223K views · 437 reactions | Why do you see a blue glow inside of a reactor? | International Atomic Energy Agency (IAEA) | Facebook

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

The Cherenkov Telescope Array Observatory (CTAO) is the world’s most powerful ground-based gamma-ray observatory. Built in collaboration with European Southern Observatory (ESO), CTAO is designed to detect the most energetic light in the universe: gamma rays. These gamma rays are released during the most violent cosmic events — exploding stars, supernovae, and extreme particle accelerators in space. Gamma rays travel across the universe at the speed of light. When they reach Earth, they collide

We are often taught that nothing can travel faster than the speed of light. This is true in a vacuum (like space). The universal speed limit, c, is unbreakable. But in a material like water, light actually slows down. In water, light travels at about 75% of its vacuum speed. This creates a loophole for high-energy particles. In nuclear reactors, subatomic particles (like electrons) are often ejected at speeds that are incredibly fast—faster than the speed of light *in water* (though still slower