Image credit: NASA/CXC/SAO/Science Photo Library
All signs point to a supernova. A stellar explosion 2 million years ago that flooded our neighbourhood with charged particles could be the answer to several cosmic puzzles.
For years, astrophysicists have struggled to explain why there are so many high-energy cosmic rays – speeding charged particles that hit Earth from all directions.
Anna Nowogrodzki, science writer 