Billions of Earth-Like Planets in the Galaxy Listen Download Embed Share Share this on Facebook (Opens in a new window) Share this on Twitter (Opens in a new window) Share this via Email This artist's conception shows the inner four planets of the Gliese 581 system and their host star, a red dwarf star only 20 light years away from Earth. ( Lynette Cook ) Produced by Arwa Gunja Produced by PRI and WNYC