Cao Zhen (L), a researcher at the Institute of High Energy Physics (IHEP) under the Chinese Academy of Sciences (CAS), conducts maintenance with staff members at China's Large High Altitude Air Shower Observatory (LHAASO) in Daocheng, southwest China's Sichuan Province, April 28, 2019. Chinese scientists have detected a dozen ultra-high-energy (UHE) cosmic accelerators within the Milky Way, a find that could overturn humanity's understanding of the galaxy and help reveal the origin of cosmic rays, which have puzzled scientists for a century. The findings were based on the observations of China's Large High Altitude Air Shower Observatory (LHAASO), one of the country's key national science and technology infrastructure facilities, which is under construction in Daocheng, in southwest China's Sichuan Province. The new discoveries were published in Nature on Monday. Scientists have also detected photons with energies exceeding 1 peta-electron volt (quadrillion electron-volts or PeV), 100 times more energy than the record high achieved by any manmade accelerator on Earth. One photon with an energy of 1.4 PeV was detected, the highest value ever observed by humans. [Photo by Jin Liwang/Xinhua]