When most people think about the search for alien life, the first thing that usually pops into mind is SETI (Search for Extraterrestrial Intelligence). Primarily a search for extraterrestrial radio signals, another more recent facet of SETI is now looking for laser pulses as a conceivable means of communication across interstellar distances. But now, a third option has been presented: looking for sources of artificial light on the surfaces of exoplanets, like the lights of cities on Earth…
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