Intriguingly, the outer planet lurks in the system's habitable zone, where a rocky planet like Earth is the right temperature to have liquid water on its surface.
"We've learned that circumbinary planets can be like the planets in our own solar system, but with two suns," said study co-author Joshua Carter at the Harvard-Smithsonian Center for Astrophysics.
Although the outer planet is probably a gas giant slightly larger than Uranus and therefore not suitable for life as we know it, these findings do show that circumbinary planets can and do exist in habitable zones.
"The thing I find most exciting is the potential for habitability in a circumbinary system," said study co-author William Welsh at San Diego State University. "Kepler-47c is not likely to harbor life, but if it had large moons, those would be very interesting worlds."
Circumbinary planets might undergo relatively wild climate swings.