A secret that will take a long time for a person to know first hand what is inside the planet Earth. But even without just going into the depths of this incredible kingdom, we know quite a lot about the Earth’s interior. People walked all over the planet, conquered the earth, flew in the sky and dived into the deepest parts of the ocean. We also sent our representatives to the Moon, but we have never been to the Earth’s interior, writes the BBC.
We haven’t even come close enough to see what secrets the heart of our planet, whose center is at a depth of about 6,000 kilometers, hides. The greatest depth we have ever reached is 12,262 meters, as much as the Kola super-deep well located in the middle of the desolate tundra of the Kola Peninsula in the very north of Europe, which was excavated by Soviet scientists in the period from 1970 to 1989.
All the events we attribute to the Earth’s interior took place at the very surface. The lava coming out of the volcano melts only a few kilometers in depth. Even diamonds whose shaping requires extremely high pressure are found at a depth of approximately 500 kilometers. It will be a long time before man fully discovers what the Earth’s interior hides, but regardless of the fact that we have not yet gone into the depths of this incredible kingdom, we know quite a lot about the Earth’s interior, without any physical evidence.
How we discovered that, explains prof. Simon Redfern is an expert from the University of Cambridge in the UK.
We can calculate the mass of the Earth by observing its gravitational force and the objects that are on its surface. According to these calculations, the mass of the earth is 5.97 x 1024 kilograms, or 59 and another 20 zeros. The density of material on the Earth’s surface is much lower than the average density of the entire Earth, so it can be concluded that there is something much denser inside, said Redfern.
The next question is what heavy metals the Earth is made of. It is known that more than 80% of the Earth’s center is made of iron. The main proof of that is the large amounts of iron in the universe that surrounds us. Iron is one of the ten most common elements we find in our galaxy, and it is also found in meteors. There is also iron on the surface of the Earth, and in fairly large quantities. Therefore, the theory that explains the formation of the Earth states that 4.5 billion years ago, a large amount of iron somehow found its way to the center of the Earth.
It is the center of the Earth, at least so it is assumed, the most difficult and most massive part of our planet. It is known that iron is a relatively dense element under normal conditions, but under the extreme pressure it is subjected to inside the Earth, it breaks down and becomes even denser. This explains the Earth’s mass, and proves that there is a large amount of this metal inside the earth.
How did iron get to the interior of the Earth?
Iron literally gravitated to the Earth’s interior, but the way it got there for years intrigued scientists, and then the answer arrived.
The rest of the Earth’s interior consists of rocks made of silicate through which molten iron finds its way to the womb. A similar thing happens with water when it flows through a greasy surface and, squeezing in droplets, travels through the ground. Iron travels in small, let’s call them reservoirs, avoiding spilling into large widespread streams.
The 2013 iron flow solution was offered by Wendy Mao of Stanford University in California. In her paper, she posed the question of what happens to iron when it encounters silicates and what happens when they both come under extreme pressure to which they are exposed deep below the Earth’s surface.
The pressure actually changes the structure and properties of iron, which then behaves differently when in contact with silicates. In the conditions that are in the depths of the Earth, at high pressure, its structure melts, Mao explained. In his work, he proposes a solution according to which iron gradually passes through the rocks of the Earth, and the process of traveling to the center takes millions of years.
How do we know the size of the core?
After learning the composition of the Earth’s core, the next question that arises is how do we know its size? How do we know it starts at a depth of 300 kilometers? The answer was given by seismography. It is true that earthquakes can be destructive, but we can learn a lot from them. At the time of the earthquake, man-made devices receive signals in the form of radio waves propagating across the planet. Seismologists, measuring the vibrations and vibrations of the ground, come to various conclusions – as if we were hitting a large hammer on one side of the Earth, and then listening to the produced sound at the other end.
The 1960 earthquake in Chile was very helpful in collecting data on the Earth’s interior, Redfern explains, adding that due to the path that these vibrations propagate, they pass through different parts of the Earth, which affects the sound we can eventually hear. In earlier seismological history, the disappearance of some vibrations was recorded, the so-called S-waves, which were expected to appear on the other side of the Earth. But they disappeared without a trace. The reason for this is simple. C-waves can echo through solid, solid material, but not through liquids.
Therefore, S-waves on their way to spread through the Earth’s interior had to encounter something liquid. Seismologists skillfully recorded each such missing wave and finally calculated that at a depth of about 300 kilometers, rocks and stones melt and turn from a solid to a liquid state. This is exactly what suggests that the center of the Earth is made of thick but liquid matter. But there is something else.
Danish seismographer Inge Lehman discovered the existence of another type of wave in the 1930s – P-waves that travel unexpectedly through the Earth’s center, its core, and their influence is visible, ie felt at the other end of the planet. Lehman provided a solution for such wave propagation. The earth’s core is divided into two layers, Lehmann said. According to her discovery, the inner layer of the Earth’s core begins at a depth of about 5,000 kilometers and is actually in a solid state, while the upper layer of the core consists of metals and rocks, converted into liquids.
This proposed answer to the question was confirmed in 1970. Seismologists have discovered through detailed analysis and more advanced technology that P-waves actually travel through the center of the Earth’s core, and in some cases are reduced, brushed, reduced due to the encounter with the liquid that makes up the upper part of the core. It has been proven that in the end they end up in another part of the planet.
Nuclear weapons as a learning tool
It is not only earthquakes that teach us a lot. Seismologists have been helped in many discoveries by the development of nuclear weapons. The detonations produced by a nuclear explosion cause waves to form on the surface of the ground, as well as in the ground itself, which is why many nations use the services of seismologists to detect military activities on the other side of the world.
During the Cold War, such a practice was extremely important. Thanks to countries competing with each other over nuclear weapons, additional details and insights about the interior of our planet have been revealed. Thanks to their calculations, today we can draw and publish the Earth’s structure without fear of mistakes.
There is a molten outer layer of the core that begins about halfway from the Earth’s center, inside which is a solid core about 1,220 kilometers in diameter. But that’s not all.
The issue of core temperature is one of the most difficult. Until recently, there was no answer, but that problem was solved by Lidunka Vočadlo from the University of London. It is not possible to place the thermometer so deep, but in the laboratory we can create conditions that are effective in the interior of the Earth. In 2013, French researchers gave the best predictions so far. Testing pure iron that is subjected to high pressure and slightly higher than half of the assumed temperature that heats the Earth’s interior, they came up with interesting results.
They concluded that the melting point of iron in the Earth’s interior is about 6,230 degrees Celsius, but due to the presence of other metals, it is still slightly lower, amounting to about 6,000 degrees, which corresponds to the temperature on the surface of the Sun.
The earth has managed to maintain its temperature since the beginning of its formation, and it gained heat thanks to the friction of the dense substances of which it is made, as well as from the decay of radioactive elements. But every billion years, the Earth’s core cools by about 100 degrees Celsius.
Occurrence of P-waves
Earth’s temperature also affects the speed at which vibrations caused by earthquakes travel. P-waves travel unexpectedly slowly through the interior of the Earth, slower than if the Earth’s core were composed exclusively of iron. This indicates the existence of some more metals in the earth’s core. It could be nickel, but scientists note that the waves through the combination of iron and nickel would not travel at the speed at which they travel now. Vochadlo and colleagues are now considering the possibility of the existence of other elements such as sulfur and silicon. So far, no one has come up with a satisfactory answer to the question of the composition of the inner part of the Earth’s core.
Vochadlo therefore tries to figure out what is actually there by computer simulation of the matter of the inner part of the nucleus. He says that the secret lies in the fact that the inner part of the core corresponds to the melting temperature. As a result, the exact properties of matter could be somewhat different from what it would be if they were solid. This would explain the appearance of a slower passage of waves through the Earth’s interior.
Although we know a lot about the interior of our planet, there are a number of puzzles that are still waiting to be solved. But even without digging deep holes, scientists have successfully discovered what lies thousands of miles below our feet.
Although we do not think about them, the events that take place in the center of the Earth are of great importance to our planet. The earth has a powerful magnetic field thanks to its core. The constant movement of molten iron creates an electric charge that serves as a kind of generator to create a magnetic field that reaches deep into space.
The magnetic field created by the Earth’s core protects us from harmful solar radiation. If the nucleus were not as it is now, there would be no magnetic field, and only then would we run into real problems, much bigger than our ignorance.