Introduction

Let the first planet have position vector , mass , and the standard osculating elements , , , , , and . (See Section 4.12.) It is convenient to define the alternative elements , , , , and , where is the mean orbital angular velocity, , and is the solar mass. Thus, the osculating elements of the first planet become , , , , , and . Let , , , , , and be the corresponding osculating elements of the second planet. Furthermore, let the second planet have position vector , mass , and mean orbital angular velocity , where .