Adiabatic invariance of the actions. This figure uses galpy's action–angle routines to demonstrate that the actions are conserved when adiabatically deforming one isochrone potential into another, using TimeInterpPotential defined in Figure 4. In the figures, the blue lines display the orbit in the first potential, the green lines the orbit while the potential is being changed, and the red lines the orbit in the second potential. The top figure shows the orbit projected onto the mid-plane and the bottom figure shows the orbit in the meridional plane.