About 3,200 miles down towards the center of the Earth, there is an iron-nickel ball about 760 miles in radius. Though the temperature at that depth is very high—about 5,400 degrees celsius, nearly as high as the surface of the sun and 3.5 times the temperature necessary to melt the metal at the Earth’s surface—the ball is solid due to the tremendous pressure from the mass of the rest of the Earth. But new research from geologists at Nanjing University and the University of Illinois published in Nature Geoscience suggests that there might actually be an inner-inner core—a part even closer to the center of the core, with dramatically different properties than the rest of the inner core. The difference is in the alignment of the molecules in the metal. The research suggests that in the inner core we already knew about, those molecules form a crystal structure aligned along a north-south axis that points toward the north and south poles. In the inner-inner core, however, the crystals appear to be aligned along an axis through the equator that points toward Central America and Southeast Asia. via Quartz.
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