Tidal evolution of the Pluto–Charon binary for A = 1, initial θ₀ ≈ 0° and orbit #1 (Table 1). We plot the evolution of Pluto’s rotation period (a), semi-major axis (b), inclination between orbital planes (c), and eccentricity (d) as a functionof time, and the evolution in the (e, ω) diagram (e). The different colors highlight the three evolution stages, initial semi-major axis and eccentricity increase (green), Lidov-Kozaicycles (red), final semi-major axis and eccentricity damping (blue).