Scientists have uncovered new evidence that suggests Earth’s inner core long believed to be a solid iron sphere may actually consist of two distinct layers. This revelation could potentially reshape our understanding of Earth’s formation and the events that shaped its early history.
“Traditionally, we’ve been taught that Earth has four main layers: the crust, the mantle, the outer core, and the inner core,” said Joanne Stephenson, a geophysicist from the Australian National University, in 2021. However, new research led by Stephenson and her colleagues indicates that Earth’s inner core is more complex, featuring an additional, even deeper “inner-inner” core.
For years, scientists have inferred what lies beneath Earth’s surface by studying seismic waves from earthquakes. These waves travel through Earth, and their paths and speeds vary depending on the material they pass through. Stephenson’s team used a sophisticated search algorithm to sift through seismic data collected over decades and found evidence that the inner core’s composition might vary significantly, suggesting a hidden layer deep within.
This newly proposed “innermost inner core” might be composed of iron with a different crystalline structure, which could hint at two separate cooling events in Earth’s early history.
“The details of this big event are still a mystery, but we’ve added another piece to the puzzle of Earth’s inner workings,” said Stephenson.
The discovery could explain discrepancies in previous experimental data and aligns with other studies suggesting anisotropy or directional differences in how seismic waves travel through the inner core. Some models suggest waves move faster along Earth’s rotational axis, while others propose the equatorial direction is faster.
While the study leaves certain questions unanswered due to gaps in seismic data, particularly from regions like the polar antipodes, the findings offer a tantalizing glimpse into the deeper stories hidden within Earth’s core. The research opens new doors for future investigations, which may further unravel the mysteries buried deep beneath our feet.
This groundbreaking study was published in the Journal of Geophysical Research: Solid Earth.
Reference: https://www.sciencealert.com/scientists-detected-signs-of-a-hidden-structure-inside-earths-core