Astronomers have discovered the largest planet outside our solar system orbiting two stars, at a distance that would make it potentially habitable for people. The real-life Kepler-1647b is a gas giant about the size and mass of Jupiter. In addition to being the biggest known two-star planet, Kepler-1647b also has the widest orbit, circling its host stars in about 3 Earth years (approx. 1,107 days), astronomers said.

Kepler-1647b also resides in its stars' "habitable zone," the range of distances at which water can exist in liquid form on a world's surface. This planet is a gas giant, so it doesn't have a surface — but any moons circling the huge planet could conceivably be capable of supporting life as we know it, study team members said.The planet was discovered by NASA's Kepler space telescope, which launched in March 2009 on a mission to determine how common Earth-like planets are throughout the Milky Way galaxy.

Kepler is a space observatory launched by NASA that spots alien planets by noting the brightness dips that are caused when the worlds cross their host star's (or in this case stars') faces from the instrument's perspective. The spacecraft generally needs to observe three such "transits" to identify an exoplanet — which means that distantly orbiting worlds take longer to find.

Kepler-1647b lies in the direction of the constellation Cygnus. The planet's two parent stars are about the same size as the sun — one is a bit bigger, and the other is a bit smaller — and they are both about 4.4 billion years old, study team members said. Nearly half of all sunlike stars are part of two-star systems. Astronomers have found planets in a number of binary systems, but such worlds had previously all been Saturn-size or smaller and had orbited relatively close to their host stars.

The study team members announced their results today (13th June 2016) at the 228th meeting of the American Astronomical Society at San Diego,California. Their paper has also been accepted for publication in The Astrophysical Journal.

Kepler's original planet-hunting observations ended in May 2013, when the second of the spacecraft's four orientation-maintaining reaction wheels failed. But scientists are still combing through the huge amounts of data gathered by Kepler, which has discovered more than 2,200 confirmed alien planets to date. The telescope also began searching for alien worlds afresh (and observing a variety of other cosmic objects and phenomena as well) in 2014, after mission team members found a way to stabilize Kepler using sunlight pressure.