A high-energy particle falls from space to the Earth’s surface—it is not clear where it came from or even what it is, exactly. This may sound like something out of science fiction, but it is in fact a scientific reality.

The Amaterasu particle is perhaps as mysterious as the Japanese goddess herself. Where did it come from? What exactly was it? These questions remain. There is hope that the Amaterasu particle will pave the way for illuminating the origins of cosmic rays.

No promising astronomical object matching the direction from which the cosmic ray arrived has been identified, suggesting possibilities of unknown astronomical phenomena and novel physical origins beyond the Standard Model