[/caption] Cosmic rays are really sub-atomic particles, being mainly protons (hydrogen nuclei) and occasionally helium or heavier atomic nuclei and very occasionally electrons. Cosmic ray particles are very energetic as a result of them having a substantial velocity and hence a substantial momentum. The Oh-My-God particle detected over Utah in 1991 was probably a proton … Continue reading "Astronomy Without A Telescope – Oh-My-God Particles"