A research team comprised of scientists from the University of Illinois and Nanjing University in China has found that the Earth’s inner core has an inner core of its own. “Even though the inner core is small–smaller than the moon–it has some really interesting features,” said Xiaodong Song, a professor of geology at the University of Illinois who just published his team’s findings in the Journal of Geoscience. “It may tell us about how our planet formed, its history, and other dynamic processes of the Earth. It shapes our understanding of what’s going on deep inside the Earth.”
The team used echoes generated by earthquakes to scan below the planet’s surface and analyzed them as they traveled through the planet’s various layers, very much in the same way that doctors use ultrasound to see inside pregnant women. In the same way that a hammer striking a bell creates seismic waves, the team’s technology gathers data not from the initial shock of an earthquake, but from the waves that resonate in its aftermath.
“It turns out the coherent signal enhanced by the technology is clearer than the ring itself,” said Xiaodong. “The basic idea of the method has been around for a while, and people have used it for other kinds of studies near the surface. But we are looking all the way through the center of the earth.”
It was previously believed that the Earth’s core was a solid ball of iron, but the team found within it a “distinct inner-inner core,” about half the diameter of the whole inner core. According to the team, the iron crystals in the outer layer of the inner core are aligned directionally, north-south, while within the inner-inner core, the iron crystals point roughly east-west. Not only are they aligned differently, but according to the team, they act differently.
“The fact that we have two regions that are distinctly different may tell us something about how the inner core has been evolving,” Xiaodong said. “For example, over the history of the earth, the inner core might have had a very dramatic change in its deformation regime. It might hold the key to how the planet has evolved. We are right in the center – literally, the center of the Earth.”
Via NBC News
Images via University of Illinois