The "Does human life exist beyond Earth" debate just scored another talking point with the discovery of eight new planets within the so-called "Goldilocks" -- or habitable -- zone of their stars. Astronomers with the Harvard-Smithsonian Center for Astrophysics, or CfA, announced their findings at a meeting of the American Astronomical Society. To be considered habitable, exoplanets must orbit within a distance of their stars in which liquid water can exist on the planet's surface, receiving about as much sunlight as Earth. Hence the Goldilocks zone: Too much sunlight and the water would boil away as steam, too little, and the water would freeze. Among the eight, scientists say two are the most similar to Earth of any known exoplanets to date.