English: Illustration of tidal acceleration by CMG Lee. In (1), a satellite orbits in the same direction as its parent body's rotation. The nearer tidal bulge (red) attracts the satellite more than the farther bulge (blue), imparting a net positive force in the direction of orbit (dotted arrows showing forces resolved into their components) and lifting it into a higher orbit. In (2), when the rotation is reversed, the net force opposes the direction of orbit, lowering it.