Join CNN’s Wonder Theory science newsletter for a journey through the cosmos with updates on groundbreaking discoveries and scientific progress. Recently, scientists made a significant breakthrough in unveiling the mysteries of Earth’s inner core, shedding light on its concealed transformations. This innermost layer of our planet, a solid metal sphere enveloped by a liquid metal outer core, has long been a subject of intrigue and speculation among planetary researchers.
In a groundbreaking study published in the journal Nature Geoscience, experts shared their findings on changes observed in the shape of the inner core over the past two decades. By analyzing seismic waves from earthquakes that managed to penetrate Earth’s core, researchers detected signs of deformation in this deep-seated region. The study also settled a longstanding debate regarding the inner core’s rotation, revealing a surprising shift in its spin dynamics.
Notably, the solid inner core was found to have once rotated faster than the Earth itself, but since around 2010, its spin has gradually slowed and even reversed direction relative to the planet’s rotation. This new insight, based on earthquake data collected from 1991 to 2023, offers a fresh perspective on the inner workings of our planet and its core dynamics.
Dr. John Vidale, a leading expert on Earth sciences at the University of Southern California, emphasized the significance of these findings in understanding the forces at play deep within Earth’s core, which influence critical phenomena like our planet’s magnetosphere. This invisible shield of magnetic energy shields Earth from solar activity and radiation, highlighting the importance of studying these inner core transformations.
Exploring the depths of Earth’s inner core is akin to delving into a realm of science fiction, given its remote and enigmatic nature. This solid core of iron and nickel, nearly the size of the moon, exists at unimaginable temperatures and pressures far beyond what we experience on the surface. While direct observation of the inner core remains elusive, scientists leverage seismic wave data to unravel its mysteries and unlock its secrets.
By delving into the inner core’s evolution on a geological timescale, researchers aim to deepen our comprehension of Earth’s intricate dynamics and uncover the hidden forces shaping our planet’s core. This ongoing exploration promises to fuel further debates and push the boundaries of scientific understanding.
The initial seismic waves from an earthquake cause the ground to move in the direction of the wave, while the shear waves (S waves) move the ground perpendicular to the wave’s direction at a slower pace than the primary waves (P waves). A recent study suggests that amplitude variations in a particular type of P wave that penetrates the core, known as PKIKP waves, indicate deformations in the shallowest level of the inner core. This research proposes that at the boundary between the solid inner core and the liquid outer core, the surface may exhibit more malleability compared to deeper levels.
The scientists examined 168 paired waves from earthquakes near the South Sandwich Islands in the South Atlantic Ocean, observing changes in the core’s shape by tracking its rotation speed and direction. By modeling the core’s position based on its rotation speed and comparing PKIKP waves reaching the core as it rotates, the researchers could attribute amplitude changes in the waves to shape alterations in the core. The exact nature of these inner core deformations remains uncertain, with possibilities ranging from undulating topography to gradual movements akin to landslides caused by the outer core’s pressure on the inner core.
While only one location in the inner core showed signs of deformation between 2004 and 2008, the researchers suspect that there may be more undetected instances. As the solid inner core spins and interacts with the churning outer core, generating magnetic energy that envelops the Earth in a protective magnetosphere, the core’s gradual cooling and solidification process continues. Over billions of years, the inner core will likely absorb liquid metal from the outer core until the entire core becomes a solid metal sphere, ultimately extinguishing the planet’s magnetic field.
This transformation is projected to occur billions of years from now, long before which the sun is anticipated to expand into a red giant and engulf the inner planets of the solar system. Scientists are encouraged to investigate the inner workings of Earth to unravel the mysteries of its spinning, churning, and shape-shifting core. The growth of the inner core is crucial for Earth’s magnetic field, which shields the planet from harmful solar radiation, highlighting the significance of understanding these dynamic processes for the future well-being of life on Earth.
Although a direct connection between life on Earth’s surface and the ICB (inner-outer core boundary) remains distant, the events occurring at the ICB still hold significant implications for Earth’s long-term evolution. Mindy Weisberger, a science writer and media producer, has contributed to renowned publications such as Live Science, Scientific American, and How It Works magazine. To stay updated with more CNN news and newsletters, sign up for an account at CNN.com.
