Considering the overall process of solar system formation, do you think it was likely for a planet like Earth to have formed? Could random events in the early history of the solar system have prevented our being here today? What implications do your answers have for the possibility of Earth-like planets around other stars? Defend your opinions. (Bennet et al, 2012, p. 189)
Bennett, J., Donahue, M., Schneider, N., and Voit, G.M., (2012). The essential cosmic perspective, 6th ed., Addison Wesley.