Kepler-47

Kepler-47 is a binary star system in the constellation Cygnus located about 3,420 light-years (1,050 parsecs) away from Earth. The stars have three exoplanets, all of which orbit both stars at the same time, making this a circumbinary system. The first two planets announced are designated Kepler-47b, and Kepler-47c, and the third, later discovery is Kepler-47d. Kepler-47 is the first circumbinary multi-planet system discovered by the Kepler mission.^[5] The outermost of the planets is a gas giant orbiting within the habitable zone of the stars.^[6] Because most stars are binary, the discovery that multi-planet systems can form in such a system has impacted previous theories of planetary formation.^[7][5]

A group of astronomers led by Jerome Orosz at San Diego State University, including astronomers from Tel-Aviv University in Israel, discovered the planetary system via NASA's Kepler space telescope in 2012.^[8] In November 2013, evidence of a third planet orbiting between the planets b and c, Kepler-47d, was announced.^[9] Later analyses of transit data from the Kepler space telescope confirmed the existence of Kepler-47d.^[10]