TDEI stability diagram for celestial bodies of the solar system. Considering a surfacic viscous damping term of the growth rate σ_s =  −α  f(η)  E^1/2 (see Sect. 3.6), the zone above the black line, defined by (33), is the unstable zone, whereas Y, defined by (31), is calculated with α = 1 and α = 10 for each planet (for the actual Earth and Venus, the difference is very small). The yellow zone is the so-called “forbidden zone”, given by Ω_spin/Ω_orb ∈  [ − 1;1/3] .