They found that, assuming the second moon was indeed smaller than the main one, and was made of similar stuff (which, given that it is assumed to have formed from the same ring of debris, seems reasonable).
他们发现,假设第二个月
确实比最大的月
(译者注:指的是 原月)要小,并且由相似的物质组成(考虑到这个月
是从岩屑的同样光环形成的,说它们为相似的物质好像也有道理)。