Washington, January 8 : The number of known places in our galaxy theoretically hospitable to life may be significantly greater than previously thought, researchers say.

Researchers with Planet Hunters are reporting the discovery of a Jupiter-sized planet in the so-called "habitable zone" of a star similar to Earth's sun, as well as the identification of 15 new candidate planets also orbiting within their star's habitable zone.

Within the zone, atmospheric temperatures range from -126 to +86 degrees Fahrenheit. The scientists say a rocky planet there with a greenhouse atmosphere could have pools of liquid water, and thus the possibility of life.

The discovery of the new candidate planets nearly doubles the number of gas giant planet candidates known to be orbiting within the habitable zones of solar stars.

"This is just a first step toward finding a habitable world elsewhere," Ji Wang, lead author of the study from Yale University, said.

"Any moon around this newly discovered, Jupiter-sized planet might behabitable. It's very similar to what was depicted in the movie `Avatar' -- the habitable moon Pandora around a giant planet, Polyphemus," Wang said.

Conditions on the new planet, gas giant PH2 b, and the 15 candidate planets probably could not support life, given their largely gaseous state, the astronomers said. But they could have rocky satellites that would.

Planet Hunters is a joint project of Yale University and several other institutions. It enlists volunteers to help professional astronomers detect planets outside Earth's solar system by sifting massive amounts of data gathered by NASA's Kepler spacecraft.

Professional scientists review the most promising findings. Worldwide, more than 200,000 volunteers have participated since 2010.

The latest findings also establish that Planet Hunters' volunteers are effective detectors of long-period planet candidates, or those residing in or near a habitable zone, the paper's authors said.

In all, the new paper reports the discovery of one confirmed planet, PH2 b, and 42 candidate planets. Of these, at least 15 appear to be orbiting in their star's habitable zone, researchers said.

Astronomers on the Planet Hunters team declared PH2 b to be a bona fide planet with a confidence level of 99.92 percent.

Planet Hunters volunteers typically find candidate planets by identifying faint dips in light caused by planets as they pass in front of their host stars.

In this case, professional scientists also used high-resolution spectrograph and adaptive optics to rule out false positive detections and to calculate confidence levels for their findings.

The study will be published in The Astrophysical Journal, and the findings will be presented at the 221st meeting of the American Astronomical Society in Long Beach, Calif., Jan. 6-10. (ANI)