The age-old question of how our home planet and its satellite originated has in recent times undergone a minor revolution. The emergence of the "giant impact theory" as the most successful model for the origin of the Moon has been difficult to reconcile with some aspects of the Earth, and the development of an integrated model for the origin of the Earth-Moon system has been difficult for this reason. However, recent technical advances in experimental and isotopic work, together with intensified interest in the modeling of planetary dynamics, have produced a wealth of new results requiring a...