A nearby ultracool star harbors seven Earth-sized planets, three with orbits that potentially put them in a habitable zone. That makes the system, around a star called TRAPPIST-1, a prime target in the search for signs of alien life. Its discovery also hints that many more cousins of Earth may be out there than astronomers thought.
“It’s rather stunning that the system has so many Earth-sized planets,” says Drake Deming, an astronomer at the University of Maryland in College Park. It seems like every stable spot where a planet could be, there is an Earth-sized one. “That bodes well for finding habitable planets,” he says.