The shape of Earth's core is changing

Scientists have uncovered new information about the Earth's core: it may not be completely solid. Instead, it may be more malleable than expected, and has changed shape in recent years. These findings could lead to a better understanding of the inner workings of our planet and how life here will evolve over time.

'Almost science fiction'

The Earth is made up of different layers. The outermost layer is the crust, which is where we stand. The next layer is the mantle, which makes up most of Earth's volume and is composed of dense, semi-solid rock. Then there is the outer core, made of liquid metal, and the inner core, a solid ball of metal. At least, that is what we thought.

New research published in the journal Nature Geoscience found that the core's shape has shifted in the past 20 years. Scientists say the shape change is happening where the solid inner core meets the molten outer core. "The molten outer core is widely known to be turbulent, but its turbulence had not been observed to disrupt its neighbor the inner core on a human timescale," John Vidale, a professor and earth scientist at the University of Southern California, as well as the principal investigator of the study, said in a statement. "What we're observing in this study for the first time is likely the outer core disturbing the inner core."

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These findings come after researchers studied seismic waveform data from 121 repeating earthquakes between 1991 and 2024 across 42 different locations near the South Sandwich Islands, north of Antarctica. "As I was analyzing multiple decades' worth of seismograms, one dataset of seismic waves curiously stood out from the rest," Vidale said. "Later on, I'd realize I was staring at evidence the inner core is not solid." Further, the data showed that the inner core had been moving around and not behaving like a solid ball of metal. Visualizing what is happening at the inner core is "almost science fiction," Vidale said to CNN, because it is "so different from our day-to-day lives, with different timescales, different materials and incredible forces."

'A new perspective'

Earth's core has been a growing topic of interest. It is responsible for the planet's magnetic field, which protects life from the sun's radiation. Despite its importance, there is still much that scientists do not know about the center of the Earth. A 2024 study, for example, found that the rotation of Earth's core had slowed down. But this new study "introduces a new perspective — non-rotational changes — adding another dimension to the discussion," Dr. Yoshi Miyazaki, an associate professor in the Department of Earth and Planetary Sciences at Rutgers University, said to CNN. The structural and rotational changes of the core may have even "minutely altered the length of a day," USC Today said.

The new research presents a unique opportunity to witness changes to Earth on a smaller timescale. "Earth evolves on a geological timescale, so observing changes on an annual timescale is always intriguing, as it enhances our understanding of inner core dynamics," said Miyazaki.