The Hubble Telescope has detected water vapor in the atmosphere on an exoplanet that is 111 light years away. It is in the habitable zone, which is an area around a star where the temperature allows water to be in liquid form, and liquid water is a prerequisite for life as we know it.

"It's a clear detection of water vapor, which is very exciting because it's the first time you've done it on such a small planet," says Carina Persson, an astronomer at Chalmers University of Technology.

Red dwarf star

Previously, we have only been able to observe water vapor on large gas giant planets outside our solar system. This exoplanet, called K2-18b, is eight times heavier than the Earth and much indicates that it is a rock planet, which is Earth.

The planet orbits a so-called red dwarf star, which could be a disadvantage for life to develop.

"Red dwarf stars can shine brightly in ultraviolet light and it is fatal to us, but if there is life there it must have been developed to withstand that radiation," says Ingo Waldmann, an astronomer at University Collage London and one of the authors of the study who published in Nature Astronomy.

Running water

It is not yet known if there is life and running water on the surface, or if it is dry. The James Webb Space telescope to be sent out in two years will make more accurate observations of the planet, and only then can we know more about how great the conditions are for life on K2-18b.