What defines the anomalistic month?

The anomalistic month is defined as the time it takes for the Moon to travel from one perigee to the next; that is, from its closest point to the Earth back to that same point again. This cycle lasts approximately 27.55 days. The significance of the anomalistic month lies in the fact that it highlights the elliptical nature of the Moon's orbit, where perigee (the point of the Moon's closest approach to Earth) and apogee (the point of the Moon's farthest distance from Earth) vary over a cycle.

Understanding this cycle is crucial in various applications, including predicting tides and understanding the gravitational influence of the Moon on Earth. When comparing this definition to other choices, it is clear that they either refer to different aspects of the Moon's movement or to entirely separate phenomena, such as Earth’s rotation or the Moon's overall orbital period.