Researchers confirm discovery of Earth's inner, innermost core

3D illustrations of the Earth’s inner core structure and the texturing of its iron crystals. The transparent outer surface is the inner core boundary (at radius 1220 km). The opaque inner sphere is the inner inner core (slightly less than half of the inner core radius) found in this study. The sticks represent the alignments of iron crystals in the outer part of the inner core. The longer the stick is, the higher the degree of alignment is and the stronger the seismic anisotropy is. The fast direction is parallel to the spin axis. This illustration is a 3D view. The labels NP and SP stands for the North Pole and the South Pole, respectively. The anisotropy at the top 100 km is weak. The anisotropy at greater depth is stronger in the western part than in the eastern part. The form of anisotropy in the inner inner core is different from that in the outer part. Credit: Illustrations by Precision Graphics