The core

  1. why is the core of our earth so hot? what causes it to be so? and why some other stars and planets like neptune/uranus (i forgot) does no have such a hot core? and what purpose does the molten core of our earth serve?
  2. jcsd
  3. drag

    drag 1,341
    Science Advisor

    Greetings !

    Welcome to PF alchemist !
    Friction and nuclear decay of the heavier
    elements that "sank in" during Earth's formation.
    In stars there's nuclear fusion of elements in
    the center. They're extremely hot inside and

    As for other planets, I believe that the same
    thing happens there too, but the specifics
    depend on the planet's formation and elements
    present. I'm not sure about the way it works
    in gas giants though.

    I'm not sure what you mean by - "what purpose does
    the molten core... serve ?". It's just there.

    Live long and prosper.
  4. russ_watters

    Staff: Mentor

    And don't forget pressure.
  5. Janus

    Janus 2,479
    Staff Emeritus
    Science Advisor
    Gold Member

    Initally, the heat came from the energy of the material as it condensed to form the Earth. Additional heat is added by the radioactive elements as already mentioned. As the Surface of the Earth cooled, and the Crust formed, the molten interior was surrounded by a natural insulator. This insulation, in the form of solid rock, traps the heat inside pretty effectively.

    The gas giants don't have a solid surface, and as such, can lose heat faster.
  6. Janus
    Also, radioactive elements tend to be of higher atomic number, more common with terrestrial planets.

    Is lava significantly more radioactive than the crust in general?
  7. It's similar to the way the core of a star forms (plus pressure)

    What about the movie? Seems silly to me.
  8. Phobos

    Phobos 1,982
    Staff Emeritus
    Science Advisor
    Gold Member

    Purpose? Like the existential purpose of being? No answer there.

    But, the flow of the iron in the core creates a magnetic field for the Earth. The Earth's magnetic field reduces the amount of cosmic rays and ionized particles reaching the Earth's surface (good for us). It also creates the aurorae at the north and south poles.
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