Published online by Cambridge University Press: 05 June 2012
Cosmochemistry places important constraints on models for the origin of the solar nebula and the formation and evolution of planets. We explore nebula constraints by defining the thermal conditions under which meteorite components formed and examine the isotopic evidence for interaction of the nebula with the ISM and a nearby supernova. We consider how planetary bulk compositions are estimated and how they are used to understand the formation of the terrestrial and giant planets from nebular materials. We review the differentiation of planets, focusing especially on the Earth. We also consider how orbital and collisional evolution has redistributed materials formed in different thermal and compositional regimes within the solar system.
Constraints on the nebula
Understanding the formation of the solar system requires that we delve into processes for which there are no counterparts in terrestrial experience. Grand models for the formation and evolution of the solar nebula are mostly exercises in the physics of gravitational collapse and orbital mechanics. However, cosmochemistry imposes critical constraints on nebular conditions, events, and chronology. In this chapter, we consider how astrophysical models for the formation of the Sun and its accretion disk can be reconciled with cosmochemistry. Theories about how the planets were assembled in the nebula are likewise dominated by physical models of accretion, but cosmochemistry provides information about the nature of precursor materials and the timescales for planet assembly and differentiation.