What is in the center of the Earth?

Man could get to all corners of our planet. He conquered the earth, flew in the air and descended to the bottom of the oceans. He even managed to get into space and land on the moon. But no one could get to the core of our planet.

Mysteries of the planet

We could not even get close. The center of our planet is located at a distance of 6000 kilometers from its surface, and even the outer part of the nucleus is located 3000 kilometers lower than the person lives. The deepest well that a person has ever managed to do is located on the territory of Russia, but it goes down to some 12.3 kilometers.

All significant events on the planet also happen closer to the surface. Lava, which volcanoes erupt, comes to a liquid state at a depth of several hundred kilometers. Even diamonds, which require heat and pressure, form at a depth of 500 kilometers.

Everything that is below is shrouded in mystery. And it seems incomprehensible. And yet we know surprisingly much about the earth's core. Scientists even have some idea of how its formation took place billions of years ago. And all this without a single physical sample. But how was it revealed?

Earth's mass

A good way is to think about the mass that the Earth has. We can estimate the mass of our planet by observing the effect of its gravity on objects that are on the surface. It turns out that the Earth's mass is 5.9 sextillion tons. This number is 59, followed by 20 zeros. And there are no signs that there is anything massive on its surface.

The density of materials on the Earth's surface is much lower than the density of the planet on average. This means that there is something inside of it with much greater density.

In addition, most of the mass of the Earth should be located towards its center. Therefore, the next step is to find out which heavy metals form its core.

Earth's core composition

Scientists suggest that the earth's core is almost certainly composed of iron. It is believed that its number reaches 80%, although the exact figure is still a topic for discussion.

The main evidence of this is the huge amount of iron in the universe. This is one of the ten most common elements in our galaxy, and it is often found in meteorites. Given this number, on the surface of the Earth iron is much less common than one would expect. Therefore, there is a theory that when the formation of the Earth took place 4.5 billion years ago, most of the iron was contained in the core.

That's why the core makes up the bulk of the mass of our planet, and most of the iron is also in it. Iron is a relatively dense element under natural conditions, and under strong pressure in the center of the Earth it has an even higher density. Therefore, all this mass that does not reach the surface will fall on the iron core. But the question arises. How did it happen that the bulk of iron was concentrated in the core?

Secrets of the formation of the Earth's core

Iron had to somehow literally gravitate towards the center of the Earth. And not immediately you can understand how it happened.

Most of the remaining mass of the Earth consists of rocks called silicates, and molten iron tries to pass through them. Just as water is able to form droplets on a greasy surface, iron collects into small reservoirs, from which it can no longer spread or be expended.

In 2013, scientists at Stanford University in California (USA) found a possible solution. They were interested in what happens when both iron and silicates are subject to severe pressure, as it was once in the center of the Earth. Scientists managed to force the molten iron to pass through the silicate, creating pressure with the help of diamonds. In fact, high pressure changes the interaction of iron and silicates. At higher pressures, a molten network is formed. Thus, it can be assumed that over the course of billions of years, iron was gradually pushed down through the rocks until it reached the core.

Kernel dimensions

Perhaps you are also surprised at how scientists know the size of the core. What makes them think that it is located at a depth of 3000 kilometers from the surface. The answer lies in seismology.

In the case of an earthquake, shock waves diverge all over the planet. Seismologists record these fluctuations. This is the same if we hit one side of the planet with a giant hammer, and on the other hand we listened to the noise created.

A huge amount of data was obtained during the earthquake in Chile, which occurred in 1960. All the seismological stations on Earth were able to record the tremors from this earthquake. Depending on the direction that these vibrations take, they pass through different parts of the Earth, and this affects how they "sound" elsewhere on the planet.

At the very beginning of the history of seismology it became clear that some fluctuations are lost. It was expected that the so-called S-waves will appear from the other side of the planet, but this never happened. The reason for this was simple. S-waves could only be reflected through a solid material and could not do this through a liquid. Thus, they had to pass through something melted in the center of the Earth. Investigating the paths of S-waves, it was found that the solid rock is converted to liquid at a distance of 3000 kilometers below. This allowed us to assume that the earth's core has a liquid structure. But seismologists were waiting for another surprise.

Earth's core structure

In the 1930s, the Danish seismologist Inge Lehmann noticed that another kind of waves, called P-waves, can pass through the Earth's core and be discovered on the other side of the planet. So scientists came to the conclusion that the core is divided into two layers. The inner core, which begins at a depth of about 5000 kilometers from the surface, is in fact a solid. But the outer one is really in a liquid state. This idea was confirmed in 1970, when more sensitive seismographs discovered that P-waves could actually pass through the core, and in some cases deviate from it at an angle. Of course, they could still be heard on the other side of the planet.