Inner core of Earth found to be surprisingly softer than a solid metal sphere

Earth’s inner core might be as soft as butter due to shifting iron atoms.

Key Takeaways

1. A new study reveals Earth’s inner core is softer, like butter, rather than solid metal.
2. The discovery challenges the long-held belief that the inner core is a rigid iron sphere.
3. Seismic wave analysis and advanced modeling suggest iron atoms can move within their pattern.
4. Understanding the core’s behavior could help explain Earth’s complex and shifting magnetic field.
5. This research highlights how dynamic processes deep within the Earth protect life on the surface.

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A groundbreaking study has upended the traditional notion that Earth’s inner core is a hard, solid iron sphere. Published in the Proceedings of the National Academy of Sciences, the research shows that the planet’s core may instead resemble a gooey, butter-like structure, with iron atoms capable of shifting within their hexagonal arrangement.

For decades, scientists believed the extreme pressure at the Earth’s center forced iron atoms into a solid state. This core was thought to be a massive, stationary iron ball encased within the outer molten core. However, recent findings paint a more complex picture, with seismic wave patterns and laboratory experiments challenging these assumptions.

Revealing the Inner Core’s Behavior

The study recreated the intense pressures and temperatures of the Earth’s inner core using advanced computer modeling and lab simulations. Researchers confirmed that iron atoms form a hexagonal pattern at the core but discovered an unexpected twist: the atoms can move within this structure. Lead author Youjun Zhang from Sichuan University likened the core’s consistency to softened butter, where the atoms “shift around like guests at a dinner table.”

This revelation builds on earlier findings that questioned the traditional “solid core” model. Seismologists had noted discrepancies in the way earthquake shockwaves travel through the core, which didn’t align with the idea of a completely rigid structure. Instead, these waves suggested a more fluid and dynamic environment.

Jessica Irving, a seismologist from the University of Bristol, remarked in 2021 that the inner core wasn’t just a “boring blob of iron.” The new research expands on this idea, showing that the inner core’s softness allows it to adapt and respond in unexpected ways.

Implications for Earth’s Magnetic Field

The study’s findings could help solve enduring mysteries about Earth’s magnetic field, which protects the planet from harmful space radiation and helps maintain the atmosphere. The magnetic field is generated by the movement of molten metal in the outer core. However, its behavior is far from simple: it shifts unpredictably, occasionally reverses direction, and has unexplained anomalies.

Understanding the gooey nature of the inner core could provide crucial insights into these magnetic complexities. Jung-Fu Lin, a professor at the University of Texas and co-author of the study, emphasized the importance of these findings for understanding the inner core’s dynamic processes and evolution.

By shedding light on the planet’s innermost workings, this research not only deepens our understanding of Earth’s geology but also enhances our ability to protect life on the surface from cosmic threats.