The TRAPPIST-1 system, located about 41 light years from Earth, has been a focal point of much exoplanetary discussion—mainly because it has seven confirmed planets orbiting a dim M-dwarf star. Two of those planets—TRAPPIST-1e and -1f—are thought to be in the star's habitable zone. However, th e habitable zone of M-dwarfs is so close to the star itself, the planets are likely tidally locked to it, meaning they have a permanent day and night side, with a "twilight terminator" in between. ...read more read less