Agreements and Disagreements between Theories for a Rigid Earth and Non-Rigid Earth Model

J. Souchay

Observatoire de Paris

The necessity to elaborate a theory of nutation-precession matching the accuracy of very modern techniques as Very Long Baseline Interferometry and Lunar Laser Ranging led recently to various works. We discuss the good agreement between those related to the nutation when considering the Earth as a solid body. In comparison we show the uncertainity concerning the modelisation of the transfer function leading to theoretical determination of the nutation coefficients when including predominant geophysical characteristics (elastic mantle, coupling at core-mantle boudary, free core nutation, free inner core nutation etc...).