Heavily-cratered Callisto is only a little smaller than Ganymede and, like Europa, might be hiding a subterranean ocean.布满陨石坑的克利斯托星仅仅稍小于格尼梅德星，它可能与欧罗巴星相似,蕴藏着地下海洋。
Icy Callisto appears to be the most heavily cratered object in the solar system.冰冻的木卫四看上去像是太阳系中表面坑洞最多的一个星体。