Scientists think they solved the mystery of the Amaterasu particle

Executive Briefing & Key Highlights

The mysterious Amaterasu particle may not be a proton at all. New research suggests that some of the most extreme cosmic rays could be ultraheavy atomic nuclei, heavier than iron, which are better able to retain their energy while traveling through space. This idea could help explain how these rare particles reach Earth and provide new clues about the powerful cosmic explosions that create them.