StringJunky

Earth's internal heat from gravitational sources and rotation

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Posted (edited)

Reading up on the heat sources that cause its interior temperatures, I'm a bit puzzled by this:

Quote

The next source of heat is gravitational pressure. The Earth is under immense pressure due to the tidal forces exerted by the Sun, the Moon, and the other planets in the Solar System. When you include the fact that it is also rotating the Earth’s core is under immense pressure. This pressure basically keeps the core hot in the same way as a pressure cooker. It also helps to minimize the heat it loses.  https://www.universetoday.com/75895/why-is-the-center-of-the-earth-hot/

How does the external forces from the other astronomical bodies and its rotation cause 'pressure'? It seems counterintuitive because the forces are from outside and the Earth's rotation will cause a centrifugal.action. At first sight, it seems everything mentioned would seek to pull it apart. My commonsense says that the Earth''s own gravity would centripetally create the necessary pressure but it's not mentioned.

Edited by StringJunky

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Posted (edited)
11 minutes ago, Sensei said:

You should read article about Jupiter moon, Io. In this body heating is much more impressive.

https://en.wikipedia.org/wiki/Tidal_heating_of_Io

https://en.wikipedia.org/wiki/Tidal_heating

 

Cheers. So, it's the small distortions of the Earth's shape, exerted by the gravitational forces of the other bodies, generate friction within the Earth's structure?

Edited by StringJunky

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Posted (edited)

I was wondering about that as well. I had learned about it a couple months ago. Notice how plastic gets warm whenever you bend it or chew it.

Edited by NimrodTheGoat

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On 5/14/2018 at 8:11 PM, StringJunky said:

Reading up on the heat sources that cause its interior temperatures, I'm a bit puzzled by this:

How does the external forces from the other astronomical bodies and its rotation cause 'pressure'? It seems counterintuitive because the forces are from outside and the Earth's rotation will cause a centrifugal.action. At first sight, it seems everything mentioned would seek to pull it apart. My commonsense says that the Earth''s own gravity would centripetally create the necessary pressure but it's not mentioned.

It's kind of a crappy article (it calls radioactive decay "fission", and thermal energy "heat", for example), so one can't discount poor wording of the explanation. 

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23 minutes ago, swansont said:

It's kind of a crappy article (it calls radioactive decay "fission", and thermal energy "heat", for example), so one can't discount poor wording of the explanation. 

Right. I'll take it with a pinch of salt then and read around a bit more.

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Get a hold of this Cambridge University Press book

Thermodynamics of the Earth and Planets

Albero Patino Douce

 

It contains a wealth of information about the contributions to the energy budget of not only the terrestrial type planets but others (gas giants) as well.

In the case of the Earth a major contributor was the process known as differentiation.
That is the migration of the heavier material towards the interior, eventually forming the core.

 

Here is an extract with some facts and figures.

differentiation1.jpg.dc7a3687232b760cbc47fbd9b6c175c4.jpg

 

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