For the fourth time, physicists have spotted a neutrino morphing from a type called a muon neutrino to a type called a tau neutrino . The observation comes from the team working with a massive particle detector called Oscillation Project with Emulsion-tRacking Apparatus (OPERA) in Italy's subterranean Gran Sasso National Laboratory. OPERA (above) took data from 2008 to 2012 and created quite a sensation in September 2011, when it announced (mistakenly) that neutrinos fired from the European particle physics lab, CERN, 730 kilometers away in Switzerland, appeared to travel faster than light . But OPERA's main goal was to spot muon-neutrino-to-tau-neutrino conversion, which was predicted by theory. We may not have heard the last of OPERA: Researchers still have data in the can—and they've issued a press release with each tau neutrino they've seen.