当星球冷却后，覆盖其表面的岩浆海洋开始定形。
As it cooled, an ocean of magma covering its surface began to crystallize.
夏普认为最好的解释就是：月球的岩浆海洋中几乎不存在氢元素。
The best explanation, Sharp says, is that there was hardly any hydrogen in the moon's magma ocean.
他们提出，也许月球甚至从未存在过岩浆海洋或以另一种方式形成的岩石。
Perhaps the moon never even had a magma ocean and the rocks were formed another way, they suggested.
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