a) K2-18d
b) K2-18c
c) K2-18a
d) K2-18b
Water has been detected by scientists in the atmosphere of a potentially habitable super-Earth. The exoplanet, named K2-18b, is twice the size and eight times the mass of Earth. K2-18b is the first planet outside the solar system in the habitable zone of its star known to have water in its atmosphere.