- Broida 1640
Scott Tremaine, Institute for Advanced Study, Princeton University
Laplace argued, correctly, that the small inclinations of planetary orbits implied that the solar system formed from a flat disk. The observational and theoretical evidence on whether extrasolar planetary systems are flat, however, is still ambiguous. I will discuss constraints on flatness from the Kepler spacecraft and other sources; measurements of the Rossiter-McLaughlin effect in transiting planets, which show that many planetary systems have misaligned stellar spin and planetary orbital angular momenta; Lidov-Kozai oscillations; and competing migration mechanisms for the formation of giant planets at small orbital radii.