The charged particles in an air shower also interact with atmospheric nitrogen, causing it to emit ultraviolet light via a process called fluorescence, which is invisible to the human eye - but not to the Auger Observatory's optical detectors. Using a grid of focusing mirrors to collect the light, cameras can view the air shower up to 15 kilometers away.

Searched words: Video: Inside a Fluorescence Detector Building, Admin, webmaster@auger.org, The charged particles in an air shower also interact with atmospheric nitrogen, causing it to emit ultraviolet light via a process called fluorescence, which is invisible to the human eye - but not to the Auger Observatory's optical detectors. Using a grid of focusing mirrors to collect the light, cameras can view the air shower up to 15 kilometers away.