Talk:Planetary core

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It would be great if as a part of this topic, someone could explain the methods scientists used to determine what the Earth's core consists of?

[edit] What "powers" the core?

Well, I came here looking for this information, so I'll use the talk page as to suggest what should be put in. My primary question is what "powers" the core? Originally the compression of matter and gravity generated the heat, but now it is hundreds of millions of years later and it still hasn't cooled, and the magnetic strength of the Earth (caused by an ever rotating iron core) is still about 90% as it once was, which IMO, even jumps up in strength sometimes, ie. ice age, and isn't more of losing energy than preparing for a magnetic pole switch.

Is it the Earth's orbit around the sun, transferring the momentum to the Earth's core? Or the sun's slow orbit around other stars, and with the galaxy et al powering all this? Or the sun's magnetic field? What then? -- Natalinasmpf 14:56, 11 Mar 2005 (UTC)

• Well, I'm no hard scientist here, but I'd say the sun, pressure, and in a general sense, nothing. First off, what do you mean by "powers?" The planet isn't really doing anything then falling through space. It's still liquid and hot down in the center, but where do you think this would go? The planet radiates heat out into the universe, but the sun also warms it. If the question is why is it hotter in the center then it is right here? Well then I would say that pressure, although I'd have a hard time justifying that. Something to the effect that as pressure increases, temperature increases. Now the earth isn't nearly big enough to cause a chain reaction like the sun or a black hole. Although I heard that Jupiter is so big it gives off more heat then it recieves. But I believe you are thinking about the heat death of the universe. That starts around 10^14. We've been around for about 10^9. You know, probably-ish. So yeah, earth isn't powered by anything and is winding down. 64.238.49.65 20:57, 31 October 2006 (UTC)

• • I'm a geophysicist who studies the core and deep Earth. The core is still hot from its initial formation, and it cools very slowly because the only way heat escapes is through the slow creeping convection motion of the overlying rocky mantle. The mantle is solid, but over long time scales it behaves as a very very high viscosity fluid. The core was very hot initially because of the release of gravitational potential energy in separating it from its silicate rocky part. The inner core is solid and slowly freezing from the outer liquid part, and grows about 1 km every million years. The rate of cooling of the core determines whether or not convection can occur inside the outer liquid part, and this process is thought to be the only way for generating Earth's magnetic field. So yes, Earth's magnetic field is powered by cooling of the core, but if the core were to have cooled too fast it would be frozen and we'd have no magnetic field. This gives us constraints on the thermal evolution of Earth's interior. —Preceding unsigned comment added by 24.84.196.231 (talk) 04:52, 22 October 2007 (UTC)

[edit] history

I'm curious about the history of scientists discovering that planets have a core, and how they came about to that conclusion --geekyßroad^{. meow?} 05:33, 22 October 2007 (UTC)