An anonymous reader writes "Astronomers have been looking for alien worlds for more than 15 years, and now you too can join the search. The Planet Hunters project is the latest citizen-science campaign organized by the crew at Zooniverse. Hundreds of thousands of computer users are already helping Zooniverse classify galaxies through Galaxy Zoo, and analyze lunar craters through Moon Zoo. This new project aims to recruit users to check data gathered by NASA's Kepler mission, which is expected to detect hundreds of Earthlike planets in a region of the constellation Cygnus. Kepler's science team detects planets by looking for the slight dimming in a star's light that's caused when a planetary disk passing over. By making precise measurements of that periodic dimming, astronomers can figure out how big the planet is, then follow up with other types of observations to confirm its existence and estimate its mass. More than 500 planets have been detected beyond our solar system, and Kepler is just getting started."