Hubble telescope’s water discovery on exoplanet

This 11 September 2019 video from NASA in the USA says about itself:

With data from the Hubble Space Telescope, water vapor has been detected in the atmosphere of an exoplanet within the habitable zone of its host star.

K2-18b, which is eight times the mass of Earth, is the only planet orbiting a star outside the solar system (or “exoplanet”) within the habitable zone.

This may be the first known exoplanet with rain and clouds of water droplets. Two teams have detected signs that K2 18b has a damp atmosphere: here.

See also here.

Researchers have described a new, lower size limit for planets to maintain surface liquid water for long periods of time, extending the so-called Habitable or ‘Goldilocks’ Zone for small, low-gravity planets. This research expands the search area for life in the universe and sheds light on the important process of atmospheric evolution on small planets: here.

Why just being in the habitable zone doesn’t make exoplanets livable. Debate over what makes a planet habitable highlights the trickiness in searching for alien life: here.