Thousands of kilometers underground, a scientific phenomenon takes place that no one can explain.
But the inner core of our planet, a compact mass of iron and nickel, is growing faster on one side than on the other.
A study conducted by seismologists at the University of California, Berkeley, USA and published in the journal Nature Geoscience found that the core area, which is in an area below the Banda Sea in Indonesia, is larger than the part which is below the other extreme Brazil.
Using computer simulations, experts have created a kind of map that shows the growth of the Earth’s core over the past 1 billion years.
And they came to the conclusion that it behaved in an “unbalanced pattern”, with new “iron crystals” forming more quickly on its Asian side.
“The west side looks different from the east side to the center, not just at the top of the inner core as some have suggested. The only way to explain this is that one side grows faster than the other,” said Daniel Frost, one of the scientists who participated in the research, in a statement.
According to experts, this phenomenon has an impact on the Earth’s magnetic field (which protects us from the dangerous particles of the sun).
Because the magnetic field is created by convection in the outer core, driven by the heat dissipation of the inner core.
The interior of the earth consists of layers that are similar to those of an onion. The last of them (the deepest) is the massive inner core of iron and nickel, which is 1,200 km in radius, about three-quarters the size of the moon.
It is surrounded by a liquid outer core made of cast iron and nickel around 2,400 km thick. The outer core is in turn surrounded by a 2,900 km thick hot rock mantle and covered on the surface by a thin, cold rock crust.
By studying seismic waves, experts analyze how these layers behave, but have been finding for years that the waves do not spread in the same direction as they propagate between the poles and in the equatorial zone.
This assumption was the basis for understanding that there might be some difference in the Earth’s core that is responsible for this phenomenon.
“The movement of liquid iron in the outer core removes heat from the inner core and freezes it,” Frost said in Live Science magazine.
“That means that the outer core received more heat from the east side [sob a Indonésia] than from the west [sob o Brasil]”he added.
The best way to imagine what is going on thousands of kilometers down, the scientist said, is to imagine an incision in the tree trunk formed by annual rings extending from a central point.
The center of the rings would in this case be shifted from the center of the tree so that the circles are further apart on the east side of the tree and closer together on the west side.
However, this faster growth under the Indonesian Sea did not unbalance the core, the scientists explain.
Gravity distributes the new growth evenly, keeping the inner core spherical and expanding its radius by an average of one millimeter per year.
the core age
Computer simulations also made it possible for seismologists to determine a more precise date for the formation of the Earth’s core.
And the core is known to have formed when the earth was already organized, apparently from the concentration of metals such as iron and nickel.
“We have set very flexible limits for the age of the inner core between 500 and 1.5 billion years, which could help in the debate about how the magnetic field was created before the solid inner core existed,” said Barbara Romanowicz, another Researchers who participated in the study.
“We know the magnetic field existed 3 billion years ago, so other processes must have driven convection in the outer core back then,” he added.
According to the research, the younger age of the inner core could mean that the heat that boiled the liquid core at the beginning of Earth’s history came from light elements separating from the iron, rather than from the crystallization of that metal.