As technology and measurements have improved, astronomers have begun finding extra-solar planets at a breakneck pace. It was only last year that the first planet orbiting a binary star system was discovered. Today, NASA has announced that it has discovered a planet orbiting a binary star system that is also within the habitable zone of the system.
The planet, named Kepler-47c, orbits its two suns with a period of 303 days, and is joined by another planet in the system, Kepler-47b. The system is located 4,900 light-years from Earth and is in the constellation Cygnus. The discovery is proof that more than one planet can exist in a binary star system, a first for a circumbinary system.
"Unlike our sun, many stars are part of multiple-star systems where two or more stars orbit one another. The question always has been -- do they have planets and planetary systems?" said William Borucki, Kepler mission principal investigator at NASA's Ames Research Center. "This Kepler discovery proves that they do. In our search for habitable planets, we have found more opportunities for life to exist."
Unfortunately for Star Wars fans, no future humans will be traversing the deserts Kepler-47c digging for Krayt Dragon fossils. Astronomers say the planet is most likely a gaseous giant slightly larger than Neptune. Still, the planet could have water-vapor clouds, and its discovery will push cosmological models of star-system formation forward.
"The presence of a full-fledged circumbinary planetary system orbiting Kepler-47 is an amazing discovery," said Greg Laughlin, professor of astrophysics and planetary science at the University of California Santa Cruz. "These planets are very difficult to form using the currently accepted paradigm, and I believe that theorists, myself included, will be going back to the drawing board to try to improve our understanding of how planets are assembled in dusty circumbinary disks."
NASA has prepared a short documentary about the Kepler-47 system that can be seen below:
(Picture courtesy NASA/JPL-Caltech/T. Pyle)