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Earth's magnetism and Sun's temperature

by bonekeeper
Tags: corona, earth, magnetism, sun, surface
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Sep19-08, 08:14 AM
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Hello everybody:

I've got a few questions that I could not find answers to, so perhaps someone on this forum can help me out:

1) If a magnet loses it's magnetism when heated, and magnetism is caused when electrons are aligned in a specific way, how come the Earth's magnetic field is possible, supposing it would be hard to have any coherent electron state in such environment ? Overheated iron & other stuff very hot and probably spinning around, etc... how can electrons keep themselves organized ?

2) It is said that the Sun's core temperature is ~15.7106 K, very hot, while the surface temperature is 5,778 K (hot) and the corona temperature ~5106 K. If sun's temperature comes from its core, then how come that the surface is supposedly colder than the corona, if it is closer to the core than the corona ? So it seems that the core is very hot, the surface is hot, and the corona (farther away) is very hot too, which doesn't make much sense, unless there's another principle at work that I don't know of.

Thanks !
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Jonathan Scott
Sep19-08, 09:38 AM
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P: 1,164
It's a bit confusing asking two questions in one thread. It would probably have been better to ask them separately.

The Earth's magnetism is thought to be described by dynamo theory, involving electric currents and the flow of molten iron. It is not like the magnetism of a static iron magnet.

The question of why the corona is so much hotter than the surface of the sun is not fully resolved. Temperature is related to the average kinetic energy per particle. It appears that some effect (presumably electromagnetic) in the corona accelerates particles to very high speeds, effectively giving rise to a very high temperature.

For this sort of basic question, I'd recommend starting with Wikipedia or a general search on Google, as you'll get answers quicker that way.

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