Washington, Aug 29 (IANS): Astronomers have spotted the first-ever multi-planet solar system orbiting a binary star, with the help of two telescopes in Texas.

The discovery by astronomers from Texas-Austin and San Diego State Universities proves that whole planetary systems can form in a disk around a binary (twin) star.

Measurements of the star's orbits from McDonald's Observatory showed that daylight on the planets would vary by a large margin over the 7.4-earth-day period as the two stars completed their mutual orbits, each moving closer to, then farther from, the planets (which are themselves moving), the journal Science reports.

"It's Tatooine, right?" said McDonald Observatory astronomer Michael Endl.

"But this was not shown in 'Star Wars'," he said, referring to the periodic changes in the amount of daylight falling on a planet with two suns, according to a Texas statement.

(Tatooine is name of the first planet in the binary Tatoo star system of the film series "Star Wars").

"The challenging thing is that this is a very faint star, about 6,000 times dimmer than can be seen with the naked eye," Endl said.

The binary star is called Kepler-47. The primary star is about the same mass as the sun, and its companion is an M-dwarf star one-third its size. The inner planet is three times the size of earth and orbits the binary star every 49.5 days, while the outer planet is 4.6 times the size of earth with an orbit of 303.2 days.

The outer planet is the first planet found to orbit a binary star within the "habitable zone," where liquid water could exist and thus create a home for life.

However, the planet's size (about the same as Uranus) means that it is an icy giant, and not an abode for life.

The combination of observations from the NASA mission and McDonald Observatory allowed astronomers to understand the characteristics of Kepler-47's two stars and two planets.