"Almost Science Fiction": Scientists Say Earth's Mysterious Inner Core Is Changing Shape

New research has suggested that the Earth's inner core may have undergone a significant transformation in its shape over the past two decades. Contrary to the long-held belief that the inner core is a perfect sphere, a team of scientists led by Professor John Vidale has proposed that its edges may have deformed by as much as 100 meters or more in certain areas, BBC reported. The research is published in the scientific journal Nature Geoscience.

Notably, the Earth is made up of four main structures: the outer crust, a semi-liquid mantle, a molten outer core, and a dense inner core. Earth's core plays a vital role in sustaining life on our planet and generates a magnetic field that shields us from the Sun's harmful radiation. The inner core rotates independently of the liquid outer core and the rest of the planet, creating a dynamic motion that is essential for maintaining Earth's magnetic field. Without this motion, our planet would be unable to support life, and would likely become a barren, Mars-like landscape. 

Article: Earth's inner core has both changed its relative rotation rate and deformed in the past few decades@forstokes @KeithKoper https://t.co/c1NJDEjQTA pic.twitter.com/NS3If2dS7t

— Nature Geoscience (@NatureGeosci) February 10, 2025

This transformation is believed to be occurring at the boundary where the solid inner core meets the scorching hot liquid metal outer core. "The most likely thing is the outer core is kind of tugging on the inner core and making it move a little bit," said John Vidale.

"It's almost science fiction to visualize what's happening on the surface of the inner core. It's a place that's so different from our day-to-day lives, with different timescales, different materials and incredible forces. And yet, we can get down there and learn more about it by just sifting through some of the latest observations," Mr Vidale added, 

The Earth's interior remains a mysterious realm, with the core located approximately 4,000 miles beneath the surface. Despite efforts, scientists have yet to directly explore the core, relying on indirect methods to study this remote and inhospitable region. 

To unravel the mysteries of the Earth's core, some researchers analyse the shockwaves generated by earthquakes as they ripple through the planet. By studying the behaviour of these seismic waves, scientists can infer the types of materials they encounter, including those within the inner core. 

The recent analysis took this approach a step further by examining seismic wave patterns from earthquakes that occurred repeatedly in the same location between 1991 and 2023. By comparing these patterns over time, the researchers aimed to understand how the inner core has changed.

Professor John Vidale who led the study found additional evidence supporting the theory that the inner core experienced a slowdown around 2010. His team also uncovered evidence that the inner core is not only slowing down but also changing shape.  The researchers suggest that the liquid flow of the outer core, combined with the uneven gravitational field, may be causing the inner core to deform. 

Professor Hrvoje Tkalcic from the Australian National University praised the paper, saying it presents "an interesting concept that should be explored further." He said it could allow scientists "to make more informed estimates of some important material properties, such as the viscosity of the inner core, which is one of the least known quantities in modern science".

The inner core is slowly solidifying over time as the liquid outer core freezes onto it. However, this process will take billions of years to complete, and by then, the Earth will likely have been engulfed by the Sun. 

"In science, we generally try to look at things until we understand them. In all likelihood, this finding doesn't affect our daily lives one iota, but we really want to understand what's happening in the middle of the Earth," Professor Vidale said. He added that the changes may be connected to changes in Earth's magnetic field.