ABSTRACT
Perturbation theory is more general and more comprehensive then n-body theory; for perturbation theory the very nature of the perturbations or of their source is not important. There are two trends or two approaches to the computation of the perturbations, i.e. of the corrections to be added to the ideal, unperturbed trajectory – that on a conical section – in order to obtain the real position of a celestial body at a given moment in time. Obviously, in the limit one should have a continuously acting perturbation, and the real trajectory of motion turns, to a conditional ellipse with continuously changing elements. The chapter considers the qualitative aspects of the problem of the influence of the perturbation force on the elements of the orbit. The problem will be the derivation of differential equations determining the dependence between the osculating elements, their derivatives with respect to time, and the components of the perturbing acceleration.
