Projected equilibrium spin axes on the orbital plane for varying core-mantle viscous friction, assuming a spherical core. a) Mantle spin axis coordinates. b) Core spin axis coordinates. The vertical line labelled Cassini plane in panel a) is the intersection of the Cassini plane with the orbital plane. Red dots indicate coordinates from Peale et al. (2014, Table 2). The observations are taken from Margot et al. (2012); Mazarico et al. (2014); Stark et al. (2015a); Verma & Margot (2016); Genova et al. (2019); Konopliv et al. (2020); Bertone et al. (2021).