Scientists for the first time have detected water in the atmosphere of an Earth-like planet orbiting a distant star, evidence that a key ingredient for life exists beyond our solar system. Water vapor was found in the atmosphere of K2-18b (pictured in artist's impression), one of hundreds of "super-Earths" - worlds ranging in size between Earth and Neptune - documented in a growing new field of astronomy devoted to the exploration of so-called exoplanets elsewhere in the Milky Way galaxy.