https://it.wikipedia.org/wiki/Abitabilit%C3%A0_planetaria https://s3.amazonaws.com/s3.classmill.com/modules/images/fit/abitabilitaplanetaria-3e4f.jpg http://quantity.altervista.org/quanta-acqua-ce-sulla-terra/ https://www.google.com/search?q=gestione+agronomica+delle+risorse+idriche&rlz=1C1ASUT_enIT566IT576&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjq5fTjycrgAhWux4UKHc19CDgQ_AUIDygC&biw=1242&bih=597#imgrc=AoPCpbdtl5Lh2M: https://notizie.tiscali.it/permalink/Osservata-in-diretta-la-nascita-di-un-pianeta/ https://it.wikipedia.org/wiki/Pianeta#Formazione_dei_pianeti_e_dei_sistemi_planetari https://s3.amazonaws.com/s3.classmill.com/modules/images/fit/abitabilitaplanetaria-f511.jpg