I've always wondered if we're already observing evidence of extraterrestrial civilizations, we just think it's some natural phenomenon. All of astronomy is base

I've always wondered if we're already observing evidence of extraterrestrial civilizations, we just think it's some natural phenomenon. All of astronomy is based on observation, if we mistake alien activity for a natural process it could completely screw up our understanding of what's going on. For instance, maybe Quasars are artificial super-structures, created as a power source, or a beacon to signal other civilizations (similar to the signals SETI broadcast) or something else. NOTE: I don't know nearly enough about astronomy to speculate which phenomena could be potentially artificial, but I do think it is a distinct possibility.