A study published Tuesday suggests that Earth has an additional inner core that may tell the tale of a “significant global event from the past.” The highly specialized study published in Nature found that there is a giant metal ball sitting within the Earth’s inner core, known as the innermost inner core (IMIC). The ball is roughly 800 miles, and has been part of geological theory for quite some time, but the results from the study almost conclusively prove its existence (since we can’t get down there and check with our own eyes). The study was conducted by a team...