Internal structure of Earth

The internal structure of Earth is how Earth is built inside, with different layers that each have special features. These layers are an outer silicate crust, a soft layer called the asthenosphere, a solid mantle, a liquid outer core, and a solid inner core. The movement of the liquid outer core creates Earth's magnetic field, which keeps us safe from harmful space rays.

Scientists learn about Earth's inside by studying the land and oceans, looking at rocks from volcanoes, and watching seismic waves that move through the planet. They also study Earth's gravitational and magnetic fields, and do experiments with rocks under very high pressure and temperature. This helps us understand how our planet works and why it acts the way it does.

Global properties

We can learn about Earth by studying how its gravity pulls on objects. Scientists measure this pull to find out how much Earth weighs. They also watch how satellites move around Earth to help calculate its mass. Through careful experiments, they have found that Earth’s average density is 5.515 g/cm³. Earth’s mass is about 6×10²⁴ kg.

Note: In chondrite model (1), the light element in the core is assumed to be Si. Chondrite model (2) is a model of chemical composition of the mantle corresponding to the model of core shown in chondrite model (1).

Layers

The Earth is made up of several layers, each with its own special features. These layers include the crust, which is the thin outer layer where we live, and the mantle, a thick layer below the crust made of hot, flowing rock. Deep inside the Earth, there is a liquid outer core and a solid inner core. The movement of the liquid outer core helps create Earth's magnetic field, which keeps us safe from harmful space rays.

The structure of Earth can be studied by looking at how it behaves in different ways. It is divided into layers such as the lithosphere, asthenosphere, mesospheric mantle, outer core, and inner core. Chemically, it is divided into the crust, upper mantle, lower mantle, outer core, and inner core. These layers are found deeper and deeper below the surface.

Earth's crust varies in depth from 5 to 70 kilometres and is the outermost layer. The thinner parts under the oceans are called oceanic crust, while the thicker parts under continents are called continental crust. The mantle, the thickest layer, extends to a depth of 2,890 kilometres. It is made of hot, flowing rock and is split into an upper and lower mantle.

Earth's outer core is a fluid layer about 2,260 kilometres thick, made mostly of iron and nickel. Below this lies the solid inner core, discovered in 1936, which is mainly made of iron and nickel. The core helps create Earth's magnetic field, which is important for protecting life on our planet.

Seismology

Main article: Seismology

Scientists learned about Earth's layers by watching waves from earthquakes. These waves move faster or slower in different layers, and they bend and bounce like light. This helps us learn what Earth is made of inside.