O Io o le masina lona lima mai Iupita. E tusa ma le 42.5 itula e faʻamaeʻa ai se taamilosaga faataamilo ia Iupita (vave tele mo lona gaioiga e matauina i le tasi po o le mataʻituina). Io o loʻo i le 2:1-motion orbital resonance ma Europa ma le 4:1-motion orbital resonance ma Ganymede, faʻamaeʻaina lua taamilosaga o Iupita mo taamilosaga taʻitasi uma na faʻamaeʻaina e Europa, ma fa taamilosaga mo taamilosaga taʻitasi na faʻamaeʻaina e Ganymede. O lenei resonance fesoasoani ia Io's eccentric orbital moon (0.0041), lea e maua ai le gaioiga faʻaletonu i le taamilosaga autu mo le taʻitaʻia o le taamilosaga taʻitaʻi e ala i le taamilosaga taʻitaʻi.
42.5 itula