Or, if not, the moon may never have had the magma ocean that scientists think covered its surface soon after it formed.

若非如此，月球可能从来都没有出现过岩浆海洋。之前科学家们曾认为，月球形成后不久，其表面处于岩浆的状态。

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Smaller than our moon, Europa is covered in water ice that might conceal an ocean of liquid water.

欧罗·巴比我们的月球小一些，表面覆盖冰层，冰下可能有液态水。

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Perhaps the moon never even had a magma ocean and the rocks were formed another way, they suggested.

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。

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Ninety percent of the ocean floor has not even been charted, and while we have been to the moon, the technology to explore the ocean's floors is still being developed.

CNN: Mars can wait. Oceans can't

We've sent more people to the moon than the deepest parts of the ocean.

CNN: Quest for exploration

Apollo 17, the last manned expedition to the Moon, splashed down in the Pacific Ocean on Dec. 19, 1972.

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