Building a model of the lunar core using laser ranging observations of the Moon

We discuss the problem of developing a theory of the Moon's physical libration for the model that takes into account the presence of a liquid core. Facts are presented that testify to the existence of a small lunar liquid core. The possibilities of determining from observations the effects of the existence of the lunar core and determining its characteristics, primarily the flattening of the core, are considered. A description of the solution to the problem of including a two-layer model for the task of numerical solution of the equations of physical libration of the Moon is given.