This is because cosmic rays consist of electrically charged particles, meaning as they journey billions of light-years from their source to Earth, they are repeatedly deflected by the magnetic fields of galaxies, making their sources impossible to spot.

Related: High-Energy ‘Ghost Particle’ Traced to Distant Galaxy in Astronomy Breakthrough

Some of the processes and events that launch cosmic rays also blast out astrophysical neutrinos, and these ‘ghost-like’ particles could be used as ‘messengers’ to solve this puzzle, a team of astrophysicists believes.