Analysis of analytical and numerical dynamic lunar ephemerides

Abstract This work considers the analysis of libration dynamics of the planets’ moons. To study such processes, it is necessary to use methods for investigating complex systems, as an influence from neighboring celestial bodies on spin-orbital motion of a moon should be taken into account. This fully applies to the Moon’s rotation about its axis. The construction of modern theories of the physical libration of the Moon (PhLM) is based on gravimetric, seismic, satellite observations, and lunar laser ranging, which in its turn has allowed to increase the accuracy by several orders of magnitude compared to the PhLM theories of the end of the 20th century. To satisfy the modern requirements for accuracy of the physical libration theory, it is necessary to apply a precise ephemeris of the Moon’s motion. In this paper, the DE421 modern numerical ephemeris is analyzed. The features of its construction and practical application are studied. The accurate values of ephemeris parameters are produced and an algorithm for determining the Moon’s center of mass coordinates and establishing the angles of physical libration on the basis of DE421 is developed. As a result, a comparative analysis of the physical libration angles with the values produced by the analytic theory of physical libration is conducted. The calculations are made over a time period of 800 years. The comparative analysis shows that significant differences in the ephemerides of 15 and 80 arc seconds in longitude and latitude respectively are caused by the planets’ gravity field, and those impacts should be considered when working with the analytic ephemeris.