Astronomers say they’ve found another real-life version of Tatooine, the fictional world from “Star Wars” that features two suns, and it’s the largest one yet.
The new planet is indeed far, far away – 3,700 light-years – and approximately 4.4 billion years old, about the same age as Earth. It’s about the same size as Jupiter, making it the largest planet orbiting two suns ever identified.
The newfound discovery, uncovered with the help of the Kepler telescope and known as Kepler-1647b, was identified by a team led by researchers at NASA and San Diego State University. It was presented Monday during a meeting of the American Astronomical Society in San Diego.
“It’s a bit curious that this biggest planet took so long to confirm, since it is easier to find big planets than small ones,” San Diego State astronomer Jerome Orosz, who worked on the study, said in a statement.
The researchers say the planet takes 1,107 days, or just over three years, to orbit its two suns, the longest period discovered so far.
It is also located much further away from its host stars than other circumbinary planets, as those with two suns are called. The unusual orbit also puts it in what’s known as the habitable zone, where life-sustaining water can be in liquid form. But its large size makes it an unlikely candidate to support life, the researchers say.
But binary star systems could theoretically play host to Earth-like, rocky planets as well, a pair of astrophysicists argued in a paper last year, as the Christian Science Monitor's Pete Spotts reported at the time.
They theorized that binary stars could potentially contain more rocky planets after modeling the interactions of Pluto and its largest moon Charon, which shares space with four smaller moons that orbit the two objects.
In the case of the much larger Kepler-1647b, the two stars the planet orbits are similar to our sun, with one slightly larger and one slightly smaller than our home star star, according to NASA.
To identify such circumbinary planets, which scientists also call “Tatooine” planets after the fictional home of Luke Skywalker in the “Star Wars” movies, they examined data from the Kepler telescope, looking for small declines in brightness.
Those might indicate that a planet is passing or transiting in front of a star, blocking a small amount of the star’s light.
But the intervals in between transits – when a planet passes in front of a star – can be irregular for a planet that orbits two stars, making them more difficult to identify, San Diego State astronomer William Welsh said in a statement. In addition to varying in time, the transits for a circumbinary planet can even vary in depth, he says.
Scientists found the first Tatooine planet – about the size of Saturn and located 200 light-years from Earth – in 2011. In 2009, NASA launched the Kepler telescope to hunt for planets, particularly focusing on Earth-like worlds outside our solar system.
The researchers say that while the newfound planet is a gas giant and unlikely to host life, its discovery is significant.
“Habitability aside, Kepler-1647b is important because it is the tip of the iceberg of a theoretically predicted population of large, long-period circumbinary planets,” said Dr. Welsh, of San Diego State.