Panorama historique de l’étude de la réfraction astronomique : une histoire méconnue entre optique, mathématiques et géodésie

Abstract

From Greek antiquity to the era of computer science, astronomical refraction has raised questions about the real angular position of celestial bodies as seen from Earth surface, the structure of its atmosphere, and the celestial navigation. After introducing the embryonic ideas and the first measurements, the article first presents the early founders of a mathematically structured study: Cassini, Newton, Taylor—the last two inventing appropriate mathematical tools. Then the 18th century geodesists (Bouguer, Lacaille, etc.) enrich the corpus of observations to be understood, followed by the “classics”—Simpson, Bradley, Kramp, Laplace. The progress in metrology allows precise studies of the air refractive index and new theoretical efforts with Biot’s omnipresence. This gain in accuracy requires new calculations involving more sophisticated atmospheric models, as Radau and Ivory, among others, will do. Ivory pointing out a divergence in the numerical series being used, Kummer and Hausdorff find a new mathematical way. Numerical work on computers is eventually making useless all this mathematical virtuosity, although present work keeps relying on Biot’s theoretical advances.