Science Questions

What causes the Earth to have a magnetic field?

Sun, 18th Mar 2007

Part of the show Cambridge Science Festival Q&A

Question

Tristan, Australia asked:

What causes the Earth to have a magnetic field?

Answer

 

Dave They're not sure but they think its to do with the centre of the Earth being a liquid metal ball and you get convection currents in that. There's a strange thing where it excites itself and turns itself into a dynamo, you get electric currents which make an electro magnet and that's what they reckon is making the magnetic field.

Chris The field does flip from time to time doesn't it? I think the average is about every 100, 000 years, but in fact its less than that.

Dave Yes, they reckon we're due for one fairly soon as the Earth's magnetic field is getting weaker very fast.

Chris So does the North pole become the South Pole?

Dave Yes.

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