Scientists in China recently made a discovery at the heart of our planet: Every 8.5 years, the Earth's inner core moves around its axis of rotation. This shift is likely caused by a small discrepancy between the inner core and the Earth's mantle — the layer beneath the surface , according to the researchers' new study.
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About 2,896 km below the surface, the Earth's core is divided into a wavy, liquid outer shell and a mostly solid inner layer. This region is partly responsible for some of planet , from the length of each day to the Earth's magnetic field, which helps protect humanity from harmful rays emitted by the sun.
This recent tilt inside the core could potentially lead to a change in the shape and motion of the liquid core, resulting in a possible shift in Earth's magnetic field, according to a study published Dec. 8 in the journalNature Communications.
To better understand the inner workings of this core, geophysical researchers led by Hao Ding of Wuhan University analyzed the movement of Earth’s axis of rotation relative to its crust, known as polar rotation, in 2019. They detected a small deviation in the polar motion that occurs about every 8.5 years, indicating the possible existence of an “ inner core wobble ,” similar to that of a spinning gyroscope.
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For their latest study, Ding and his co-authors confirmed this cycle by measuring small shifts in the length of the day around the world — which is controlled by the periodic motion of Earth's rotational axis — and comparing them to variations in polar motion they had previously identified. data suggest that this anomaly is likely due to a 0.17-degree tilt between Earth's inner core and mantle, contrary to the traditional theory of Earth's rotation that "assumes that the rotation axes of the inner core and mantle coincide," Ding told Live Science in an email.
This tilt may indicate that the northwestern hemisphere of the inner core may be slightly denser than the rest of the sector, and that there is also a difference in density between the Earth's inner and outer cores, according to the research.
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Moving forward, this discovery may help researchers understand the dynamics between the Earth's inner core and processes that affect humanity, from seismic vibrations to changes in the magnetic field.
Source: livescience
