On the geometry and behavior of n -body motions

The kinematic separation of size, shape, and orientation of n -body systems is investigated together with specific issues concerning the dynamics of classical n -body motions. A central topic is the asymptotic behavior of general collisions, extending the early work of Siegel, Wintner, and more recently Saari. In particular, asymptotic formulas for the derivatives of any order of the basic kinematic quantities are included. The kinematic Riemannian metric on the congruence and shape moduli spaces are introduced via O ( 3 ) -equivariant geometry. For n = 3 , a classical geometrization procedure is explicitly carried out for planary 3-body motions, reducing them to solutions of a rather simple system of geodesic equations in the 3-dimensional congruence space. The paper is largely expository and various known results on classical n -body motions are surveyed in our more geometrical setting.