Some levels of the function R defined in (16) for ε = 10⁻³ and γ = 1 in the plane. The two red points correspond to the Lagrange points L₁ and L₂ and the three orange points to L₃, L₄, and L₅. The orange-filled area corresponds to the region where R(x, y) < R(L₁). The star S is at the origin, the planet P₁ at (1,0), and (x,y) are the coordinates of the second planet. The green region represents the Hill sphere of the first planet.