Kepler-16b was the first confirmed circumbinary planet found by the Kepler mission.
Announced in 2011, Kepler-16b became the first unambiguous example of a planet orbiting two stars. Its system is often compared with the fictional world Tatooine, although Kepler-16b itself is a cold, Saturn-like gas giant rather than an Earth-like surface world.
Kepler detected the planet through transits: Kepler-16b passed in front of one or both stars and caused measurable dips in their light. The timing of those transits, combined with the stars’ eclipses, allowed astronomers to determine the system’s masses and orbits with unusual precision.
Kepler-16b circles the binary pair’s center of mass every 228.8 days at about 0.705 astronomical units. The two host stars orbit each other roughly every 41 days. A frequent mistake is calling Kepler-47c the first circumbinary planet; it is another important Kepler discovery, but Kepler-16b came earlier.