Earthed - What causes the mangetic fields around the planet earth?

What causes the mangetic fields around the planet earth?

I was told it has to do with something in the center of the planet.

Can someone please give me a better but yet short discription? Thanks.

Public Comments

Yeah...The molten iron core of the earth is responsible for the magnetic field around the earth.
Currents in the molten iron core. Iron conducts electricity, and when it flows, magnetic fields are created.
This might help - look under the "Origins" section.

http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html
The force forms within our planet due to its spin. Angular momentum increases as one moves from either pole toward the equator. This increase of rotation causes the "Coriolis Effect" to form, which force causes water and winds to move in opposite directions in either hemisphere. The mass and energy move in the same direction in the northern hemisphere while in the southern one the energy of rotation moves against that of mass movement. This resistance causes a 25' rise in mass at the equator in the southern hemisphere that is not in the northern one.

When these forces meet through the plane of our planet's equator they form a strong shearing action. When this occurs within the area of our plant's plasma, an electric field is generated, which in turn forms a magnetic one at right angles to it. It is obvious, when considering a mass as large as a solar planet, why the fields are negative and positive.
The earth has a rotating core of nearly pure iron about the size of the moon. Ordinarily, liquid iron can not be magnetized, but the core is under such enormous pressure it seems that it is possible. The earth formed by the gradual accumulation of billions of chunks of debris orbiting around the sun. These chunks came together because of gravity. Iron was randomly distrubuted amoungst all the material, but at one point in time all the chunks melted. Most of the heavier iron then accumulated at the center of the earth, where it exists today. Lighter material like silicon, oxygen and carbon floated to the top. This formed the crust of the earth. The earth's iron core also forms a shield to deflect charged particles coming from the sun. This stream of particles is called the "solar wind". One can see the effect at earth's two poles. This is where the magnetic field is the densest. The field causes the particles to glow, and this is how the "aurorae borealis" forms. Mars once had an atmosphere, warmer temperatures and an ocean. It had a liquid iron core and magnetic field. However, Mars is smaller than earth, and the iron core solidified. This extinguished its magnetic field. The solar wind then stripped away most of the air and water on Mars, leaving it a frozen desert. Finally, the "poles" are the two opposite points on earth's surface where the magnetic lines for force re-enter the earth. They are equivalent to the poles on a magnet. The exact location of these poles is not the geographic north and south poles, however. The magnetic poles also can move, and the north pole is now somewhere in arctic Canada. Over the last several decades, the strength of the magnetic field has begun to fluxuate. The poles regurarly reverse themselves every 100 thousand years or so. It is estimated that in the next thousand years, the poles will have completely reversed. This is known because volcanic lava is magnetised by the earth's field before it hardens. Bands of lava oppositely magnetised occur across the floor of the atlantic ocean. A great fault line generates successive waves of lava and this pushes the continents apart. The bands of magnetic lava helped prove the theory of continental drift.
If you want to know the real "origins" of the Earth magnetic field and why some planets have them while some do not, see:

http://www.geocities.com/franklinhu/earthmag.html

While the geo-dynamo theory of Earth magnetism may be correct, it doesn't explain how it sustains itself or what controls the north/south polarity.

I think that the Earth's atmostphere plays a role in sustaining and directing the main magnetic field. Air currents carry ionized charges through the winds and these effectively create a current runnning around the Earth which initializes the main geo-dynamo. It also controls the direction. Evidence shows that in the past when winds blew primarily east-west instead of west-east (as they are today), that the magnetic poles flipped.