Astronomers from the San Diego State University (SDSU) have discovered a planet that circles not just one but two stars just like Tatooine, the fictional planet featured in Star Wars that has two suns in its sky.

The exoplanet named Kepler-453b is what is known as a circumbinary planet, which orbits two stars. It is the tenth of its kind to be discovered.

Circumbinary planets were once thought to be rare and even impossible, but the discovery of the existence of 10 such planets provides evidence that such worlds exist and are even common.

The discovery, which will be announced at the 29th International Astronomical Union General Assembly in Honolulu on Aug. 14, is hailed as an important milestone as it brings the number of circumbinary planets to double digits. The exoplanet was discovered only four years following the discovery of the first Kepler circumbinary exoplanet.

It takes 240.5 days for the newly discovered planet to orbit its parent stars that also circle each other every 27.3 days. Kepler-453b is also located within the habitable zone, or the area around the stars marked by a temperature that is neither too cold nor too hot to support life.

"We present the discovery of Kepler-453 b, a 6.2 R planet in a low-eccentricity, 240.5 day orbit about an eclipsing binary. The binary itself consists of a 0.94 and 0.195 M pair of stars with an orbital period of 27.32 days," the astronomers who made the discovery reported.

Stephen Kane, from the San Francisco State University, who is part of the team that made the discovery, said that there could be more planets like Kepler-453b than previously believed.

The astronomers said that the tilt of the planet's orbit rapidly changes, which makes transits visible only 9 percent of the time. They said that they were lucky to detect the planet since transits are not often visible from the vantage point of the earth.

The change of orientation of the orbital plane of Kepler, a phenomenon known as precession, brought it into the right alignment, which allowed three transits to be observed.

Kane said that had they been observing the area where the planet was located any earlier or later, chances are they would not have been able to see anything and would assume that no planet was in the vicinity.

If the researchers did not discover the new planet now, the next opportunity for scientists to spot it would be after more than 50 years.

Kepler-453b is described in the study published in the Astrophysical Journal on Aug. 5.

Photo: European Southern Observatory | Flickr