abstract:In the theory of Lorentzian manifolds, spherically symmetric spacetimes admit a family of nested round spheres. There are several different types of coordinate chart which are adapted to this family of nested spheres; the best known is the Schwarzschild chart, but the isotropic chart is also often useful.
Italsocontainstheperturbationsofthe Moon onto theearth-moon barycenter and the relativistic perturbations expressed in isotropic and standardcoordinates.