Our solar system may be unique after all, despite the discovery of at least 120 other systems with planets, astronomers said on Wednesday. All the other solar systems that have been found have big, gassy planets circling too close to their stars to allow them to be anything like Earth or its fellow planets, the British and U.S.-based researchers said. If that is the case, Earth-like planets will be very rare, the astronomers write in the latest issue of the Monthly Notices of the Royal Astronomical Society. "Maybe these other extrasolar systems ... contain only the giant planets," said Mario...