On the Importance of a Few Dwarf Planets

Dwarf planets are few in number and often exhibit peculiarities that make them apparent outliers in their neighborhood in the solar system. Studying them and understanding their unusual properties have led to leaps in understanding of our solar system and its history. Probing the peculiarities of Pluto's orbit have led to the recognition of the orbital migration of the giant planets. Ceres, the dwarf planet in the asteroid belt, offers tantalizing prospects of a rich water-ice crust and mantle, and challenges to the standard model of solar nebula compositional gradients. Efforts to place in context several new discoveries of trans-Neptune dwarf planets, such as Sedna and Haumea, are probing collisional physics in the ice-rock parameter regime as well as the role of dynamical chaos or possibly undetected massive perturbers at the edge of our solar system.