Unveiling Earth’s Mysteries: How Scientists Discover the Shifting Shape of Our Inner Core

Earth’s Inner Core: Recent Discoveries Unveiled

Scientists have recently made an intriguing discovery about Earth’s inner core. They confirmed that in addition to reversing its spin, the shape of this hidden layer is changing.

Earth’s inner core is a solid ball made of iron and nickel, surrounded by a liquid outer core. For years, scientists believed the inner core deformed as it rotated, but now, researchers have found clear evidence of this deformation over the past two decades. They identified changes by studying seismic waves from powerful earthquakes that penetrated the core.

Using data from earthquakes between 1991 and 2023, a research team has uncovered that the inner core, which once rotated faster than Earth, has now started to spin backward since around 2010. This shift raises questions about the dynamics within our planet.

Dr. John Vidale, the study’s lead author, explained that they compared seismic signals to discern patterns of deformation in the inner core. He noted that changes in its shape might provide clues to the forces generating Earth’s magnetosphere, the protective magnetic field surrounding our planet.

A colleague, Dr. Yoshi Miyazaki, highlighted the significance of observing these core changes annually, enhancing our understanding of deep Earth dynamics. He added that this research brings a fresh perspective by exploring shape changes in addition to rotational changes.

The inner core remains a mystery. It is about 70% the size of the moon, with a diameter of approximately 1,500 miles (2,400 kilometers). With temperatures soaring up to 9,800 degrees Fahrenheit (5,400 degrees Celsius) and crushing pressures, exploring it directly isn’t possible. Instead, scientists study seismic waves that provide insights into its properties.

Seismic waves are generated during earthquakes, with two main types: primary waves (P waves) and shear waves (S waves). The new study focused on P waves that travel through the inner core, revealing changes at its outer layer, where it meets the liquid outer core. This suggests the surface of the inner core might be more flexible than once thought.

As the solid inner core turns, it interacts with the liquid outer core, creating magnetic fields that envelop the Earth. Over time, though, the outer core is shrinking as the inner core continues to pull molten metal from it. This ongoing process gradually leads to a solid inner core, which could take billions of years to fully solidify.

Dr. Vidale warned that once the inner core solidifies completely, Earth could lose its magnetic field. However, this event is eons away. By then, our sun is expected to expand and potentially consume the inner planets of our solar system.

This research emphasizes the inner core’s role in generating Earth’s magnetic field, essential for protecting life from harmful solar radiation. Although the direct impact on life remains unclear, the study of the inner core adds vital knowledge about Earth’s long-term evolution.

Mindy Weisberger is a science writer whose work has appeared in various renowned publications.