Illustration: Alan Stonebraker, adapted from a NASA image

Figure 1: A small satellite moving under the influence of a sun-earth system will rotate in fixed relation to the sun-earth system if it is located near one of five Lagrange ($L$) points. The figure shows the equipotential lines of the effective potential in the rotating frame. In the atomic analog the effect of the earth is replaced by a circularly polarized microwave field so that the electronic wave packet moves without spreading around the nucleus following the direction of the microwave field. (Figure not to scale).