Even if we knew precise details of Earth's core, we would not be able to predict a catastrophic flip in the polarity of its magnetic field more than a decade or two ahead.

Our planet's magnetic field has reversed polarity from time to time throughout its history. Some models suggest that a flip would be completed in a year or two, but if, as others predict, it lasted decades or longer we would be left exposed to space radiation. This could short-circuit satellites, pose a risk to aircraft passengers and play havoc with electrical equipment on the ground.

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