Computer gamers have identified two possible Earthlike planets outside the solar system, while playing the browser game Planet Hunter, which lets the public get data from NASA's Kepler mission and public archives and pictures.

The Web site lets citizen scientists observe light emitted by stars over a month and wait until the light curve dips in signal. A drop in luminosity, and hence the curve, suggests a possible planet transit in front of its star. The larger the planet, the greater the depth of the transit. The light curves are provided from publicly released data obtained by NASA's Kepler mission. 

NASA's Kepler Space Telescope, which was launched three years ago, is searching for signs of inhabitable planets elsewhere in the galaxy. It monitors 200,000 stars and takes pictures every 30 seconds.

According to an io9 report, citizen scientists on Planet Hunter already have discovered 69 possible planets -- two of them potentially like Earth -- which the Kepler team will take into account over time, as it is inundated and overwhelmed with the data discovered and provided by the gamers.

The findings of the citizen scientists have been published in the journal Monthly Notices of the Royal Astronomical Society.