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Astronomers discover third planet in the Kepler-47 circumbinary system

Astronomers have discovered a third planet in the Kepler-47 system, securing the system's title as the most interesting of the binary-star worlds. Using data from the Kepler space telescope, a team of researchers detected the new Neptune- to Saturn-size planet orbiting between two previously known planets. With its three planets orbiting two suns, Kepler-47 is the only known multi-planet circumbinary system. Circumbinary planets are those that orbit two stars. The planets in the Kepler-47 system were detected via the "transit method." If the orbital plane of the planet is aligned edge-on as seen from Earth, the planet can pass in front of the host stars, leading to a measurable decrease in the observed brightness. The new planet, dubbed Kepler-47d, was not detected earlier due to weak transit signals. Shown here: an artistic rendition of the Kepler-47 circumbinary planet system -- the three planets with the large middle planet being the newly discovered Kepler47d.

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