The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou province, Nov 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)