If you are going to look for intelligent life beyond Earth, there are few better candidates than the TRAPPIST-1 star system. It isn't a perfect choice. Red dwarf stars like TRAPPIST-1 are notorious for emitting flares and hard X-rays in their youth, but the system is just 40 light-years away and has seven Earth-sized worlds.
Three of them are in the potentially habitable zone of the star. They are clustered closely enough to experience tidal forces and thus be geologically active. If intelligent life arises easily in the cosmos, then there's a good chance it exists in the TRAPPIST-1 system.
But finding evidence of intelligent life on a distant planet is difficult. Unless Mr. Mxyzptlk or the Great Gazoo want to talk about your car's extended car warranty, any signal we detect will likely be subtle, similar to the stray radio signals we emit from Earth.
So the challenge is to distinguish actual signals from aliens, known as technosignatures, from the naturally occurring emissions of stars and planets. Recently, a team used the Allen Telescope Array to capture 28 hours of TRAPPIST-1 signals in an effort to find the elusive aliens.
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