Abstract

Planets embedded in a planetesimal disk will migrate as a result of angular momentum and energy conservation as the planets scatter the planetesimals that they encounter. A surprising variety of interesting and complex dynamics can arise from this apparently simple process. In this chapter, we review the basic characteristics of planetesimal-driven migration. We discuss how the structure of a planetary system controls migration. We describe how this type of migration can cause planetary systems to become dynamically unstable and how a massive planetesimal disk can save planets from being ejected from the planetary system during this instability. We examine how the solar system's small-body reservoirs, particularly the Kuiper belt and Jupiter's Trojan asteroids, constrain what happened here. We also review a new model for the early dynamical evolution of the outer solar system that quantitatively reproduces much of what we see. And finally, we briefly discuss how planetesimal-driven migration could have affected some of the extrasolar systems that have recently been discovered.