In one of the most significant exoplanet discoveries to date, NASA just announced that not one, but seven Earth-sized planets have been found orbiting the habitable or 'temperate zone' of a star just 39 light-years away.

Research suggests at least the inner six planets appear to have Earth-like masses, are made of rock, and have surface temperatures ranging between a life-friendly 0 to 100°C (32 to 212°F). NASA is calling it a 'sister solar system' to our own, and says several of the planets could potentially host liquid water, and maybe even extraterrestrial life.