Cosmic ray particles with even higher energies have since been observed. Among them was the Oh-My-God particle observed by the University of Utah's Fly's Eye experiment on the evening of 15 October 1991 over Dugway Proving Ground, Utah. Its observation was shocking to astrophysicists, who estimated its energy at approximately 3.2 × 10 eV (50 J) —essentially an atomic nucleus with kinetic energy equal to a baseball (5 ounces or 142 grams) traveling at about 100 kilometers per hour (60 mph).