Venus is often considered the ‘twin’ of Earth, due to its closeness and similar size to our planet but, beyond that, the differences between the two worlds are more than remarkable. Currently, Venus contains a very dense atmosphere of carbon dioxide , extreme temperature and pressure conditions, as well as dense clouds of sulfuric acid.
Although Venus is currently a planet not very conducive to life, there are many unknowns about its past, and one of the most accepted hypotheses is that more than 4 billion years ago Venus may have contained a large ocean of surface liquid water.
Now, a new study published in the journal Nature , and that will surely give much to talk about, shows the results of a climate simulation that indicate that the conditions of the past would not have allowed the formation of oceans on the surface of our twin. The results are purely theoretical and it is hoped that future space missions to Venus could shed more light to help corroborate or refute these data.
The team of astrophysicists, led by the University of Geneva (UNIGE) and the National Center for Research Competence (NCCR) PlanetS, Switzerland, used three-dimensional models of the atmosphere, similar to those used to simulate Earth’s current climate. , to study the evolution of the atmospheres of both planets and analyze whether the conditions necessary for the formation of oceans were present.
“We simulated the climate of the Earth and Venus at the beginning of their evolution, more than four billion years ago, when the surface of the planets was still molten,” explains Martin Turbet, one of the authors. ” We found extremely high temperatures that indicate that the water would have always been in the form of vapor, as if it were a gigantic pressure cooker .”
“Thanks to our simulations, we were able to show that weather conditions did not allow water vapor to condense in Venus’ atmosphere,” explains Turbet. This means that temperatures never dropped low enough for the water in its atmosphere to form raindrops that could fall on its surface. Instead, the water always remained in the form of gas and the oceans never formed. “One of the main reasons is the clouds that preferentially form on the night side of the planet. These clouds cause a very powerful greenhouse effect that prevented Venus from cooling as fast as previously thought ”, continues the Geneva researcher.
Small differences with serious consequences
Surprisingly, astrophysicists’ simulations also reveal that Earth could easily have suffered the same fate as Venus. If the Earth had been a little closer to the Sun, or if the Sun had shone as brightly in its “youth” as it does today, our home planet would look very different today. It is likely that the relatively weak radiation from the young Sun allowed the Earth to cool enough to condense the water that makes up our oceans.
For Emeline Bolmont, another of the authors, this finding involves totally inverting previous beliefs: “It has always been considered that a young and weak Sun could have been a great obstacle to the appearance of life on Earth,” she explains. The argument was that if the radiation from the Sun had been much weaker, the Earth would have turned into a ball of ice hostile to life. ” But it turns out that, on the contrary, for a young and very overheated Earth, this weak Sun could have been, precisely, an unexpected opportunity .”
Data that need to be confirmed
“Our results are based on theoretical models and are an important pillar in answering the question of the history of Venus,” says study co-author David Ehrenreich. “But we will not be able to give a final verdict on our computers. The observations of the three future space missions of Venus will be essential to confirm or refute our work ”, acknowledges the researcher.
Referencia: Turbet, M., Bolmont, E., Chaverot, G. et al. Day–night cloud asymmetry prevents early oceans on Venus but not on Earth. Nature 598, 276–280 (2021).
