Earths core

The topic Earth's core is discussed in the following articles:

chemical composition

  • TITLE: chemical element
    SECTION: The Earth’s core
    The evidence for the composition of the core is all indirect because no means have yet been devised for directly sampling the deep interior of the Earth. The moment of inertia of the Earth indicates that there is a concentration of mass around the centre, and seismic data have shown that below the Wiechert–Gutenberg Discontinuity the density of the material is high, ranging upwards from...
  • TITLE: chemical element
    SECTION: Early history of the Earth

Earth’s interior

  • TITLE: Earth (planet)
    SECTION: The interior
    With a radius of almost 3,500 km (2,200 miles), Earth’s core is about the size of the entire planet Mars. About one-third of Earth’s mass is contained in the core, most of which is liquid iron alloyed with nickel and some lighter, cosmically abundant components (e.g., sulfur, oxygen, and, controversially, even hydrogen). Its liquid nature is revealed by the failure of shear-type seismic waves...

geomagnetic mechanism

  • TITLE: geomagnetic field (geophysics)
    SECTION: The geomagnetic dynamo
    Thermal heating in the core is the process that drives fluid motion. For many years it was thought that this heating was caused by radioactive elements dissolved in the liquid core. Recent work suggests that freezing of the liquid core is more important. Seismic studies have shown that the centre of the Earth is a solid sphere of iron with an approximate radius of 1,200 kilometres. This sphere...

ocean formation

  • TITLE: seawater
    SECTION: The early oceans
    ...ago. Heating of this initially cool unsorted conglomerate by the decay of radioactive elements and the conversion of kinetic and potential energy to heat resulted in the development of a liquid iron core and the gross internal zonation of Earth. It has been concluded that formation of Earth’s core took about 500 million years. It is likely that core formation resulted in the escape of an...


  • TITLE: high-pressure phenomena (physics)
    ...Objects in the deepest trench of the Pacific Ocean are subjected to about 0.1 GPa (roughly 1,000 atm), equivalent to the pressure beneath a three-kilometre column of rock. The pressure at the centre of the Earth exceeds 300 GPa, and pressures inside the largest planets—Saturn and Jupiter—are estimated to be roughly 2 and 10 TPa, respectively. At the upper extreme, pressures...

scientific exploration

  • TITLE: Earth exploration
    SECTION: Conclusions about the deep Earth
work of


  • TITLE: Sir Harold Jeffreys (British astronomer and geophysicist)