Liquid water is possible on planets other than Earth

A new study has found that even planets with atmospheres very different from Earth can host liquid water for extended periods of time. This finding suggested that the concept of planetary habitability should be reconsidered. Researchers from the universities of Bern and Zurich published this Monday in the journal Nature Astronomy.

The team, led by doctoral student Marit Mole-Loss, has modeled whether planets with hydrogen and helium atmospheres are able to maintain a climate that allows liquid water to exist on the planet’s surface. Earth’s atmosphere is mainly made up of these two elements. Over time, this primordial atmosphere was lost in favor of the heavier elements oxygen and nitrogen. However, large, rocky exoplanets can maintain such primordial atmospheres.

heat as a condition

As the researchers discovered through simulations, liquid water conditions can actually prevail on the surface of such exoplanets, provided the atmosphere is thick enough to create a sufficient greenhouse gas effect. Marit Moll-Loss was quoted as saying in a broadcast from the University of Bern, if enough geothermal heat reaches the surface, then the intense radiation from a star like the Sun is not necessary.

According to the researcher, the results “show that these states can persist for very long periods – up to tens of billions of years”. This is an important finding because life on Earth may have taken several million years to develop.

Co-author Christophe Mordasini, professor of theoretical astrophysics at the University of Bern, said that while the results are exciting, they should be taken with caution: “For such planets to have liquid water in the long term, they must have the right atmosphere. We don’t know how often. This happens.” And even under the right conditions, one does not know how likely life is to develop there. “This is an astrobiology question,” Mordasini says.

service: https://www.nature.com/articles/s41550-022-01699-8