One planet orbiting two stars is an image familiar from Star Wars - but now Nasa says they've discovered one for real.
The space agency's Kepler mission has found the first solar system in which multiple planets orbit two suns.
The system, which is located in the constellation Cygnus, about 4,900 light years from Earth, proves that more than one planet can orbit multiple stars.
One of the stars is similar to our own in size, but is only 84% as bright. The other is much smaller - about one-third the size of our sun and 1% as bright.
Around those stars orbit several planets. The inner planet, 'Kepler-47b', moves around the stars every 50 days. The outer planet - Kepler-47c - orbits every 303 days.
It is thought to exist in the 'habitable zone' where liquid water could exist on a planet's surface, and have an atmosphere of water clouds. However Nasa adds it is unlikely life could survive on its surface.
"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? This Kepler discovery proves that they do," said William Borucki, Kepler mission principal investigator at Nasa's Ames Research Center.
"In our search for habitable planets, we have found more opportunities for life to exist."
