What is the temperature of Earth’s core?

In terms of its size, the Earth looks very modest. Even among the closest space neighbors in the Solar System by this indicator, it is “average”, not even in the top three “leaders” – the fourth of eight. However, the uniqueness of our planet is not at all in its mass, and not in the extremely high temperature of the core. The Earth is still the only ecosystem known to us, which became the cradle of civilization.

The structure of the Earth

In shape, the Earth is close to a sphere – the equatorial and polar diameters are equal to 12754 and 12711 kilometers, respectively. If you mentally make a slice from its surface to the center, we see a real “layer cake” of three main layers – the Earth’s crust (up to 75 km thick), the mantle (about 2800 km) and the core. In turn, the Earth’s core consists of the outer and inner cores, which are 2300 and 1200 km thick, respectively.

However, the “solid” Earth has a continuation, without which it would never be the Earth we know – the atmosphere that goes to the sky.

This is also, in essence, a “layer cake”, only already celestial. The lower part of the atmosphere (up to about 20 km) is the troposphere. Above (up to 50 km) is the stratosphere. Having risen another 30 km, we will find ourselves in the mesosphere – the “anteroom” of the near space. The near space – thermosphere extends at a height from 80 to 700 km. To the boundary of the Earth’s atmosphere – exosphere we will have to overcome 10000 km.

History of the discovery of the Earth’s core

The most interesting object of scientific research was the Earth’s core. For the first time, the hypothesis of its existence was expressed by the German geophysicist Emil Wichert in 1897.

In the course of research, he came to the conclusion that the Earth consists of several layers, and the difference between the density of rocks of the surface layer and the average density of the Earth can mean only one thing – the presence of her in the center of the heavy iron core.

After almost 30 years, French geophysicist Benoit de Libriz on the basis of measurements of earthquakes recorded 800 km from the epicenter, noticed that this distance seismic waves passed through the Earth somewhat faster than the original assumptions, from which he concluded – deep in the bowels of the Earth is a layer that accelerates the propagation of waves.

Later, Libriz’s colleague, British geophysicist David Pipes, discovered Z-waves travel through both solid and liquid media, including the Earth’s core.

Why the Earth’s core is solid

As a result of subsequent studies, scientists were able to establish the temperature of the Earth’s core – from 5427 to 5927 °C, which roughly corresponds to the average temperature on the surface of the Sun (about 5500 °C) and even slightly exceeds it. The reason for this “lag” – in the dark spots on the Sun, where the temperature of plasma “only” 3727 °C.

Also became known and the composition of the inner core of the Earth, which is an alloy of iron and nickel. At the same time remained a mystery, as at temperatures hotter than the Sun, the core remains solid. For reference, iron has a melting point of 1538 °C and nickel 1453 °C.

Why does this happen? The point is that the center of the Earth is a unique natural reactor, where its core is under the “descent” of a gigantic, extreme pressure – 350 gigapascals or 3.5 million atmospheres. It is this pressure that stabilizes the crystal lattice of the iron-nickel core and ensures its hardness. Unlike the inner core, the Earth’s outer core is liquid.

Why the Earth’s core is hotter

For the past few decades, nuclear physicists have been fighting for access to controlled fusion, and in fact, for the creation of the Earth’s Sun. Meanwhile, the non-man-made nuclear reactor is literally under our feet at a depth of about 7000 kilometers.

It was “launched” about 4.5 billion years ago, when our planet was formed. But even such a long “operation” practically did not affect the amount of heat released by the Earth’s core – nuclear decay inside it still generates energy with a power of up to 20 terawatts or 20 billion kW⋅h.

And yet the Earth’s reactor is slowly cooling down – by about 100 °C every billion years. At the same time, the loss of primary heat, although not completely, is compensated for by the energy from friction and thermonuclear reaction, which inhibits the processes of natural cooling.

There is no consensus in the scientific community on the prospects of the “working resource” of the Earth’s core. However, if the theory of maintaining thermal balance is correct, there is nothing to worry about – the Earth has at least a few tens of billions of years in reserve. By the way, the Sun may go out much earlier.

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