Astronomers have announced discovery of the first circumbinary planet, a rare planet that orbits two stars, as portrayed in the sci-fi movie 'Star Wars' more than 30 years ago.

First recognized by NASA's $600 million Kepler space telescope, the rare planet is the first confirmed solar system of its kind. Named Kepler-16b, the planet is about the size of Saturn and 200 light years from the Earth.

'Star Wars' portrayed the existence of a planet called 'Tatooine' which has two sunsets. Now, it has become a reality after 34 years.

Unlike 'Tatooine,' the planet is cold, gaseous and not thought to harbor life, but its discovery demonstrates the diversity of planets in our galaxy.



This discovery confirms a new class of planetary systems that could harbor life. Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars, said Kepler principal investigator William Borucki in a NASA statement.

The existence of circumbinary planets had been previously hinted by earlier researches, but the detection now confirms such planets. Kepler detected the planet by observing transits, where the brightness of a parent star dims from the planet crossing in front of it.

The planet has two stars, one about 69 percent the mass of the Sun and the other only 20 percent the mass of the Sun, which circle each other every 41 days.

Around both of them circles the Saturn-mass planet in a period of 229 days. Even though the planet has an orbital period of less than a year, it is still outside the habitable zone of the stars as the stars are much dimmer than our Sun.

Scientists have detected the new planet in the Kepler-16 system, a pair of orbiting stars that eclipse each other from our vantage point on Earth. When the smaller star partially blocks the larger star, a primary eclipse occurs, and a secondary eclipse occurs when the smaller star is completely blocked by the larger star.

However, astronomers have observed that the brightness of the system dipped even when the stars were not eclipsing one another, hinting at a third body. The additional dimming in brightness events reappeared at irregular intervals of time, indicating the stars were in different positions in their orbit each time the third body passed. This showed the third body was circling, not just one, but both stars, in a wide circumbinary orbit.

When you have a binary star with planets orbiting that, the binary star produces gravitational perturbations that can be very severe for planets, Greg Laughlin, an astronomer at the University of California, Santa Cruz, told CNet. Planets can get tossed out of the system or tossed into one of the stars.

But Kepler-16b seems to be stable, probably because it is so far from the stars it orbits that it effectively is feeling them as a single gravitational attraction, Laughlin said.

Lead author Doyle, who is a researcher at the SETI Institute's Carl Sagan Center for the Study of Life in the Universe, explained the excitement another way.

This is an example of another planetary system, a completely different type that we've never seen before. That's why everyone's making a big deal out of it. Nobody's ever seen a place like this before, he told CNet. Then he added cheekily, With one exception -- I seem to remember seeing a place like this about 30 years ago in a galaxy far, far away.

Kepler 16b's interaction with two different suns means that temperatures on its surface can vary by about 50 degrees, between roughly minus 100 degrees Fahrenheit and minus 150 degrees Fahrenheit.