Video: Two Suns Set on Alien World

Credit: NASA/JPL-Caltech

This video may be the closest you come to a visit with a real-life Tatooine. Astronomers have discovered the first planet that, like Luke Skywalker's fictional home world in Star Wars, orbits two suns. The stars are a binary pair: They are about 1.5 and 4.5 times smaller than our own sun, and they orbit each other every 41 days, causing brightness dips that have been detected by the Kepler space telescope. Kepler also spied additional dips, produced when a Saturn-sized planet transits across the stars every 229 days. Both stars and planet orbit in the same plane, suggesting they formed together from a single spinning disk of gas and dust, researchers report today in Science. Until now, astronomers weren't sure whether or not planets would be able to form around binary stars. In particular, they thought that when the stars were in an eccentric orbit, as is the case here, they would strongly perturb dust particles that might prevent their coalescence into larger bodies. Kepler was lucky to find the Tatooine planet: Because of our slowly changing view of the system, there will be no planetary transits visible between 2018 and 2042.

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