How did the moon remain magnetic tens of millions of years after its molten core stopped sloshing?

月球炽热的内核停止了翻滚已几千万年了，它是如何保持磁场的？

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Neither Mars nor Venus has a magnetic field like the Earth's, which is generated by currents in the planet's molten core.

无论是火星还是金星都没有同地球一样的磁场，地球的磁场是由地球熔融核心中的电流产生的。

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Somewhere at the boundary of Gaia, either in the rarefied airs of the stratosphere or deep in the Earth's molten core, the effects of life fade.

盖亚疆域的某处，或是稀薄的大气同温层或是地球深处炽热的核心，在那儿生命的影响力式微。

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That suggests these rocks have been near a molten iron core.

BBC: A fleeting encounter with an 'inbetweener'

The magnetometer will record what, if any, magnetic field the asteroid has, thus revealing whether it was ever part of an object large enough to have possessed the molten iron core needed to generate such a field.

ECONOMIST: An erotic encounter

Japanese researchers say the basalt in NWA 011 suggests the body from which it did originate had a core of molten iron with an outer covering of silicon and aluminium that formed a basaltic crust.

BBC: Mercury meteorite puzzle