Seven Earth-sized planets entered the spotlight this year
Possibly life-friendly worlds orbiting TRAPPIST-1 fuel debate about what makes a habitable planet
SEVEN IN ONE GO The small, cool star TRAPPIST-1, illustrated here, hosts a bevy of Earth-sized planets. There could be many more stars like it worth studying.
JPL-CALTECH/NASA
Discoveries of planets around distant stars have become almost routine.