 Most satellites are named after people and divinities in Greek and Roman mythology; this is rarely true of asteroids currently, with the exception of centaurs and Jupiter trojans, but formerly many asteroids had mythological names, which consequently came into conflict with the names of natural satellites.Some of these bodies have exactly the same name, referring to the same mythological character.The earliest such conflicts possibly arose through not considering certain mythological names as "official"; for instance, the names Io, Europa, Ganymede and Callisto for the Galilean satellites of Jupiter were not used in astronomical literature of a certain era, their place being taken by "Jupiter I, Jupiter II, Jupiter III, Jupiter IV" (cf.