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The Earth isn't completely spherical - land at the North Pole is a number of kilometres nearer to the core of the planet than land at the Equator.

事实上，气球并非是一个完美的球体，北极地区要比赤道地区更加接近地心，两地之间的这一差距大概是在数公里。

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Changes in the thickness, viscosity and conductivity of the outer core in the past could have led to convection patterns that caused the magnetic pole to tilt.

过去任何来自于核外层的厚度、粘性和导电性变化都会导致对流形式变化从而引起磁极倾斜。

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