Un effet Doppler-Fizeau méconnu : Roemer et la vitesse de la lumière / An unrecognized Doppler-Fizeau effect : Roemer and the speed of light

SUMMARY. — Roemer proved that the speed of light is finite from the advances and retardations observed in the revolutions of a satellite of Jupiter. Since these variations are modifications of the apparent frequency of a periodic phenomenon viewed by a moving observer, Roemer thus came across the Doppler-Fizeau effect, even before it was clearly defined. In this paper, I show how Roemer's analysis can be harmonized with that well-known effect. I try to evaluate Romer as a precursor of Doppler and Fizeau.