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To my knowledge my knowledge magnetism comes either from an electric current flowing through an object or from a permanent magnet which can be created by heating certain ferrous metals to specific temperatures for the material. To get to my question: I have been told that the core is iron and a permanent magnet formed from the process above, I since seen an article reporting that the core of the earth is thought to be 7000° C yet the curie temperature for iron is about 780°C so this doesn't make sense to me. Could someone explain where this magnetic field originates to me?

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marked as duplicate by Kyle Kanos, user36790, John Rennie, ACuriousMind, Michael Seifert Jan 24 '16 at 14:34

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    $\begingroup$ The magnetic field is predict to be generated by currents flowing in the liquid outer core. You are correct that the high temperatures seem to rule out a permanent magnetic core, even though the Curie temperature of the material in the inner core will, most likely, differ somewhat from that of normal pressure iron. My guess would be that it should be quite a bit higher because the enormous pressure increases the density considerably, which increases the magnetic coupling that leads to ferromagnetism in the first place. I could be wrong about that, though. $\endgroup$ – CuriousOne Jan 24 '16 at 9:08
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The fact that the curie temperature is less than the core temperature does not stop the core producing the magnetic field by the Dynamo effect. The important thing is that the iron (or whatever is there) is an electrical conductor. I would imagine if the core was below the curie temperature the magnetic field which was produced would be much larger.

Lots on the Internet about the origin of the Earth's magnetic field and here is a reasonable starting point?

https://en.m.wikipedia.org/wiki/Earth%27s_magnetic_field#Physical_origin

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    $\begingroup$ Thank you but what I get from reading that is its a dynamo effect from a liquid outer core rotating around a solid core inducing an electric current flow in the outer core "the presently accepted dynamo theory as an explanation of the Earth's magnetism, proposed that this magnetic field resulted from electric currents induced in the fluid outer core of the Earth." But without one of the layers being a permanent magnet which would induce current into a moving conductor. How is the current induced in the first instance. Is it from the friction as with glass and silk perhaps? $\endgroup$ – Donnie Hynes Jan 24 '16 at 10:18
  • $\begingroup$ I would imagine that in the beginning there was a "background" magnetic field which increased as the Dynamo got going? $\endgroup$ – Farcher Jan 25 '16 at 6:35

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