A planet orbiting two suns - the first confirmed alien world of its kind - has been found by Nasa's Kepler telescope, the US space agency announced.

美国太空总署宣布，一颗环绕两个“太阳”运转的行星被开普勒望远镜发现，这是首次被确定的此种外部星体。

An artist's conception of Kepler-16b
It may resemble the planet Tatooine from the film Star Wars, but scientists say Luke Skywalker, or anyone at all, is unlikely to be living there.

Named Kepler-16b, it is thought to be an uninhabitable cold gas giant, like Saturn¹（土星） .

The newly detected body lies some 200 light years from Earth.

Though there have been hints in the past that planets circling double stars might exist, scientists say this is the first confirmation².

'Stunning³'

It means when the day ends on Kepler-16b, there is a double sunset, they say.

Kepler-16b's two suns are smaller than ours - at 69% and 20% of the mass of our sun - making the surface temperature an estimated -100 to -150F (-73 to -101C).

The planet orbits its two suns every 229 days at a distance of 65m miles (104m km) - about the same solar orbit as Venus.

The Kepler telescope, launched in 2009, is designed to scour⁴（擦亮，洗涤） our section of the Milky⁵ Way galaxy⁶ for Earth-like planets.

"This is really a stunning measurement by Kepler," said Alan Boss of the Carnegie Institution for Science, a co-author of the study.

"The real exciting thing is there's a planet sitting out there orbiting around these two stars."

Kepler finds stars whose light is regularly dimmed, which means there is an orbited planet between the star and the telescope.

Nasa's scientists saw additional dips in the light in both stars at alternating but regular times, confirming the dual⁷ orbit of the planet.

The finding was reported in Friday's issue of the journal Science.