Planet Hunters: Billions of Habitable Planets in the Universe | Free Documentary

Are we alone in the universe? We may be very close to finding out. Planet Hunters follows the astronomers at the forefront of the search for habitable planets outside our solar system. The Kepler Space Telescope has discovered hundreds that may be Earth's twin. Scientists now believe there may be billions of habitable planets in the universe, and that extra-terrestrial life is almost certain to exist. Can we detect it?