The earth is divided into four main layers: the inner core, outer core, mantle, and crust.

The core is the centre of the earth and is made up of two parts: the liquid outer core and solid inner core. The outer core is made of nickel, iron and molten rock.

Mental is the middle layer of the earth lies between crust and core. The average thickness of this layer is 100 to 2900 km. Silica and magnesium elements predominate in this layer so it is known as SIMA.

Unlike the mineral-rich crust and mantle, the core is made almost entirely of metal—specifically, iron and nickel. The shorthand used for the core’s iron-nickel alloys is simply the elements’ chemical symbols—NiFe. Elements that dissolve in iron, called siderophiles, are also found in the core.

Earth’s interior is generally divided into three major layers: the crust, the mantle, and the core.

The crust is the outermost layer of the Earth. Except in the crust, the interior of the Earth cannot be studied by drilling holes to take samples. Instead, scientists map the interior by watching how seismic waves from earthquakes are bent, reflected, sped up, or delayed by the various layers.

Water forms some features of Earth’s surface such as rivers, oceans, beaches and lakes. Other surface features, such as mountains, earthquakes and volcanoes, are formed when large pieces of the Earth’s outer layer move slowly by plate tectonics.

The thermo- in thermosphere means “heat.” Even though the air in the thermosphere is thin, it is very hot, up to 1,800°C. This is because sunlight strikes the thermosphere first. Nitrogen and oxygen molecules convert this energy into heat. Despite the high temperature, you would not feel warm in the thermosphere.

Because there are relatively few molecules and atoms in the thermosphere, even absorbing small amounts of solar energy can significantly increase the air temperature, making the thermosphere the hottest layer in the atmosphere.

The exosphere is the highest and top layer of the Earth’s atmosphere. It marks the edge of space. There are very few molecules in this layer. The lightest atmospheric gases such as hydrogen and helium exist throughout the exosphere.

Functions of the Exosphere Its functions to act as a transitional medium to a zone under the influence of gravity. It also helps the atoms to escape from the atmosphere to outer space. Unlike other atmospheric layers, it is the only layer of the atmosphere that has a definite shape.

Most gas particles in the exosphere zoom along curved paths without ever hitting another atom or molecule, eventually arcing back down into the lower atmosphere due to the pull of gravity. However, some of the faster-moving particles don’t return to Earth – they fly off into space instead!