Scientists find evidence of a new layer at the Earth's inner core

Researchers are still discovering more about the Earth's center. A team at Australian National University (ANU) has found evidence of a new layer to the planet sitting within the inner core. This "innermost inner core" is an iron-nickel alloy ball that, as professor Hrvoje Tkalčić explains, is a "fossilized record" of Earth's ancient history. Until now, science had only recognized four layers (crust, mantle, outer core and inner core).

The scientists found the 'hidden' core by studying seismic waves that traveled back and forth across the Earth's entire diameter up to five times — previous studies only looked at single bounces. The earthquake waves probed places near the center at angles that suggested a different crystalline structure inside the innermost layer. Effectively, the alloy is skewing the travel times for the waves as they pass through.