The Earth

Layers of the Earth: Structure of the Planet Earth

Layers of the Earth: structure of the planet Earth

Earth is roughly shaped like a sphere with a diameter of about 12,730 km.

The structure of the Earth consists of several layers formed over millions of years, distinguished by chemical or geological properties.

In the center is an inner core with a radius of about 1,250 km, which is mainly made up of iron and nickel. Next comes the outer core (consisting mainly of iron) with a thickness of about 2200 km. Above it are 2,900 km of a viscous mantle consisting of silicates and oxides, and even higher - a rather thin solid. It is also composed of silicates and oxides, but it is enriched in elements that are not found in mantle rocks.

The interior of the Earth can be divided into layers based on its mechanical (particularly geological) or chemical properties.

According to the mechanical properties, the lithosphere, the asthenosphere, the mesosphere and the inner and outer nuclei are distinguished.

According to its chemical properties, the Earth can be divided into Earth's crust, upper and lower mantle, and inner and outer core.

Schematic representation of the internal structure of the Earth:Layers of the Earth: structure of the planet Earth

  1. Continental crust composed of the mainland.
  2. Oceanic crust composed of rivers, seas, oceans, etc.
  3. Upper mantle.
  4. Lower mantle.
  5. Outer core that is in a liquid state.
  6. Inner core that is in solid state.

What Are the Inner Layers of the Earth?

The inner layers of the earth from the surface inward are the earth's crust, mantle, and core.

Core of the Earth

The inner core is the innermost layer of the Earth.

Seismic wave measurements show that the core is divided into two parts:

  • A solid inner core with a radius of approximately 1,220 km.
  • A liquid outer core with an approximate radius of 3400 km. The outer core is in a liquid state due to high temperatures. It is responsible for the Earth's magnetic field.

Mantle of the Earth

The Earth's mantle extends to a depth of 2,890 km, which makes it the thickest layer on Earth. The pressure in the lower mantle is approximately 140 GPa.

The mantle is made up of silicate rocks rich in iron and magnesium in relation to the overlying crust. The high temperatures in the mantle make the silicate material plastic enough to allow convection of the material in the mantle, which emerges to the surface through faults in the tectonic plates.

It is divided into two parts:

  • Top: the top is solid and there are the tectonic plates, which are rigid plates of rock.
  • Bottom part: this part is in a liquid state due to high temperatures. This molten matter is known as magma.

Earth Crust

The Earth's crust is the layer on which we live and it is the thinnest on the planet.

Below the crust is the mantle, which differs in composition and physical properties: it is more dense, it contains mainly refractory elements.

The earth's crust is divided:

  • The oceanic crust or hydrosphere is found at the bottom of rivers, lakes, seas, and oceans. It is between 5 and 12 kilometers thick.
  • The continental crust or lithosphere is the layer that occupies the rest of the surface. The thickness of this layer is approximately eighty kilometers.

What Are the Outer Layers of the Earth?

The outer layers of the Earth are made up of gases. The set of all of them is what we know by atmosphere and is close to a thousand kilometers thick.

  • Troposphere: is the layer that is in contact with the surface of the Earth and is the gaseous layer that contains the air we breathe and has a thickness of between ten and twelve kilometers. This layer works as a thermal regulator, softening the temperature contrast between day and night thanks to the greenhouse effect that it naturally generates.
  • Stratosphere: it is above the troposphere and is about 50 km thick. Unlike what happens with the other layers, in the stratosphere the temperature increases with altitude due to the ozone layer that absorbs solar radiation. It is the height at which airplanes fly.
  • Mesosphere: it is about thirty kilometers thick and is the coldest layer on earth. The mesosphere destroys the vast majority of asteroids and meteorites that impact with it.
  • Ionosphere: The ionosphere contains a large amount of electrical particles due to terrestrial radiation.
  • Exosphere: it is the outermost layer of the atmosphere. It is the layer that softens the amount of solar energy that the Earth receives. In this layer the satellites are placed.

Published: September 28, 2021
Last review: September 28, 2021