Thefirstepisodetracesthedevelopmentofthefourrockyplanetsinoursolarsystem:Mercury,Venus,EarthandMars.Theywerebornatthesametimefromthesamematerial,yethavegoneentirelydifferentpaths.Whatforcesareatworkbehindit?WhyhasEarththrivedwhilsttheothershavefadedaway?Advancedspacemissionsrevealthemomentswhenthefateoftheseworldsturned.
