Several planets in our solar system have multiple moons. But in other planetary systems the orbital dance can get far more compelling. Astronomers are finding that some faraway worlds orbit multiple suns.

Lots of stars are bound up in binaries, where two stars orbit each other. And astronomers using NASA's planet-finding Kepler spacecraft recently found two different binary star systems that each host a planet.

The idea of such circumbinary planets has been a popular one in science fiction. Just think of Tatooine, the desert world from Star Wars, with its two suns hanging low on the horizon.

The newfound planets Kepler 34 b and 35 b are gas giants about three quarters the diameter of Jupiter. One planet orbits a pair of sunlike stars; the other circles two slightly smaller stars. The details of the discovery appear in the journal Nature. [William F. Welsh et al., "Transiting circumbinary planets Kepler 34 b and Kepler 35 b"]

Counting another planet unveiled last fall, the Kepler mission has now located three circumbinary worlds. The researchers estimate that millions of circumbinary planets similar to Kepler 34 b and 35 b must exist in the galaxy. Which means science fiction is once again becoming science fact.

—John Matson

[The above text is a transcript of this podcast.] 

[Scientific American is part of Nature Publishing Group.]