Scientists discover a real-life Tatooine orbiting two suns

Astronomers have found more real-life versions of Luke Skywalker's home planet Tatooine from "Star Wars" — alien worlds that see two suns rise and set each day instead of one. And these two newfound worlds are also extremely close to the habitable zones of their parent stars, scientists say.

The discovery cements what appears to be a new class of twin sun alien planets and may help astronomers estimate how many of such binary stars possess planets. The finding also suggests that many planets might lie in the habitable zones of such systems, researchers said.

Astronomers used NASA's Kepler space telescope to identify the two so-called "circumbinary planets" amid 750 systems they sampled. Their discovery brings the total number of confirmed double-sun worlds up to three.

Two worlds, four suns

Both newfound twin-sun planets are low-density gas giants located around distant star pairs. [Gallery: "Tatooine" Planets With 2 Suns Found]

The first, called Kepler-34 b, is about 22 percent of the mass of Jupiter (the largest gas giant in our solar system) and 76 percent the width of Jupiter. Kepler-34 b orbits two sunlike stars once every 289 days at about the same distance as Earth is from the sun. The planet is located about 4,900 light-years from Earth.

The second planet, called Kepler-35 b, orbits two stars that are 5,400 light-years from Earth. It has about 13 percent the mass of Jupiter and is 73 percent as wide. It and orbits its parent stars, which are slightly smaller than the sun, once every 131 days from a distance about 60 percent that between Earth and our sun.

These orbits place these planets very near the habitable zones of these stars — that is to say, it is neither too hot nor too cold for liquid water to form on a planet's surface in these regions, meaning that life as we know it could in principle gain a foothold there.

"With only three circumbinary planets known, we are already very close to that special 'Goldilocks' zone," study lead author William Welsh, an astronomer at San Diego State University, told SPACE.com "It is my opinion that circumbinary planets in the habitable zone will turn out to be fairly common, and that is exciting."

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