According to Cartwright, " An elastic solid spheroid will yield to an external tide potential " U " 2 of spherical harmonic degree 2 by a surface tide " h " 2 " U " 2 / " g " and the self-attraction of this tide will increase the external potential by " k " 2 " U " 2 . " The magnitudes of the Love numbers depend on the rigidity and mass distribution of the spheroid.