Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: thedoc on 11/07/2016 16:03:38

Title: How does the Earth's core stay hot?
Post by: thedoc 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?

Keep up the good work, love the show!
Asked by Jan F

Visit the webpage for the podcast in which this question is answered. (http://www.thenakedscientists.com/HTML/podcasts/naked-scientists/show/20160705/)

[chapter podcast=1001386 track=16.07.05/Naked_Scientists_Show_16.07.05_1005366.mp3](https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.thenakedscientists.com%2FHTML%2Ftypo3conf%2Fext%2Fnaksci_podcast%2Fgnome-settings-sound.gif&hash=f2b0d108dc173aeaa367f8db2e2171bd) ...or Listen to the Answer[/chapter] or [download as MP3] (http://nakeddiscovery.com/downloads/split_individual/16.07.05/Naked_Scientists_Show_16.07.05_1005366.mp3)
Title: How does the Earth's core stay hot?
Post by: RD on 15/11/2010 03:17:32: Heat released by the decay of radioactive elements like Uranium keep it toasty.

Quote
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
Title: How does the Earth's core stay hot?
Post by: Bass 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.
Title: How does the Earth's core stay hot?
Post by: frethack 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.
Title: How does the Earth's core stay hot?
Post by: RD on 15/11/2010 21:17:29: Quote from: RD on 15/11/2010 03:17:32
Quote
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 (http://en.wikipedia.org/wiki/Earth_tide#Body_tide) adding heat via deformation.

The interaction of the magnetic fields of Earth and Sun as they rotate/orbit, (cf magnetic brake (http://en.wikipedia.org/wiki/Linear_eddy_current_brake))
Title: How does the Earth's core stay hot?
Post by: JimBob 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.
Title: How does the Earth's core stay hot?
Post by: Airthumbs 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. [>:(]
Title: How does the Earth's core stay hot?
Post by: Farcanal on 19/04/2011 02:07:24: Quote from: Airthumbs 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. [>:(]
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.
Title: How does the Earth's core stay hot?
Post by: Geezer on 19/04/2011 10:21:20: Quote from: Farcanal on 19/04/2011 02:07:24
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"?
Title: Hear the answer to this question on our show
Post by: thedoc 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. (http://www.thenakedscientists.com/HTML/podcasts/naked-scientists/show/20160705/) Alternatively, [chapter podcast=1001386 track=16.07.05/Naked_Scientists_Show_16.07.05_1005366.mp3](https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.thenakedscientists.com%2FHTML%2Ftypo3conf%2Fext%2Fnaksci_podcast%2Fgnome-settings-sound.gif&hash=f2b0d108dc173aeaa367f8db2e2171bd) listen to the answer now[/chapter] or [download as MP3] (http://nakeddiscovery.com/downloads/split_individual/16.07.05/Naked_Scientists_Show_16.07.05_1005366.mp3)