Earth has an 'innermost inner core', study says

It follows the discovery of a hidden layer of Earth 100 miles below the surface The innermost inner core has already been hypothesised but subject to debate New findings may improve our understanding of Earth's formation and evolution It is already well known that Earth has an inner core – a solid metallic ball made mainly of iron around 1,500 miles wide. A new study claims there's another dense ball within the Earth's inner core - an 'innermost inner core' - that is 807 miles wide. The inner core exists as a single body, with the outer core surrounding it, mantle surrounding that and the crust surrounding the mantle This illustration shows seismic waves, triggered by an earthquake in Alaska, travelling through the Earth’s innermost inner core before ‘bouncing’ back to Alaska The new study was carried out by geologists at the Australian National University's Research School of Earth Sciences in Canberra, Australia. Ray paths of fivefold reverberating waves along the Earth's diameter provide a new probe to the distinct internal shell of the Earth’s inner core - the 'innermost inner core' Experts collated data from existing probes to measure the different arrival times of seismic waves of energy created by earthquakes as they travelled through the Earth.