Elliptical enharmonic orbit contains two centers or foci. The smaller center has more energy than the larger, per unit of area. It attracts the planet with more force, hence into a smaller diameter orbit where velocity of orbit (revolution) increases.
The larger center has less energy than the smaller, per unit area. It attracts the planet with less force, hence into a larger diameter orbit where velocity of orbit (revolution) decreases.
Thus maintaining persistent and consistent conformity with Kepler's Laws of Orbiting Bodies: