Star Wars' Anakin Skywalker and Luke Skywalker grew up in the fictional place called Tatooine, but real-life Tatooines, worlds that orbit two suns, do exist. Astronomers call them circumbinary planets (CBP).
Astronomers have already found a number of circumbinary exoplanets, but the discovery of another Tatooine-like world is hailed as important because this Jupiter-like world is to date the largest known planet in a twin star system. It may even have habitable moons.
Using data from the Kepler space telescope, a space observatory launched by NASA in 2009 to discover potentially habitable planets beyond the solar system, scientists found a new gas giant that orbits two stars.
The planet dubbed Kepler-1647b lies 3,700 light-years away in the constellation Cygnus. It is about the same age as planet Earth at 4.4 billion years old, but it has the size of Jupiter, which has a diameter more than 11 times that of our home planet.
The two stars, one of which is slightly larger than the other, were also found to orbit each other. Researchers said that just like clockwork, the stars eclipse each other every 11 days.
"Sometimes one will be able to see first the larger star rise or set followed by the smaller one," said Tobias Cornelius Hinse, from the Korea Astronomy and Space Science Institute.
"But, under special circumstances, one could also imagine [seeing] only one star setting or rising, when the smaller star is hiding behind the larger one during sunrise or sunset."
Another intriguing characteristic of Kepler-1647b is that it lies in the so-called habitable zone of its stars. This is the region where planetary surface can support liquid water. Water is considered a crucial ingredient to sustain life on Earth so its existence in alien worlds may possibly support life as well.
Kepler-1647b is a gas giant. It does not have a surface so extraterrestrial beings do not likely live there, but if there are moons that circle it, these could potentially be able to support life as we know it.
"This latest addition to the still-small family of CBPs defies the current trend of known short-period planets orbiting near the stability limit of binary stars," researchers reported about the discovery.
"Despite having an orbital period three times longer than Earth's, Kepler-1647b is in the conservative habitable zone of the binary star throughout its orbit."
The newly found circumbinary planet is described in a paper set to be published in the Astrophysical journal.