© Surachit / WikimediaEarth and atmosphere cutaway illustration.
The inner core of the Earth may be melting, scientists now find.
This melting could actually be linked to activity at the
Earth's surface, the researchers said, and added that the discovery could help explain how the core generates the planet's magnetic field.
The Earth's inner core is a ball of solid iron about 1,500 miles (2,400 kilometers) wide, about the same size as the moon. This ball is surrounded by an outer core made up mostly of liquid iron-nickel alloy, a highly viscous mantle layer and, topping it off, a solid crust that forms the surface of the planet.
As the Earth cools from the inside out, the molten outer core is slowly freezing. This is leading the solid inner core to grow at a rate of approximately 1 millimeter per year.
However, scientists now find that the inner core might be melting at the same time.
"The standard view has been that the inner core is freezing all over and growing out progressively, but it appears that there are regions where the core is actually melting," said researcher Sebastian Rost, a seismologist at the University of Leeds in England. "The net flow of heat from core to mantle ensures that there's still overall freezing of outer core material and it's still growing over time, but by no means is this a uniform process."