Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2011 September 20



Kepler-16b: A Planet with Two Suns

Illustrated Video Credit: NASA, JPL-Caltech, T. Pyle; Acknowledgement: djxatlanta

Explanation: If you stay up long enough, you can watch both suns set. Such might be a common adage from beings floating in the atmosphere of Kepler 16b, a planet recently discovered by the space-based Kepler satellite. The above animated video shows how the planetary system might look to a visiting spaceship. Although multiple star systems are quite common, this is the first known to have a planet. Because our Earth is in the orbital plane of both stars and the planet, each body is seen to eclipse the others at different times, producing noticeable drop offs in the amount of light seen. The frequent eclipses have given Kepler 16b the most accurate mass and radius determination for a planet outside our Solar System. To find a planet like Saturn in an orbit like Venus -- so close to its binary star parents -- was a surprise and will surely become a focus of research.