Evolution of the effective precession constant of Saturn due to the migration of Titan (adapted from Saillenfest et al. 2021). The top and bottom green curves correspond to the two extreme values of the normalised polar moment of inertia λ considered in this article. They appear into α through Eq. (3). Both curves are obtained using the nominal value b = 1∕3 in Eq. (9). Today’s interval corresponds to the one shown in Fig. 1; it is independent of the value of b considered. The blue line shows Neptune’s nodal precession mode, which was higher before the end of the late planetary migration.