Scientists have discovered a planet not too much bigger than Earth that's circling a distant star that's much like our own sun. What's more, this planet is in the "Goldilocks zone" around that star — a region that's not too hot and not too cold. That's the kind of place that could be home to liquid water and maybe even life. The planet, known as Kepler-22b, is the first near-Earth-sized planet to...