The light emitted by charged particles such as protons or electrons when they pass through a transparent medium (e.g. the Earth's atmosphere, glass, or certain plastics) at a speed greater than the speed of light in that medium. The effect is the electromagnetic equivalent of a sonic boom. The radiation can occur at any wavelength, but increases in intensity with frequency and so is strongest in the blue and ultraviolet. The high-energy particles involved may be the secondary products of gamma rays or cosmic rays. For example, when gamma rays with energies of 1012 eV pass through the Earth's atmosphere they generate secondary electrons, and ground-based optical telescopes can detect the flash of blue light they emit. Cerenkov radiation is named after the Russian physicist Pavel Alexeyevich Cerenkov (1904–90).
Subjects: Chemistry — Astronomy and Astrophysics.