How does the Earth's core stay hot?

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Offline thedoc

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How does the Earth's core stay hot?
« on: 11/07/2016 16:03:38 »
I believe the Earth has a solid core made of Nickel and Iron at a temperature of several thousand DegC (correct me if I'm wrong).  Why does this core keep its temperature? Why did the core not cool down over the last 3-4 billion years or so?

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Asked by Jan F


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[chapter podcast=1001386 track=16.07.05/Naked_Scientists_Show_16.07.05_1005366.mp3]  ...or Listen to the Answer[/chapter] or [download as MP3]

« Last Edit: 11/07/2016 16:03:38 by _system »

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Offline RD

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How does the Earth's core stay hot?
« Reply #1 on: 15/11/2010 03:17:32 »
Heat released by the decay of radioactive elements like Uranium keep it toasty.

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The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years
http://en.wikipedia.org/wiki/Uranium


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Quentin Williams, associate professor of earth sciences at the University of California at Santa Cruz offers this explanation:

There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.
http://www.scientificamerican.com/article.cfm?id=why-is-the-earths-core-so
« Last Edit: 15/11/2010 03:23:27 by RD »

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Offline Bass

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How does the Earth's core stay hot?
« Reply #2 on: 15/11/2010 05:31:28 »
Potassium is much more abundant than either uranium and thorium- the decay of radioactive isotopes of Potassium likely contributes much of the radioactive heat in the core and mantle.
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Offline frethack

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How does the Earth's core stay hot?
« Reply #3 on: 15/11/2010 17:30:27 »
Also rock is a very poor conductor of heat, so convenction and advection of heat is extraordinarily slow.
frethack

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Offline RD

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How does the Earth's core stay hot?
« Reply #4 on: 15/11/2010 21:17:29 »
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There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.
http://www.scientificamerican.com/article.cfm?id=why-is-the-earths-core-so

just thought of two other possible sources of heat input to Earth...

Body tides adding heat via deformation.

The interaction of the magnetic fields of Earth and Sun as they rotate/orbit, (cf magnetic brake)

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Offline JimBob

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How does the Earth's core stay hot?
« Reply #5 on: 10/04/2011 23:03:26 »
Physicist calculate that the core of the earth is 500░ C cooler than it was 2.5 billion years ago.
The mind is like a parachute. It works best when open.  -- A. Einstein

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Offline Airthumbs

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How does the Earth's core stay hot?
« Reply #6 on: 11/04/2011 04:47:36 »
Your all forgetting one thing, apparently 86% of us think that there is this red dude [:(!] with a trident and horns who lives down there and supposedly he is going to keep it eternally hot, no one told him about the entropic nature of the universe!

Sorry I apologise for my completely non scientific response to your valid question but I am just sick and tired of Intelligent Design.   [>:(]
Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction. (Einstein)

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Offline Farcanal

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How does the Earth's core stay hot?
« Reply #7 on: 19/04/2011 02:07:24 »
Your all forgetting one thing, apparently 86% of us think that there is this red dude [:(!] with a trident and horns who lives down there and supposedly he is going to keep it eternally hot, no one told him about the entropic nature of the universe!

Sorry I apologise for my completely non scientific response to your valid question but I am just sick and tired of Intelligent Design.   [>:(]
Aye! The world is full of whacko's!

The core is slowly cooling down but don't worry - it will still stay hot enough to see us out.

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Offline Geezer

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How does the Earth's core stay hot?
« Reply #8 on: 19/04/2011 10:21:20 »
The core is slowly cooling down but don't worry - it will still stay hot enough to see us out.

Don't you mean "see us oot"?
There ain'ta no sanity clause, and there ain'ta no centrifugal force Šther.

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Offline thedoc

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Hear the answer to this question on our show
« Reply #9 on: 11/07/2016 16:03:38 »
We discussed this question on our  show































































































































Kat Arney put this to Professor Marian Holness, geologist from the University of Cambridge...































































































































[Transcript to follow]































































































































Click to visit the show page for the podcast in which this question is answered. Alternatively, [chapter podcast=1001386 track=16.07.05/Naked_Scientists_Show_16.07.05_1005366.mp3] listen to the answer now[/chapter] or [download as MP3]
« Last Edit: 11/07/2016 16:03:38 by _system »