The rotation of the Earth's inner core is tied to the planet's overall rotation. Changes in the core's structure or movement can influence how fast or slow the Earth spins on its axis. Even minute ...

This inner core has intrigued researchers since its ... emerged in unexpected places — a “shadow zone,” as Lehmann called it ...

This shadow zone has led geologists to a model of the Earth with a solid mantle and a liquid core. From the diagram, we can see the region where S waves are not detected. Geologists have been able ...

Refractions between layers cause two shadow zones, where no P waves are detected – the size and positions of these shadow zones indicate there is a solid inner core.