Due to its own rotation, it is expected that the visual figure of the Sun is a spheroid; this is not truly the case because the solar rotation is not constant both over all heliographic latitudes and in depth. The photospheric shape is thus sensitive to the interior structure: accurate measurements of both limb shape distortions and solar rotation rates determination provide useful constraints on the internal layers (density, shear zones, …). We show why and how the implication of the successive gravitational moments are important to probe the solar interior, and we compare measurements obtained either from space (SOHO/MDI) or from ground-based experiments (scanning heliometer at the Pic du Midi). The found faint departures to the sphericity, not exceeding 22 mas, could explain fluctuations that are not yet taken into account in the classical modelling of the solar irradiance. A crude model could explain the asphericities which is based on a core rotating at a nearly uniform rate combined with a prolate tachocline and an oblate outer convective zone.