2. Technosignatures
Technosignatures are telltale clues of advanced technology at work—think artificial city lights, radio leakage, or even pollution in a distant planet’s atmosphere. Finding these signatures would offer compelling evidence for intelligent life beyond Earth. Powerful observatories, including the James Webb Space Telescope, are now scanning exoplanets for such markers. Even a trace of industrial chemicals where none should exist could point us toward a civilization making its mark on the cosmos.