Extreme Telescope

Stars rotate behind two of the five dishes that make up the High-Energy Stereoscopic Survey telescope (HESS) in Namibia. The dish at right, HESS II, spans about 90 feet, and was dedicated in September. The other is one of the four smaller dishes of HESS I. The telescopes look for brief flashes of blue light created when gamma rays strike particles in the upper atmosphere. These flashes of light can reveal details about the origin of the gamma rays, which are produced by some of the most powerful objects and events in the universe. [HESS Collaboration/Clementina Medina/Irfu-CEA]