), by Le Gentil in 1759 (Le Gentil 1765), but then stayed unpublished and more or less forgotten until Guillaume Bigourdan recovered and published it within a larger paper in 1884 (Bigourdan 1892).

De Chéseaux was among the first to formulate Olbers' paradox.

De Chéseaux did not grow very old; he died on November 30, 1751 at age of only 33.

Links

• De Chéseaux's List of 21 "Nebulae" - online translation of the original list
• Jean Phillippe Loys de Chéseaux images, NGC/IC observers page
• Some Phillippe L. de Chéseaux info, Yann Pothier

• Guillaume Bigourdan, 1892. Observations de Nebuleuses et d'amas stellaires (Observations of Nebulae and Star Clusters). Annales de l'Observatoire de Paris. Observations 1884. Paris, Gauthier-Villars, pp. G.1-G.103 [Bibcode: 1892AnPOb..36G...1B]
• Le Gentil, 1759. Remarques sur les Étoiles Nebuleuses. Mémoires de l'Académie Royale des Sciences. Année M.DCCLIX. [Remarks on the Nebulous Stars. Memoirs of the Royal Academy of Sciences. For the year 1759.] Paris, 1763 [Bibcode: 1763MmARS1759..453L].
• Kenneth Glyn Jones, 1969. The Search for the Nebulae -- V. Journal of the British Astronomical Association, Vol. 79, No. 2 (1969), p. 105-112. Section on De Chéseaux: p. 105-108. Reprinted in: The Search for the Nebulae. Chalfont St. Giles, 1975.
• Kenneth Glyn Jones, 1991. Messier's Nebulae and Star Clusters. 2nd ed, Cambridge University Press, pp. 318-9. [ADS: 1991mnsc.book.....J].
• J.-D. Maraldi, 1746. Observations de la Comète qui a paru au mois d'Aout 1746. Mém. Acad. roy. des Sciences pour 1746, p. 55-62, Paris, 1751 [Bibcode: 1751MmARS1746...55M]. De Chéseaux's work is mentioned at the beginning of this article on p. 55.