1. 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 Earth from being here today? What implications do your answers have for the possibility of Earth-like planets around other stars? Take into account the climate histories of Venus and Mars, as they make it clear that it is not easy to get a pleasant climate like that of Earth. How does this affect your opinion about whether Earth-like planets might exist around other stars?