New secret of the earth's center: Is there an "inner core" hidden deep inside the earth?

As you may know, the earth is divided into four layers, namely the crust, mantle, outer core and inner core. However, not long ago, an Australian scientific team discovered that there are changes in the iron structure of the earth's inner core, and there is a "boundary line" 650 kilometers away from the core. This shows that the earth's inner core is a double-layer structure, and there is an "inner core" in the currently known inner core. Once this research result is recognized, it means that there is a small structure buried deep inside the core. The "inner core" may be the real core of the earth. Of course, there may be structures in this core that we have not yet discovered. And this means that human textbooks about the earth may be rewritten...

Prior to this, scientists used data from geological activities such as earthquakes and volcanic eruptions to study the deepest part of the Earth and determined that there is an innermost core structure inside the Earth, but the relevant data has always been vague. Unlike traditional methods, this time the Australian scientific team used a "search algorithm". They tracked and matched thousands of "Earth core area" models through decades of data collected by the International Seismological Center on the time it takes for seismic waves to propagate through the Earth, and found through their own algorithms that although the depth of the Earth's core has not changed, that is, the radius of the Earth has not changed, there has indeed been a change in the direction of the waves inside the Earth, with an angle of 54 degrees, and the direction of the fast waves is parallel to the axis. This tiny fluctuation indicates that there is a hidden structure inside. The tiny changes in the iron structure indicate that a dramatic unknown event occurred in the first few years of the Earth's evolution - about 4.5 billion years ago. Although the specific details of the event remain a mystery, it adds a piece to the puzzle for scientists to understand the Earth's inner core.

According to the latest research by scientists, the structure of the earth should be 5 layers, not 4 layers as previously believed (Image source: Visual China)

According to the team, as seismic waves pass through the core, their changes reveal subtle differences in the iron structure. Scientists point out that due to the limitations of the distribution of earthquakes and receiving locations around the world, especially at the Earth's poles, there are many interference factors and gaps, so the relevant data is not perfect, which reduces the certainty of the conclusions. However, they are quite confident in this major discovery because the conclusions are consistent with other studies on the anisotropy of the Earth's innermost core (anisotropy is the way differences in material composition change the properties of seismic waves). Next, they will explore the Earth's related wave fields, including superimposed data from a series of wave field sources. In this way, it will be possible to improve the understanding of the Earth's inner core without being constrained by the deep Earth structure in the case of limited distribution of sources and receivers, and to depict a more detailed picture of the movement of the Earth's interior and enhance the understanding of the Earth's evolution.

The Kola borehole was drilled to a depth of 12,262 meters underground

Physicists believe that the formation and stability of the Earth's magnetic field are related to the Earth's inner core. They calculated the possible structure of the Earth's core by studying and analyzing the shock waves generated by earthquakes. The Earth's core is a solid inner core, equivalent to 2/3 of the volume of the moon, and its main component is iron. At the high temperature of the Earth's core, the temperature of iron is similar to that of the surface of the sun, but the crushing pressure caused by gravity prevents iron from becoming liquid. The outer core is located below the mantle and above the solid inner core. It is composed of liquid iron and nickel and has a thickness of about 2,200 kilometers. The temperature range of the outer core increases from about 440or on the outside to 600or near the inner core. The difference in temperature, pressure and composition of the outer core causes convection of molten metal. Since the lower temperature material sinks and the higher temperature material rises, there is not enough pressure to make it solid, so it appears in liquid state. The inner core becomes solid as the liquid iron continues to cool, with a maximum depth of 6,370 kilometers. It is composed of a solid iron-nickel alloy that is very rigid and crystallized under extremely high pressure. The pressure at the center of the Earth's core can reach 3.5 million atmospheres and the temperature can reach 6,000 degrees Celsius. Under such high temperature and high pressure conditions, the characteristic of the inner core material is that under the long-term action of high temperature and high pressure, it is plastic like resin and wax, but when faced with short-term forces, it is harder than steel.

This time, scientists discovered that the Earth's inner core is a "nesting doll" structure. As the innermost core, the "inner core" is a different type of unknown structure with a diameter approximately half the diameter of the entire inner core, 650 kilometers from the Earth's core, solid iron, with a temperature of more than 5000 degrees Celsius, and has significant anisotropy relative to other core layers. The iron crystals in the outer core point north-south, while in the "inner core" the iron crystals point east-west, which means that its material may have different types of crystal types.

So far, we have not had a "substantial" study of the internal state of the Earth, and have only roughly divided it according to the activities of the Earth. The discovery of the Earth's "inner core" may not bring much change to our daily lives, but it is a big step for scientists to better understand the formation of the Earth and other similar planets, and can explain some information about how the Earth's inner core evolved. For example, in the history of the Earth, the deformation range of the inner core may have undergone great changes, which may hide key information about the evolution of the Earth.

How scientists learned about the Earth's interior

Some people may be puzzled by the fact that scientists can understand the internal structure of the earth so clearly: if you can't see it, how can what they say be true? Are they just guessing? If you have done an ultrasound or CT scan, you will know this very well. Waves will change in direction and speed in materials of different densities. By measuring this change, the instrument can draw the internal situation of the body and find the lumps inside. The same is true for the interior of the earth, but if you do a CT scan of it, you will need more spectacular seismic waves. Fortunately, there are seismometers all over the world that faithfully record the detailed data of every earthquake. By analyzing and studying these data and building different computer models, scientists can get a glimpse of the different structures inside the earth and what materials it is made of.