Earth's inner core

This article is about the geological center of the planet. For the geographical meaning of the term "center of the Earth", see Geographical centre of Earth.
For broader coverage of this topic, see Internal structure of Earth § Core.

The internal structure of Earth
Schematic view of Earth's interior structure.
  1.   continental crust
  2.   oceanic crust
  3.   upper mantle
  4.   lower mantle
  5.   outer core
  6.   inner 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 1,220 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. ^ https://www.calacademy.org/explore-science/from-core-to-crust-defining-earths-layers