Hidden at a depth of 5.000 kilometers, the Earth's core is inaccessible to any direct research. Chinese and American scientists, however, claim that they managed to peer into the very center of our planet where they discovered that there is another core in the center of the core itself.
The researchers, whose study was published in the journal Nature Geoscience, believe that in this deepest part of our planet, the structure of iron crystals differs from that in the outer parts of the core.
Since there is no possibility to reach the heart of the Earth, scientists study its core using the echoes produced by earthquakes. They analyze their changes as they make their way through the different layers of the planet.
Professor Xiadong Song from the University of Illinois told the BBC that "the waves bounce back and forth from one side of the Earth to the other."
These data, he believes, show that the Earth's core - a solid region the size of the Moon - is actually composed of two parts.
Information gathered during the seismic activity suggests that the crystals in the "core of the core" are aligned in an east-west direction, as it were, lying, when viewed downward, high above the North Pole.
The crystals, on the other hand, which are located in the "outer part of the core" are arranged in the north-south direction, i.e. viewed vertically from the same height point.
"The fact that we discovered different structures in different parts of the core tells us about the very long history of the Earth," said Prof. Song.
The solidification of the core, which is located at a depth of 5.000 kilometers, began about a billion years ago. The nucleus continues to grow by 0,5 millimeters per year.
The discovery that it contains differently arranged crystals leads to the conclusion that they were formed under different conditions, and that in a certain period our planet experienced dramatic changes.
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