... Explanation: Planet Kepler-186f is the first known Earth- size planet to lie within the habitable zone of a star beyond the Sun. Discovered using data from the prolific planet-hunting Kepler spacecraft , the distant world orbits its parent star, a cool, dim, M dwarf star about half the size and mass of the Sun, some 500 light-years away in the constellation Cygnus. ... Publications with keywords: kepler - extrasolar planet . ... Kepler Orrery IV . Kepler 78b: Earth Sized Planet Discovered . ...