The original "Star Wars" presented to the world an unforgettable vision: Luke Skywalker standing on his home planet of Tatooine with two setting suns.
In reality the vision is hardly fantastic; binary star systems are not rare. But it took Kepler to discover the first known planet orbiting two suns.
The planet is not Earth-like – or even Tatooine-like. It appears to be more like Saturn – much more massive than Earth and orbiting its primary star at a distance of about 65 million miles, similar to Venus's orbit in our solar system. The secondary star orbits the primary star at a distance of about 25 million miles.
Before the discovery of Kepler-16b, scientists suspected that planets might form in double-star systems but had no proof.
The larger, central star in the Kepler-16 system is 70 percent the mass of the sun, while the smaller star is only about 20 percent of the sun's mass. These dynamics mean that despite Kepler-16b's orbit, it only receives as much sunlight as Mars.
And those sunsets?
If Kepler-16b has moons, the view could be spectacular, "with the largest orb glowing orange, the other red, and their own orbital dance ensuring no two sunrises and sunsets are ever the same," wrote the Monitor's Pete Spotts at the time of the announcement in September 2011.
