She fer jeh eaystyn Jupiter eh Ganymede (Jupiter III). She eshyn yn eayst smoo er mooadys as er glout mastey eaystyn Chorys ny Greiney. Y nuyoo corpane (goaill stiagh y Ghrian hene) smoo ayns Corys ny Greiney, she Ganymede y fer smoo gyn aeraght ondagh. T'eh 5,268 km (3,273 mi) er crantessen as, rere shen, t'eh 26% ny smoo na Curain er thummid, ga nagh vel eh agh 45% cha mooar as Curain.[3] Ta cree meainagh echey as faghteyr moment y neughleashaght sloo mastey dagh corpane creoi 'sy Ghrianchorys. She Ganymede yn un eayst as ream magnaidagh echey. Magh ass Jupiter, she Ganymede y shiaghtoo eayst as y trass mastey ny h-eaystyn Galileagh, y chied phossan jeh corpaneyn va feddynit as ad cruinlaghey planaid elley.[4] Ta Ganymede cruinlaghey Jupiter ayns mysh shiaght laaghyn as ta aavuilley cruinlagh echey er 1:2:4 lesh ny h-eaystyn Europa as Io, er lheh.