Whether we study igneous rocks, oceans, or magnetospheres, all geoscientists are inherently planetary scientists. Earth and planetary sciences are inextricably linked, as the Earth is but one of a set of planets orbiting a common star. Our solar system evolved from a single cloud of gas and dust that spawned the Sun, planets, comets, and asteroids. The scientific bond among these objects is obvious to those of us who study the other planets, in large part because we typically began studying terrestrial geology and only later delved into planetary science. In contrast, most terrestrial geoscientists have had little formal training in planetary science. Too often, they have only a vague appreciation of why they should even bother to study our nearest neighbors.