Supernova explosions are more common than we think, with the possibility of radioactive debris reaching Earth every few million years. Recent studies show elevated levels of iron 60 in ancient sediment from two separate periods, indicating Earth was bombarded by supernova debris. This radioactive isotope, with a half-life of 2.6 million years, can only be formed in supernova explosions. The most likely culprits for these supernovas are massive stars within the Scorpius-Centaurus association, located around 390 to 470 light-years away. While the amount of iron 60 reaching Earth is minimal, the fact that debris from exploding stars is present at all is astonishing. The impact of these cosmic explosions on our planet’s history is immense, potentially affecting even our early human ancestors like Australopithecus afarensis, sparking awe and curiosity about the universe.
https://www.scientificamerican.com/article/how-often-do-supernovas-strike-earth/