Kepler Doubles its Prospects

The planet-hunting spacecraft known as Kepler has detected the first definitive exoplanet in a binary star system, and lead author Dr. Laurance Doyle has all the details on Life at the SETI Institute. He writes, "Perhaps half the stars in the galaxy are in double star systems. Understanding that planets can form in close binary systems means that these, too, can be targets in the search for habitable worlds." The twin stars have a combined mass less than that of our sun—and the planet is the size of Saturn, in an orbit as close as Venus. Fellow SETI Astronomer Dr. Franck Marchis writes, "There is no equivalent in our solar system of such a large and dense exoplanet. Kepler-16b has the same size as Saturn but a higher density, suggesting that it could be made of a core of ice/rock (half its size) surrounded by an atmosphere in a configuration similar to Saturn." In other words, having two suns doesn't automatically make a planet hot, sandy, and full of Jawas. It's all about orbiting in that "Goldilocks" zone, where the temperature is just right.

• First Planet Orbiting Two Stars Discovered by the NASA Kepler Spacecraft on Life at the SETI Institute
• Kepler-16: Exoplanets around binary star systems DO exist on Life at the SETI Institute