23K views · 588 reactions | #OnThisDay in 1904, Pavel Cherenkov was born. He's the man who first discovered what this blue glow was surrounding a reactor core. Today it's called Cherenkov radiation — a phenomenon that happens when electrically charged particles, such as protons or electrons, travel faster than light in a clear medium like water. #nuclear #cleanenergy | U.S. Department of Energy Office of Nuclear Energy | Facebook