The probes have also made the scientists think that under its surface, Europa has a rocky core giving off volcanic heat.

这些探测器还让科学家们认为，在木卫二的表面之下，有一个释放出火山的热量的岩石内核。

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As for that ancient moon's rocky core?

至于那颗古老卫星的岩石内核呢？

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The nucleus might have a small rocky core.

彗核内可能有一个小的石质核心。

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Do planets gradually grow around a rocky core, or can gas giants form spontaneously from lumps in the disc?

ECONOMIST: Astronomers may have stumbled on the birth of a solar system

Despite the fact that it likely contains water and a rocky core, that water is almost certainly in the form of steam or a supercritical fluid.

FORBES: NASA Detects The Light Of A 'Super-Earth'

Dr Marcy suspects that his new discovery, which has about 45 times the mass of the Earth, is composed of a rocky core surrounded by a thick envelope of hydrogen and helium gas.

ECONOMIST: Extrasolar planets