Abstract

The discovery of extrasolar planets on eccentric orbits has motivated theoretical investigations of numerous mechanisms for exciting the eccentricities of giant planets during the planet formation process and subsequent orbital evolution. The orbital properties of the growing number of extrasolar planetary systems and multiple planet systems are beginning to provide clues that constrain planet formation models. I will discuss the implications of exoplanet observations for eccentricity evolution from planet-disk interactions in young planetary systems to the chaotic evolution of multiple planet systems. I will discuss the potential role of planet scattering in the formation of planets in wide orbits, such as those recently found around A stars. I will also discuss the implications of planet scattering and secular interactions for the orbits of Neptune or super-Earth-mass planets. I will conclude will speculations as to why our own solar system has settled to a state with nearly circular orbits.