Earth's inner core

For broader coverage of this topic, see Internal structure of Earth § Core.

Earth's inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,230 km (760 mi), which is about 20% of Earth's radius or 70% of the Moon's radius.[1][2]

There are no samples of the core accessible for direct measurement, as there are for Earth's mantle.[3] The characteristics of the core have been deduced mostly from measurements of seismic waves and Earth's magnetic field.[4] The inner core is believed to be composed of an iron–nickel alloy with some other elements. The temperature at its surface is estimated to be approximately 5,700 K (5,430 °C; 9,800 °F), about the temperature at the surface of the Sun.[5]

The inner core is solid at high temperature because of its high pressure, in accordance with the Simon-Glatzel equation.[6]

  1. ^ Cite error: The named reference monner2010 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference eng1974 was invoked but never defined (see the help page).
  3. ^ "Earth's Interior". National Geographic. 18 January 2017. Archived from the original on 11 April 2021. Retrieved 17 November 2021.
  4. ^ Cite error: The named reference alle1995 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference alf2007 was invoked but never defined (see the help page).
  6. ^ "From Core to Crust: Defining Earth's Layers | Exploring Earthquakes".
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