atmospheric Cherenkov radiation

Atmospheric Cherenkov radiation occurs when high-energy particles, like cosmic rays or gamma rays, enter Earth's atmosphere at nearly the speed of light. As they pass through air, they travel faster than the local speed of light in that medium, causing a faint, bluish light known as Cherenkov radiation. This happens because the particles disturb the air molecules, creating a shockwave of light similar to a sonic boom but in the optical range. Scientists detect this brief flash of blue light with specialized telescopes to study cosmic phenomena and high-energy astrophysical sources.