Jean-Philippe de Cheseaux

Jean-Philippe Loys de Cheseaux (; 4 May 1718 – 30 November 1751) was a Swiss astronomer.

Biography

Loys de Cheseaux was born on 4 May 1718 in Lausanne, Vaud, to Paul-Etienne Loys de Cheseaux, a banneret, and Estienne-Judith de Crousaz. His brother was Charles-Louis Loys de Cheseaux. He acquired a reputation in Europe as an astronomer with the publication of his Traité de la Comète, Loys de Cheseaux discovered the comet C/1746 P1. In 1746, he presented a list of nebulae, eight of which were his own new discoveries, to the French Academy of Sciences. The list was noted privately by Le Gentil in 1759, but only made public in 1892 by Guillaume Bigourdan.

From 1747, Loys de Cheseaux was a corresponding member of the science academies of Göttingen, Saint Petersburg and Stockholm, as well as the French Academy of Sciences and the Royal Society of London. He was offered the post of director of the St. Petersburg observatory, but declined the invitation. In 1751, Loys de Cheseaux travalled to Paris and was presented to the Academy of Sciences. There he died, after a short illness, on 30 November 1751, aged 33.

In addition to astronomy, Loys de Cheseaux researched Biblical chronology, calculating the movements of the Sun and Moon relative to descriptions in the Book of Daniel and the occurrence of solstices and equinoxes in Jerusalem at the time of the Old Testament story. In his Dissertation Chronologique (1748), Loys de Cheseaux tried to establish the date of the eclipse known as "crucifixion darkness" in order to determine the date of the crucifixion of Jesus.