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The Earth's core, more than 5.100 km deep, is finally being unraveled by physicists. Learn more about the discoveries that are revealing hidden secrets from the heart of our planet.
5.100 km deep, at the center of our planet, is the Earth's core, a solid sphere composed mainly of iron and nickel.
This unknown part of the planet plays a vital role in maintaining surface conditions, including creating the magnetic field that protects us from solar radiation. Without it, life on Earth might never have existed.
Despite the importance of the inner core, many mysteries about its formation and age still remain unanswered. Now, the Physics mineral is helping us get closer to solving this puzzle.
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The role of the Earth's core in the magnetic field
The inner core, essential for the formation of the Earth's magnetic field, which acts as a protective shield against solar radiation, may have been fundamental in creating the conditions that allowed the emergence and prosperity of life. billion of years.
What we do know is that the inner core was not always solid. Initially, it was liquid, but as the Earth cooled over billions of years, the core began to solidify, expanding outward.
This transformation released elements such as oxygen and carbon, which cannot remain in a hot solid state.
These elements create a floating liquid at the bottom of the outer core. The liquid then mixes with the liquid outer core, generating electric currents and, through the action of the dynamo, creates the magnetic field that protects the planet.
This magnetic field not only blocks harmful solar radiation from reaching the Earth's surface, but is also responsible for phenomena such as the aurora borealis — the northern lights that shine in the sky thanks to the workings of this invisible dynamo at the heart of our planet.
The process of core crystallization
Understanding how the magnetic field has evolved throughout Earth’s history depends on simulating the thermal state of the core and mantle. These models help geophysicists understand how heat is distributed and transferred within Earth.
The current consensus is that the solid inner core emerged when the liquid around it cooled to its melting point and began to freeze. However, this freezing process is not as simple as it seems.
Scientists have explored the concept of “supercooling,” a phenomenon that occurs when a liquid is cooled below its freezing point without becoming a solid. This happens with water in the atmosphere, which can reach temperatures of -30°C before turning into hail, and it also happens with iron in the Earth's core.
Theoretical models suggest that about 1.000 Kelvin of supercooling is required to freeze pure iron in the core. However, the core's cooling rate, being approximately 100 to 200 Kelvin per billion years, makes this scenario highly unlikely.
If the core had been supercooled to 1.000 Kelvin, the inner core should be much larger than it is today. On the other hand, if that temperature was never reached, the inner core should not even exist.
Recent advances and physical opportunities
To resolve this paradox, mineral physicists are conducting experiments with pure iron and mixtures of other elements to determine the level of supercooling required to initiate the formation of the inner core. Although the studies are still ongoing, significant progress is being made.
One of the most recent discoveries suggests that the presence of carbon and unusual crystal structures may reduce the need for excessive supercooling.
This indicates that the chemical composition of the core may play a more important role in the solidification process than previously thought.
If the inner core could form at less than 400 Kelvin of supercooling, this could explain why the inner core exists in the form we see today.
The Impact of Not Understanding the Inner Core
Understanding the formation of the inner core has significant implications. Previous estimates suggest that the inner core is between 500 and 1.000 million years old, but these assumptions did not take into account the phenomenon of supercooling.
If we take into account even a modest supercooling of 100 Kelvin, this could mean that the inner core is much younger than previously believed, possibly several hundred million years younger.
These questions are not only relevant to understanding the Earth as a whole, but may also have implications for scientists studying the relationship between the magnetic field and mass extinction events in the paleomagnetic record.
Until we fully understand the history of Earth's magnetic field, it will be difficult to accurately assess its role in creating conditions favorable to life on the planet.
The study of the Earth's inner core is still in its early stages, and much remains to be discovered.
Through advances in mineral physics and geophysical models, we are beginning to unravel how the inner core formed and how it shaped the magnetic field that protects our planet to this day.
While many questions still need answers, each new discovery brings us closer to understanding the mysteries of Earth's heart and the vital role the inner core plays in the habitability of our world.
