Researchers are still discovering more about the center of the Earth. A team at the Australian National University (ANU) has found evidence of a new layer of the planet sitting within the inner core. This “innermost core” is an iron-nickel alloy ball which, as professor Hrvoje Tkalčić explained, is a “fossilized record” of Earth’s ancient history. Until now, science has only recognized four layers (crust, mantle, outer core and inner core).
Scientists found the ‘hidden’ core by studying seismic waves that bounce around the Earth’s diameter up to five times – previous studies only looked at one bounce. Seismic waves probe the areas near the center at angles that suggest a different crystal structure within the innermost layer. Effectively, the alloy skews the travel times for the waves as they pass through.
The findings open up new ways to investigate the interior, according to lead author Thanh-Son Phạm. The ANU also believes that the inner core heralds a major event in Earth’s past that had a “significant” impact on the heart of the planet. As the researchers explained The Washington Post, it also helps explain the formation of Earth’s magnetic field. The field plays a major role in supporting life because it protects the Earth from harmful radiation and prevents water from drifting into space.
Those insights may help in studies of other worlds. Mars is thought to be a barren planet because it lost its magnetic field about four billion years ago, leaving no protection against the solar wind and dust storms that carry the atmosphere and oceans. Exoplanet hunters, on the other hand, can use the knowledge to search for habitable worlds. The presence of an Earth-like core structure is not guaranteed to indicate survivability, but may play a role in narrowing down candidate planets.
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