Astrobiologie
Planets with very different atmospheres than Earth can also harbor liquid water for long periods of time, a new study finds. This finding suggested that the concept of planetary habitability should be reconsidered.
The team led by Marit Mol Lous from the University of Zurich modeled for the published in the journal “Nature Astronomy”. Studywhether planets with atmospheres of hydrogen and helium can enable a climate in which there is liquid water on the planet’s surface. The atmosphere of the earth also consisted mainly of these two elements in the beginning. Over time, it lost this primordial atmosphere in favor of the heavier elements oxygen and nitrogen. However, large rocky exoplanets can maintain such primordial atmospheres.
long periods
As the researchers found out with simulations, the conditions for liquid water might actually prevail on the surface of such exoplanets, provided the atmosphere is thick enough to produce a sufficiently high greenhouse gas effect. If enough geothermal heat reaches the surface, the intensive radiation from a star like the sun is not even necessary, according to Marit Mol Lous in a broadcast from the University of Bern.
According to the researcher, the results showed “that these conditions can last for very long periods of time – up to tens of billions of years.” This is an important finding, since life on Earth probably took tens of millions of years to evolve.
While the results are exciting, they should be taken with caution, said co-author Christoph Mordasini, Professor of Theoretical Astrophysics at the University of Bern: “Because for such planets to have liquid water in the long term, they must have the right atmosphere. We do not know how often this is the case.” And even under the right conditions, one does not know how likely life is to develop there. “That’s a question for astrobiology,” says Mordasini.