音标: 英 [.plæni'tesiml]
1. Instead of worrying about pebbles or rocks or planetesimals, you just take the gas in the early solar nebula and you collapse it down under its own gravity to form one big object.
不必去想什么卵石 岩石和星子 只要有早期太阳星云中的气体就够了 让气体在自身引力作用下崩塌 从而形成一个大的物体