Ever since astronomers first learned that our planet is not the center of the Universe and that Solar System is merely a drop in the cosmic bucket, people have wondered if there could be intelligent life out there. Over time, our focus has shifted away from neighboring planets and onto neighboring stars and galaxies.

And yet, all attempts to find evidence of intelligent life have come up short. Or, at least, they've failed to provide definitive evidence that intelligent life is out there and looking to communicate with us. But considering how our technology (and our frame of reference) has been limited over time, it's possible that we simply weren't listening properly.

In the history of the Search for Extraterrestrial Intelligence (SETI), there have been a number of "candidates" (potential extraterrestrial signals), or unexplained phenomena that merited follow-up investigation. While most were attributable to natural cosmological events, there were a few that were never fully explained.


Years later, scientists still puzzle over mysterious faraway signals, dimming stars, fast radio bursts, and even an interstellar object that defied classification. Recently, scientists also discovered a signal that appeared to be coming from the neighboring star system of Proxima Centauri (and even appeared to be coming from one of its planets!)

Could it be that extraterrestrial intelligence (ETI) has attempted to communicate with us, and we simply didn't know it? Perhaps! All we know for sure is that when a "candidate" arises, scientists must eliminate all other possibilities before making any claims.

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