The earth's iron core, How did it magnetize?

Something that has puzzled me is how did the earth's iron core become so magnetic? If you look at surface iron and iron ores, only a small percentage is naturally magnetic, even though all the surface iron has been bathing in earth's magnetic field during crystalization. At the same time, if one heats natural magnets, once they melt the crystal/atomic alignment gets random and the natural magnetism declines of goes away completely. That is why super magnets work better in extreme cold instead of high heat.

Once a magnetic iron core in the earth is set up, by whatever means, it might be self perpetuating, inspite of the 8000c core temperature increasing the degree of atomic movement in the cystal magnetic alignment. But what was the original magnetic field that helped induced the current magnetic iron core, so the earth's core didn't end up with only a small percentage magnetism, in proportion to what is on the surface?

I like picking on the earth's iron core and magnetic field because it is one of those dogmas of science, very similar to those in religion, i.e., strongly help while unprovable. One sort of gets the same reaction from science as one gets from religion, if you dare question the unprovable that is accepted as truth.

If you look at the history of this dogma it is at least 200 years old and could have been deduced in Faraday's time. First of all, lodestone has been known to have magnetic properties for thousands of years. By the iron age it was probably known to contain iron. Little pieces of lodestone had been used to help navigate ships and was the basis of the first compasses for centuries before Faraday.

When Faraday experimented with magnetic field and saw how they were aligned around a magnetic, the logical speculation was that maybe the earth was a big magnetic made of lodestone. The lodestone we find on the surface came from the bowels of the earth, maybe from its magnetic center. From that the iron core magnetic theory was born, but still sort of censored by religion. This was was the abode of hell. But in sciences defense, war is hell, and Mars the god of war is equated with the metal iron. It hasn't really been questioned since then. It has been refined with nickel to keep it in vogue with the better nickel magnets we can make in the lab. But also to add some extra kick to address insulation considerations.

The dogma is so well protected that once flaws are found and can't be just ignored, alternate explanations appear to help protect it from harm. A simple earth formation from a cloud of dust has the problem of iron oxidation like all the minerals in the crust. So we cheat oxidation with asteroids. But are asteroids pure magnets? And would serious collisions with the earth, heating these magnets, sort of mess up their magnetic properties?

Don't get me wrong, the iron core might be true. All I am saying it is not provable, yet is treated like it is a fact of life. This is religious dogma. Just because there is no God involved doesn't exempt the nature of faith in an unprovable. Maybe this theory hangs on until something better appears. But dogma censors all exceptions, so nothing is allowed to change. It is stuck in that transition between religion and science.

The Earth's magnetic field isn't thought to be the effect of magnetized iron, but because of the spinning liquid metal, aka the "dynamo effect."

MDT. Earth has a solid (mainly) iron core inside liquid (mainly) iron outer core. As Earth rotates they move at different rates which generates the magnetic field and causes it to wander and eventually to flip over. The dynamo effect as Pan calls it.

There are no dogmas in science, except Nullius in Verba.

Hello all

Another theory is the rotation of the Earth with a net charge will generate a magnetic field. Whether the charge is positive or negative will determine the polarity of the magnetic field. Zero net charge would mean no magnetic field. Of course there may be some residual magnetic field from the iron core but the temperature at the core is above the Cure temperature for iron.
Space is full of charges either from the Sun or from the local gas cloud. The Sun also flips its magnetic field to so I am wondering if the Sun cycles through bouts of emitting predominantly electrons or protons on the solar ecliptic.

Saltpeter. Science is full of dogmas where speculations are accepted as truths.

Montec. The sun flips it's magnetic field every 11 years like clockwork, which coincides with a solar maximum. As the sun works by fusing hydrogen into helium and emits the by products of that reaction, I would think that what it emits hardly ever changes while it is on a set cycle.

Space at Earth's distance contains maybe ten atoms of hydrogen per cubic cm and other odd particles. I doubt that the charges of this insignificant amount would count.

The Earth is certainly charged, and its rotation would certainly produce an overall magnetic field because of that charge, unless the charged particles for some reason stay stationary as the planet rotates. However, I'd think that field would be far weaker than the dynamo-generated field caused by the convection currents in the core, weaker even than the field induced by the sun's magnetic field. The Earth isn't that strongly charged, and it's not rotating that fast.

Also, I'd expect the charges being lost/gained from either Earth or the sun to quickly settle into an equilibrium, and for the final balance to be determined by the relative masses of electrons vs. protons/heavier nuclei and ions (and in the case of the sun, the energies given to each by the fusion process)...it probably varies somewhat with the amount solar activity, but I'd be very surprised if it ever switched signs. Then there's the tilt with respect to the rotation axis, and all the irregularities in the field...it's pretty clearly generated by the core dynamo.

Hello kanada, et al.

Here is an image from NASA/Ulysses

click to enlarge

Notice that the proton density (positive ions) is higher in the ecliptic band. There are also some spikes in this area but it is not clear if these spikes are long term phenomenon. If these spikes are more or less long term then the Earth's ecliptic path (which has a 100,000 year period) will encounter different mixes of charged particle densities.

Humbled, I bow to your authority.

Eppur si muove.

saltpeter. Galileo might have asked where the proof was if confronted with the big bang, what goes on inside a black hole, superstrings, etc.

So called puzzles of QM like the double slit experiment and quantum entanglement are just parlour tricks as I have shown elsewhere.

PS. Isn't potassium nitrate spelt saltpetre?

Montec. An x-ray view of the sun. By using a device which would normally only detect x-rays and higher energy radiation/particles, we only see the most energetic parts of the sun without the unwanted low energy stuff that we can see with our eyes.

The cooler parts (black) are 5-6,000.C . The hotter parts are notably the sun spots which are magnetic holes in the sun's surface which show the hotter inside of the sun.

How does curie temperature for iron vary with pressure??? Is it possible that under extreme pressure the curie temperature is higher than the temperature of the core. In which case the core could be magnetic. I presume that with increased pressure the atoms would be pressed together more firmly and this might be enough to overcome the thermal agitation.

Is someone able to calculate pressure at earth centre based on average density and gradually decreasing gravity. Acceleration due to gravity at centre will be zero. For first approximation I picture a column of water 4000 miles high surely that would produce a very high pressure???

Pan, Kaneda,

dynamo effect?
Then what about mars? It has an iron core, ( yes I know,, liquid not solid)it spins and yet all most no magnetic field. Has it just not cooled enough yet or did it have one and has lost it?

http://www.sciencedaily.com/releases/2003/...30307071457.htm

This post has been edited by paul h on Dec 10 2007, 11:24 PM