Planet Kepler-16b is an extrasolar planet. It is a Saturn-mass planet consisting of half rock and half gas. The planet orbits a binary star; Kepler-16, with a period of 229 days. This is the first observationally confirmed example of a circumbinary planet. Kepler-16b is also unusual in that it falls inside the radius that was thought to be the inner limit for planet formation in a binary star system. ' According to Sara Seager, a planetary expert at the Massachusetts Institute of Technology, it was thought that for a planet to have a stable orbit around such a system, it would need to be at least seven times as far from the stars as the stars are from each other. Kepler-16b's orbit is only about half that distance.' Read more: http://www.theweatherspace.com/news/TWS-09172011_planet nasa star binary.html
