Supernovae are the explosive end stages of massive stars. About 2.6 million years ago, one such supernova lit up Earth’s sky from about 150 light-years away. A few hundred years later, after the new star had long since faded from the sky, cosmic rays from the event finally reached Earth, slamming into our planet. Now, a group of researchers led by Adrian Melott at the University of Kansas believes this cosmic onslaught is linked to a mass extinction of ocean animals roaming Earth’s waters at the time — including the Megalodon. Earth’s inner core is probably softer than previously thought.
Seismologists from the Australian National University (ANU) have adapted a method used successfully to study the Earth’s crust and upper mantle to provide new evidence of what lies inside.
The idea of there being an inner core – a ball inside a molten outer layer – was proposed more than 80 years ago, when a Danish seismologist analysed anomalous results from seismograms following earthquakes in New Zealand.