Born “on 4th April 1688, at 6:30 am, in a place in Paris with a latitude of 48°50'50'' ” [1], Delisle “le cadet” or "le jeune" is the ninth of the twelve kids of the historian Claude Delisle and of Nicole-Charlotte Millet de la Croyère. [2] At the end of his classical studies at the Collège Mazarin, he got interested in astronomy by watching the solar eclipse of 12th March 1706. He is introduced to astronomy by Jacques Lieutaud, and began attending the Paris Observatory, where he met Jacques Cassini, who became his second master. He allowed him to copy the solar and lunar tables he was working on. Delisle was admitted to the French Academy of Sciences, as a student of Maraldi. He will never stop contributing to the proceedings of this institution. From the dome of the Luxembourg Palace, he started a lifelong observation program by the lunar eclipse of 23rd January 1712.

He was noticed by Peter the Great, who visited France in 1717, and received in 1721 an invitation to go to Saint Petersburg to establish an astronomical institute. The astronomer gladly accepted, but the tsar remained almost completely silent during the next three years, and died in february 1725. The offer having been immediately reiterated by Catherine the Ist, Delisle could set out at last, in the company of his wife, Madeleine Ledanois, of his brother, Louis De l'Isle de la Croyère (also an astronomer), and of a toolmaker called Vignon. He was supposed to stay at least four years, but eventually remained twenty-one years. In addition to his functions as an astronomer and a professor, Delisle was the main author of a general map of the Russian Empire. 

General map of Georgia and Armenia drawn by Delisle in 1738 "after the maps, dissertations, mesures and observations of the local people", and published in 1766 (Gallica)

Back in Paris in 1747, he established an observatory in the tower of the hôtel de Cluny (today the Middle Ages National Museum). He passed away on September 11th, 1768. His most famous students were Jean-Paul Grandjean de Fouchy, Louis Godin, Joseph Jérôme Lefrançois de Lalande and Charles Messier, not to mention all the ones he trained in Saint Petersburg. 3 A lunar mountain, a crater, and an asteroid bear his name. 

1 Histoire abrégée de ma vie, quoted by Jean Marchand, "Le départ en mission de l’astronome J.-N. Delisle pour la Russie", Revue d’histoire diplomatique, n°43 (1929), p. 373 - 396.

2] The alias "Delisle l’aîné" refers to his brother Guillaume, an important geographer.

3 The sovietic historian Nina I. Nevskaja gives the following list of members of the Academy of Sciences of Saint Petersburg, "on whom he exerted an influence" : "M. V. Lomonossov (1711-1765), L. Euler (1707-1783), Daniel Bernoulli (1700-1782), G. W. Richmann (1711-1753), G. W. Krafft (1701-1769), A. D. Krassilnikov (1705-1773), N. I. Popov (1720- 1782), N. G. Kourganov (1726-1796) and G. Heinsius (1709-1769)." Cf. Nina I. Nevskaja. "Joseph-Nicolas Delisle (1688-1768)", Revue d'histoire des sciences, Vol. 26, No. 4 (octobre 1973), Paris : Armand Colin, p. 289-313.