We are all aware, to a greater or lesser extent, of what our planet Earth is made of. If we go back to science classes in school, we recall the concepts of the Earth’s core, inner core, mantle, or crust. However, recent discoveries suggest that there is an even more internal inner core. Its composition is made up of iron crystals arranged differently from the rest of the inner core, indicating that not all the materials that make up the Earth’s core are the same. How could this discovery have been made? Scientists have based their research on the use of seismic waves caused by earthquakes.
After studying how the waves traveled through the planet, they discovered that their behavior was different. This led to the creation of the term anisotropy, which reflects that the inner core is not uniform, as it was once thought. Until now, it was believed that the outer core was made up of molten iron and nickel, which was responsible for creating the Earth’s magnetic field. However, the possibility is now being considered that the core contains both solid and liquid metals at the same time, and that the functioning of the heart of our planet is still to be discovered.
Planet Earth
If we are presented with a drawing of the Earth and its parts, like in school, most of us would likely be able to point out each layer with a relatively small margin of error. However, if we are asked about its composition or function, we would be entering another level. Therefore, let’s review this information before delving into the discovery itself.
- Earth’s crust: It is the thinnest of the Earth’s layers and is its surface. This is where we currently have our feet.
- Earth’s mantle: Just below the crust, it is one of the thickest layers, composed of rock. It is not a solid layer, but rather has a thickness that is responsible for earthquakes, volcanoes, and the movement of continents.
- Outer core. We are already delving into the deeper layers. It is composed of molten iron and nickel, and is responsible, with its movement, for the Earth’s magnetic field. Additionally, it is what we must thank for protection against solar radiation.
- Inner core. The innermost point, a solid ball of iron and nickel, which exists due to the extreme pressure.
New discovery
So far, that was all. The four layers of the Earth and their functions. However, a surprise has emerged in recent research. The existence of a fifth layer, the ‘inner-inner core,’ has been detected. Researchers believe it is made of iron crystals that are arranged differently from the rest of the core. This finding not only adds a layer to the Earth, but also reveals the possibility that the Earth went through two cooling events billions of years ago. It is also a logical explanation for why some of the experiments related to blue marble did not match, and it also opens a door to understanding the formation of the Earth’s magnetic field.
How was this discovery achieved?
The arrival of humans at the Earth’s core is impossible. However, scientists rely on other methods to study it. In this case, they have used the seismic waves generated by earthquakes. In this way, the behavior of the waves traveling through the planet has been analyzed, determining that it varied depending on the materials it encountered along the way. This has been known as anisotropy, meaning the difference in wave behavior, which demonstrates that the inner core is not homogeneous.
What now?
This new finding challenges what scientists and the world thought they knew about the Earth’s layers, especially regarding its core. Further research will be necessary to reach more definitive conclusions, as data from some parts of the world is still lacking. Nevertheless, such events remind us of the magnificence of our planet and its ability to surprise us when we think we already know everything about it.