A full reading of https://en.wikipedia.org/wiki/Oh-My-God_particle

"The Oh-My-God particle was an ultra-high-energy cosmic ray detected on the evening of 15 October 1991 over Dugway Proving Ground, Utah, by the University of Utah's Fly's Eye Cosmic Ray Detector.[1][2] Its observation was a shock to astrophysicists (hence the name), who estimated its energy to be approximately 3×1020 eV or 3×108 TeV. This is 20000000 times more energetic than..."