Thanks to the Hubble Space Telescope, and the efforts of a large team of astronomers, we now know for a fact that water does exist outside of the solar system – the super-Earth K2-18b was found to contain water vapour in its atmosphere which, combined with temperatures in the vicinity of those we see on our own planet, makes it extremely exciting for researchers engaged in the search for extra-terrestrial life.
“This is the only planet right now that we know outside the solar system that has the correct temperature to support water, it has an atmosphere, and it has water in it, making this planet the best candidate for habitability that we know right now,” said lead author Angelos Tsiaras from University College London in a press conference.
Exoplanet K2-18b is located 110 light-years away in the constellation Leo, orbiting a surprisingly docile red dwarf – the most common type of star in the Milky Way Galaxy – and sporting a temperature range between –73 °C and 47 °C, which is nearly identical to the Earth’s.
That, however, is the extent of the similarities, as the planet is about 8 times more massive than the Earth, and is closer to Mars, or perhaps the Moon, in terms of surface composition – which is decidedly rocky.
Given its solid surface and water-containing atmosphere, astronomers believe that K2-18b might not only have some water on the surface, but could even harbor a global ocean that covers its entire surface area. Whether that is actually the case, however, is hard to tell at this point because Hubble is simply not up to the task of probing any deeper into the exoplanet’s atmosphere.
Based on the findings, the presence of water on K2-18b is a near certainty, but putting a finger on how much water will have to wait until the launch of NASA’s James Webb Space Telescope, scheduled for launch in 2021, and the European Space Agency’s Atmospheric Remote-sensing Infrared Exoplanet Large survey (ARIEL), to be deployed in the late 2020s.