It's called 'K2-18b'. Located 110 light-years away, planet K2-18b was discovered by the Kepler Space Observatory in 2015. Preliminary scans of the exoplanet suggested it was a super-Earth, that is, a rocky planet larger than Earth, and that it featured an atmosphere.
These observations warranted further study. Using the Hubble Space Telescope, a team from University College London performed a spectrographic survey of K2-18b's atmosphere, resulting in the detection of a distinctive water signature. Details of this important discovery were published on Wednesday in scientific journal "Nature".