Tuesday, April 24, 2018

electromagnetism - Is reversal of magnetic polarity in a planet an instantaneous occurence?


Just what the title states -


Does reversal of magnetic poles in a planet refer to the point in time when reversal is complete?


OR


Does it refer to the entire drawn out process (assuming the poles flip gradually from 0 through 180 degrees?



Answer




As far as I know the term "reversal of magnetic poles" doesn't have a strict definition, so I suppose different commentators might use it in different ways. However I suspect most of us would use it to describe the whole process.


You describe the process as "drawn out" but no-one knows how long it takes because the dynamics of the Earth's core are poorly understood. On a geological timescale the process looks instantaneous, but then geological timescales are pretty long. Models suggest it could be pretty quick, though how realistic the liquid sodium models are is open to debate.


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