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San Diego State University

Kepler Discovery

SDSU astronomers help reveal secrets of the universe.

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Tenth Transiting “Tatooine”

SDSU astronomers discovered the tenth known "transiting circumbinary" planet, which orbits two stars and has two suns.

About Kepler-47 Discovery

Astronomers at the International Astronomical Union meeting announced the discovery of the first transiting circumbinary multi-planet system: two planets orbiting around a pair of stars. This discovery shows that planetary systems can form and survive even in the chaotic environment around a binary star. And such planets can exist in the habitable zone of their stars.

“Each planet transits over the primary star, giving unambiguous evidence that the planets are real,” said Jerome Orosz, San Diego State University Associate Professor of Astronomy and lead author of the study which is published today in the journal Science.

This system, known as Kepler-47, contains a pair of stars that whir around each other every 7.5 days. One star is similar to the Sun while the other is a diminutive star only one third the size and 175 times fainter. The inner planet is only 3x larger in diameter than the Earth, making it the smallest known transiting circumbinary planet. It orbits the stellar pair every 49 days.  LEARN MORE

Kepler Discovery in the News

New York Times
Discovery News
Wall Street
U-T San Diego
Associated Press
National Geographic
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Previous Kepler Discoveries


Jan. 11, 2012: Using data from NASA’s Kepler Mission, SDSU astronomers announced the discovery of two new transiting “circumbinary” planet systems – planets that orbit two stars.

SDSU Media Relations
Contact: Beth Chee