Using information obtained from around a dozen earthquakes detected on Mars by the Very Broad Band SEIS seismometer, developed in France, the international team of NASA's InSight mission has unveiled the internal structure of Mars. The three papers published on July 23, 2021 in the journal Science, involving numerous co-authors from French institutions and laboratories, including the CNRS, the Institut de Physique du Globe de Paris, and Université de Paris, and supported in particular by the French space agency CNES and the French National Research Agency ANR, provide, for the first time, an estimate of the size of the planet's core, the thickness of its crust and the structure of its mantle, based on the analysis of seismic waves reflected and modified by interfaces in its interior. It makes this the first ever seismic exploration of the internal structure of a terrestrial planet other than Earth, and an important step towards understanding the formation and thermal evolution of Mars.