The inner core of planet Earth would have slowed down

According to a new study, the inner core of planet Earth would have slowed down to the same rotational speed as the outer layers, or even a little less. From the surface we would see it as if it had stopped, or in the opposite direction. This is explained by researchers from the Institute of Geosciences (CSIC-UCM), who clarify that it is unlikely that these small changes will have appreciable effects.

recently published a to study in which it is said that the Earth’s core has ruptured and that this event has an influence on different aspects of the planet, such as the magnetic field or the climate.

Following this publication, some voices emerged suggesting exaggerated and catastrophic consequences. It is important to analyze this news with a critical eye and, without minimizing the great impact of scientific discoveries on the functioning of our planet (even with so many mysteries), not to fall into simplicity or drama.

Earth’s internal structure

To understand this novelty, we must first know the internal structure of our planet. The Earth is made up of different layers. At the center is the inner core, a solid sphere of iron and nickel with a radius of 1,220 km. It is surrounded by a layer 2,260 km thick of similar composition, but in a molten state, the outer core.

The convection movements in this fluid layer, together with Earth’s rotation, generate the magnetic field that protects our planet from particles arriving from the Sun and space. Around the core we find the mantle, about 2,900 km thick, and above this, the Earth’s crust in which we live, which is only 10 to 50 km thick.

The first thing to clarify is that the kernel has not stopped. The Earth with all its layers is rotating in such a way that it takes approximately 24 hours to complete one revolution.

Until now, the inner core was thought to be rotating slightly faster than the mantle and crust (this is called superrotation), so it was advancing by about a tenth of a degree each year.

According to this new study, the core would have slowed down to the same rotational speed as the outer layers or even a little less. These relative speed differences are very small.

The example of the car on the road explains this phenomenon from the inner core of planet Earth.

Consider, for example, that we are going on the highway at 120 km/h and another car passes us at 121 km/h. Through the window we will see that he is gradually overtaking us. If the other vehicle now brakes and accelerates to 120 km/h, we will see it “immobile” next to our car, although it continues to move, just like us.

In the same way, the core would have slowed down and, now, rotating at the same speed as the mantle and crust, from the Earth’s surface we would see it standing still.

To reach the conclusion that the core is now rotating more slowly, the researchers selected earthquakes originating in the South Sandwich Islands, in the southern part of the Atlantic Ocean, and studied the signal recorded at an observatory in Alaska, almost on the other side of the planet. .

In this way, they were able to analyze the time it took for the waves to cross the Earth’s core to arrive, always following the same paths. They observed that the waves took different times to pass through the core at different times.

Properties of Earth’s core zones

Different areas of the core can have different properties, meaning waves take longer to pass through some areas than others, so they concluded that if the travel time of waves has changed over the years, it’s because the inner core was getting ahead of itself. to the cortex.

That is, if for waves emitted and recorded at the same points on the surface we obtained different results depending on time, it means that the waves are passing through different areas of the core, that is, it is rotating at different speeds than the surface of the core.Earth .

However, since 2009 the waves have always taken the same amount of time to pass through the core. This means that the core is now at rest relative to the surface (it rotates at the same speed). The same results were obtained when the study was extended to earthquakes generated in other parts of the planet, corroborating the previous conclusions.

This slight change in core rotation isn’t the first time it’s happened. The data show another similar event in the 1970s. This suggests that the phenomenon repeats itself with a periodicity of about seven decades.

Association with geophysical phenomena

Interestingly, this same frequency also appears in other geophysical observables such as the geomagnetic field, day length or weather, which suggests that they may be related.

It is currently thought that this phenomenon of periodic variation in the rotation of the core is due, on the one hand, to the electromagnetic interaction between the inner and outer core that tends to accelerate the inner core and, on the other hand, to the gravitational coupling with the mantle, which forces you to return to the rhythm.

In short, does the study say that the core stopped in 2009 and will start spinning in the opposite direction? No, it just changed its speed relative to the crust.

Throughout history, the magnetic field has already reversed several times. Does this deceleration of the core suggest an imminent new reversal of the poles or could the magnetic field disappear? No, the core continues to rotate and the magnetic field continues to be generated.

Planet Earth’s inner core phenomenon will have implications for climate

The article proposes that some relationship may exist, but that the origin of multidecadal variations in climate is still not fully understood. Furthermore, it does not seem likely that such small changes in core rotation could have really appreciable effects.

As we can see, Earth’s dynamics is a system of great complexity and there are an infinity of interconnected factors that determine the characteristics and evolution of our planet.

Earth’s long history compared to our study makes understanding its evolution a major challenge. Discoveries like this are a sample of science’s efforts to understand more and more how the planet we live on works.

Alberto Molina Cardin, Borque Marina Bridge Y Pablo Rivera Perez They are researchers from the Institute of Geosciences (IGEO), a joint center of the Higher Council for Scientific Research (CSIC) and the Complutense University of Madrid (UCM)


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