If magnets are destroyed by heat,then how come the Earth is magnetic?

Question

The Earths core is well hot so how come its magnetism isn't destroyed?

Answer 1

The Earth's magnetic field is created by a dynamo effect that is not understood in great detail. Magnetic fields surround electrical currents as well as magnets and the Earth's magnetic field is thought to be from circulating electric currents within the Earth's core. This is why the heat and molten condition of the core do not destroy the magnetic field.

The Earth's rotation speed is thought to be a significant part of the dynamo effect that creates the magnetic field. Since Venus was found to have no magnetic field, even though it is beleived to have a similar core, the rotation period of Venus of 243 Earth days is believed to be too slow for Venus to develop a dynamo effect.

As the Earth rotates, a charge is likely created by internal friction between layers. This electrical loop current could be great enough to create the dipole magnetic field of earth. This model is described as a geodynamo, similar to an electric generator. This model also fits well with the observation that the Earth's magnetic field has reversed itself over 170 times in Earth history.
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/genwir.html#c1

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magearth.html

Also see:
http://www.sciencenews.org/pages/sn_arch/10_19_96/bob1.htm

Answer 2

There are different kinds of magnets and different reasons for things being magnetic. Most magnets depend on the atoms being lined up together to create or hold a field. When you heat them, the atoms are free to move and lose their orientation, and the field vanishes.

The Earth has minerals in the mantle (called perovskites) that can become powerful magnets when they are compressed, even though they are hot. This may have some bearing on the Earth's magnetic field, although nobody is really sure yet. We still don't know exactly where our magnetic field comes from.

Answer 3

Iron or bar magnets, when heated, have the iron or nickel atoms disoriented. Heat causes them to move and change their alignment with each other, which is thought to be the way they manifest magnetism.

Plasma, which is a very hot form of matter, can also have electromagnetic fields, and the theory about the earth's magnetism is that iron and nickel atoms in very slow, dense magma deep in the earth have their magnetic moments aligned also, giving rise to the earth's magnetic field.

The earth's magnetic field has reversed polarity several times in the past, so we presume it cannot be caused by a solid.

Answer 4

The earths magnetic field is set up by the flow of electric current within the core of the earth (not the poles LOL). The Currie temperature is exceded but the core is Liquid and dynamic.

The exact mechanism is not understood but the rotation of the earth appears to have a large contributing effect.

Answer 5

Earth's magnetic field is formed due to a different electron situation. Stable magnets have domains that line up in a mutual manner so that the extended magnetic lines remain unmovable. In our planet, the magnetic field is due to the rotation of it.

As our planet spins, there are fields of angular force that increase in value as one moves from each pole toward the equator. These forces move in opposite direction to each other (called the Coriolis Effect). When they meet at the plane of the equator, they meet face to face, causing a strong shearing action through the plane where they meet. Within our planet is a vast plasma state. This is a condition where the outer shells of electrons no longer are attached a particular atom. When a strong shearing action passes through a plasma, a magnetic field forms at right angles to this force. It is for this reason we have north and south poles - they are opposites in energy value and formation. Were our planet to reverse its spin state, then the north and south poles would change places.

Answer 6

I didn't know that heat destroys magnets but remember that the magnetic fields come from the north and south poles which are cold.

Answer 7

No one really understands how the Earth's magnetic field is generated. It's an outstanding question, and if you can figure it out you will probably earn a Nobel in physics.

Answer 8

inner core is made of nickel-iron...outer core is made of molten iron, among other things...temperature around 9-11,000 degrees F. inner core spins rapidly...superheated metal, spinning quickly, generates an electromagnetic field.