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3.19: Earth's Core

  • Page ID
    5357
  • Is this what the core looks like?

    Yes! The outer core, anyway. The outer core is liquid metal, like in this photo. Of course, the metal is under an incredible amount of pressure.

    Core

    The dense, iron core forms the center of the Earth. Scientists know that the core is metal. The inner core is solid, and the outer core is molten. Here are some of the reasons they know this:

    • Metallic meteorites are thought to be from the same type of material that is found at the core (Figure below).

    An iron meteorite is the closest thing to the Earth’s core

    An iron meteorite is the closest thing to the Earth’s core that we can hold in our hands.

    • Scientists calculate Earth's density from the planet's rotation. To match the total density, the inner layers must be denser than the outer layers. They must be as dense as metal.
    • Seismic waves show that the outer core is liquid. The inner core is solid.
    • For there to be a magnetic field, there must be liquid metal. The metal must be convecting. If the core did not have convecting metal, there would be no magnetic field.

    Summary

    • Density calculations show that Earth's core is metal.
    • Seismic waves show that the inner core is solid and the outer core is liquid.
    • Metallic meteorites and the magnetic field are also clues about the makeup of the core.

    Review

    1. What evidence is there that Earth's core is metal?
    2. What evidence is there that the outer core is molten?
    3. Why does Earth have a magnetic field?

    Explore More

    Use this resource to answer the questions that follow.

    1. What layers does the core have within it according to the study described in this video?
    2. How deep is the core? What is its temperature?
    3. What clues to researchers use to “see” what is in Earth’s interior?
    4. What was the inner core thought to be previously?
    5. What do scientists now think is inside the core? How big is it?
    6. What is the interior made of? How do scientists know this is different from the material outside of it?
    7. How are crystals aligned in the inner inner and outer inner cores?
    8. Why is this information important?
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