By Lydia Amazouz Published on June 16, 2024 12:30
Collected at : https://dailygalaxy.com/2024/06/study-slowing-rotation-earths-inner-core/
Recent research has confirmed that the Earth’s inner core, a super-hot and super-dense sphere of iron and nickel, is rotating more slowly than the planet’s surface.
This groundbreaking discovery raises significant questions about planetary mechanics and could impact both the stability of Earth’s magnetic field and the length of our days.
Evidence of Slowing Rotation
Scientists from the University of Southern California (USC) have provided conclusive evidence that the Earth’s inner core began to slow down around 2010. The inner core, located over 4,800 kilometers beneath the Earth’s surface, has always been challenging to study directly. Instead, researchers rely on seismic waves generated by earthquakes to infer its movements
John Vidale, Dean’s Professor of Earth Sciences at USC, and his colleagues analyzed readings from 121 repeating earthquakes recorded between 1991 and 2023 around the South Sandwich Islands in the South Atlantic. These earthquakes, which produce nearly identical seismic waves each time they occur, provided a unique opportunity to observe changes in the inner core’s rotation over time.
In addition to the earthquake data, the team also utilized historical data from Soviet nuclear tests conducted between 1971 and 1974, as well as French and American nuclear tests. Vidale remarked, “When I first saw the seismograms that hinted at this change, I was stumped. But when we found two dozen more observations signaling the same pattern, the result was inescapable.
The inner core had slowed down for the first time in many decades.” This meticulous analysis revealed that the inner core, previously thought to rotate slightly faster than the Earth’s surface, is now lagging behind, marking a significant shift in its rotational dynamics.
Causes and Consequences
The researchers attribute the slowing of the inner core’s rotation to the turbulent movement of the surrounding liquid outer core. This outer core generates the Earth’s magnetic field and is influenced by gravitational forces from dense regions in the overlying rocky mantle. Vidale explained that this interaction between the inner and outer cores is crucial for understanding the dynamics of Earth’s interior.
The slowing rotation could eventually alter the entire planet’s rotation, potentially leading to longer days. Vidale noted that the changes might alter the length of a day by fractions of a second: “It’s very hard to notice, on the order of a thousandth of a second, almost lost in the noise of the churning oceans and atmosphere.”
The implications of this slowdown are profound. The inner core’s rotation is a significant factor in the geodynamo process that generates Earth’s magnetic field. Changes in the inner core’s rotation could potentially impact the strength and stability of the magnetic field, which protects the planet from harmful solar radiation.
A weakened magnetic field could have far-reaching consequences, including increased radiation levels at Earth’s surface and disruptions to satellite and communication systems. Understanding these changes is critical for predicting and mitigating potential impacts on both natural and human-made systems.
Implications for Earth’s Magnetic Field
The inner core’s rotation plays a significant role in the generation and maintenance of Earth’s magnetic field. The interaction between the solid inner core and the fluid outer core creates complex magnetic dynamics that are critical for protecting the planet from solar radiation.
Changes in the inner core’s rotation could potentially impact the strength and stability of the magnetic field, though the exact implications remain uncertain. This area of research is particularly important as Earth’s magnetic field has been weakening over the past few centuries, raising concerns about its future stability.
The potential impact on the Earth’s magnetic field underscores the importance of this discovery. The magnetic field shields Earth from cosmic radiation and charged particles emitted by the sun. A stable magnetic field is essential for maintaining the atmosphere and supporting life on Earth.
Scientists are now tasked with understanding how the slowing rotation of the inner core will influence the geodynamo process and what changes might occur in the magnetic field over the coming decades and centuries.
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