China's Jiangmen Underground Neutrino Observatory (JUNO), the world's largest neutrino lab, began operations on August 26 after a decade under construction. Built 700 meters underground in southern China's Guangdong Province, it is the first large-scale, high-precision neutrino experiment facility. Nearly 700 scientists from 17 countries are joining to study neutrino mass ordering and explore neutrinos originating from the sun, supernovae, the atmosphere and Earth.