Scientists discover new way to identify liquid water on exoplanets

The research, led by Birmingham University (UoB) and the Massachusetts Institute of Technology (MIT), suggests that a decrease in a planet’s atmospheric CO2 levels could imply that there is liquid on that planet’s surface.

According to the researchers, a decrease in CO2 levels could imply that the CO2 is being dissolved into an ocean or sequestrated by a planetary-scale biomass.

‘Habitability’ is a theoretical astronomical concept that means that a celestial body is capable of hosting and retaining liquid water on its surface, and scientists have generally agreed on which planets fall in the ‘habitable zone’, based on distances from their stars and subsequent temperatures.

The researchers devised a new ‘habitability signature’ with which they can identify whether a planet does indeed have liquid water. Previously, scientists used a planet’s glint to consider the presence of water on its surface, to measure how star light reflects off potentially present water.