![]() ![]() When Earth was formed about 4.5 billion years ago, it was a uniform ball of hot rock. The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles). The ball-shaped core lies beneath the cool, brittle crust and the mostly solid mantle. This could be related to the changing rate of solidification of the core over time, he added.Earth’s core is the very hot, very dense center of our planet. Seismic waves scatter more the deeper they penetrate the core, Koper said, indicating an increasing amount of variability closer to Earth's center. "For the first time we confirmed that this kind of inhomogeneity is everywhere inside the inner core," Guanning Pang, a postdoctoral researcher at Cornell University who conducted the research as a doctoral student at the University of Utah, said in the statement. Mysterious new substance possibly discovered inside Earth's core How has Earth's core stayed as hot as the sun's surface for billions of years? Earth's inner core may be slowing down compared to the rest of the planet ![]() In other words, the inner core didn't solidify smoothly and is made up of a patchwork of different textures. The key finding, reported July 5 in the journal Nature, was that the core's composition was "inhomogeneous," or varied. So these baby echoes and reflections are very hard to see." What we're doing is looking for a needle in a haystack. "The size is about on the order of a nanometer. ![]() "This signal that comes back from the inner core is really tiny," Koper said. There were 2,455 such earthquakes in the dataset. They focused on waves triggered by earthquakes of magnitude 5.7 or above, which are large enough to vibrate down to the inner core, sending a faint echo back to the seismometer. There is no way to access the core directly, so Koper and his team used data from 20 seismometers set up to measure earthquake waves and monitor for nuclear-weapons testing. Over time, the outer core has gradually crystallized, but scientists know little about how quickly this process has occurred, which also raises questions about the state of Earth's magnetic field over time. The churn of the metal at Earth's center is what creates the planet's magnetic field. Measuring about 1,520 miles (2,440 kilometers), this inner core spins inside the outer core, an ocean of molten iron and nickel about 1,400 miles (2,260 km) thick. Related: Earth's mysterious innermost core is a 400-mile-wide metallic ballĮarth's inner core is a solid ball of mostly iron and nickel. Not all of the iron became solid, so some liquid iron could be trapped inside." "It reached an equilibrium, and then it started to grow much more slowly. "A long time ago the inner core grew really fast," Koper said. What's more, there may be swirls of liquid iron trapped inside the solid core, study senior author Keith Koper, a seismologist at the University of Utah, said in a statement. The findings indicate that the inner core, which grows about a millimeter (0.04 inch) each year as the liquid outer core solidifies, may have grown faster during earlier times in Earth's history. New research based on the faint echoes of earthquake waves bouncing back to Earth's surface from the depths of the planet suggests that the inner core is more varied than previously appreciated. Instead, it’s a hodgepodge patchwork of solid and liquid that reaches all the way to the center. An illustration depicting the layers of Earth's internal structure.Įarth's solid inner core may not be solid after all - at least not all the way through. ![]()
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