Gamma Ray Producing Cherenkov Radiation in Earth's Atmosphere

Computer simulation of a very-high-energy gamma ray interacting in the atmosphere. Gamma rays above 100 GeV, giga electron volts, are produced near pulsars, neutron stars and super-massive black holes, and bombard Earth at a rate of about 100 million per second. The animation shows that a shower of high-energy particles (mostly electrons and positrons) is produced by the initial interaction of the gamma ray with a molecule in the atmosphere. Those particles that travel faster than the speed of light in air, emit a bluish light called Cherenkov light. Cherenkov light from gamma rays and other high-energy particles is detected by specialized ground-based telescopes, such as VERITAS, HESS, MAGIC, and CANGAROO in search of the origin of extreme cosmic particle accelerators.