• Question: Why is the Earth's core hot? What caused it to heat up? Is it still heating, or now cooling?

    Asked by dong to Mike, Pip, Tianfu, Tim, Tom on 29 Jun 2012.
    • Photo: Tim Stephens

      Tim Stephens answered on 29 Jun 2012:

      I was under the impression that it’s cooling down all the time. It’s very slow though and will be hot for millions more years. It’s hot because the earth was once a completely molten droplet of rock in space. The crust cooled down, but the heat hasn’t got out from the middle yet.

    • Photo: Tom Lister

      Tom Lister answered on 30 Jun 2012:

      I agree with TIm, I doubt there is a source of heat at the moment, it just takes ages to cool down because it is so big. Not very much is known about the deeper parts of the earth though, not even if it is actually solid.

      The reason it got hot in the first place is from the loss of gravitational energy as all of the matter pulled together when the earth was formed.

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