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Astrobiology: Water is also possible on non-Earth-like planets


A new study has found that planets with atmospheres very different from Earth can also contain liquid water for long periods of time. This finding suggested that the concept of planetary habitability should be reconsidered.

The team, led by Marit Moll-Loss of the University of Zurich, is designed for publication in the journal Nature Astronomy. studyWhether planets with hydrogen and helium atmospheres could enable a climate in which liquid water exists on the planet’s surface. The Earth’s atmosphere is also mainly composed of these two elements in the beginning. 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.

long periods

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. If enough geothermal heat reaches the surface, intense radiation from a star like the Sun is not necessary, according to Marit Moll-Loss in a broadcast from the University of Bern.

According to the researcher, the results showed “that these conditions 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 tens of millions of 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: “Because such planets have liquid water in the long term, they must have the right atmosphere. We don’t know how much. Once 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.

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