Today, Venus It is a dry planet. Lonely. However, scientists wonder if it could have taken refuge in an ocean in its past. See a little more like the earth. “No”, A ends Research Researchers at the CNRS and the University of Versailles St. Quentin.

Before telling you how these French scientists got there, it is good to remember that another study published by American researchers a few years ago was conceivable. Venus is covered by oceans. Climate simulations started from there, a Atmosphere It has been shown that these oceans evaporate and form, as we know them on our planet Clouds Protectors that reflect sunlight. “Especially in the so-called substellar zone, which is the time when the sun heats up the mostExplains Jerome Lecon, a researcher in the laboratoryAstronomy From Bordeaux. At the level, as happens on EarthEquator, In short “.

The work of French researchers is not really contradictory. “If there were oceans on Venus, our colleagues explain that they could be sustained, Says Jerome Leconde igs. We wondered if the oceans had formed On Venus. Our answer is no. “

What is the probability of an ocean forming on Venus?

“When they form, the planets are literally covered by an ocean Magma. A magma is highly perishable and retains a particularly dense atmosphere Carbon dioxide (CO₂) as well as Steam (H₂0). L ‘Greenhouse effect Is intense, Describes usAstronomer. Oceans can form as the planet cools to allow water vapor to condense and rain to fall. “ This is what was played on our earth.

A Climate model On the reliance of French researchers, on Venus, the American study reveals that things did not happen as envisioned by the situation. “The only place on the planet that is not too hot is at night. Also, very high in the atmosphere, on the side Stratosphere. Since Mass d We were able to get there from the daytime part filled with water vapor. Later they formed clouds, but they were localized at night. So they could not have a protective effect. They could not participate in the renewal of Venus. Worst of all, they formed a kind of heat shield that prevented the planet from cooling. It could not rain. No ocean could be formed. “

“If we imagine that there are oceans on Venus like a coin toss, the American study tells us that if the coin falls on its side, it’s only good that it’s likely to stay there., Continues by Jerome Lecon.

Gather information about other planets

Astronomers now want to understand what this study has to offer Exoplanets. They want to fix water boundaries well Liquid. “Knowing that there was never an ocean on Venus gives us a valuable clue, Points out Jerome Leconde. Our work leads us to consider if our earth was born around us Star As our sun is today, it may not be cool enough to form oceans. Thus, an exoplanet located at the same distance from us as our star may not contain oceans. Just change his star a little bit – As is the case Red dwarfs, The host stars of the most famous exoplanets – So this planet could never cool down enough. ”

Answering the question of Venus’ underground oceans can also provide crucial information about the future of our planet. “Studies have already shown that the earth can withstand a billion years – A period to be more precisely defined –, Lose his oceans, Explains the astronomer. In the past, Venus received some energy from the Sun. Because of the nature of our star, it is growing Brightness over time. A small part of what our planet is getting today. In the future, the Earth will receive more energy from the Sun, as it does from Venus today. Thus, by studying the past of Venus, we can expect to know when our planet will lose its oceans. “

To confirm their results, French researchers will wait for data that can be collected on the site via missions to Venus soon. We know that there is water vapor in the atmosphere of this planet. But short of being amazing. Can’t even imagine the oceans a few centimeters deep. We believe that at some point in history there was a lot of water in the atmosphere of Venus. But, she escaped into space, behind the needOxygen To create this oxidized atmosphere as we know it. “, Explains Jerome Lecon.

One can imagine that new missions to Venus could measure the chemical composition of its atmosphere and the isotopic structure of some of its elements. For example, this is one of the goals of the DAVINCI + (NASA) mission. With the idea of ​​water escape dating. If it happened at the end of the planet’s life, we could imagine that Venus was in an ocean and that when it evaporated, when the sun was very hot, it was water. Escape Of its atmosphere. If this had happened earlier, it would have been further evidence that Venus could never have possessed an ocean. We need to collect these kinds of clues now. “

And the Veritas Mission (NASA) Mission Envision (European Space Agency), For them, will be achieved InfraredMineral dimensions of the surface of Venus. However, some Minerals It needs water to form. Detecting their presence would be a strong indication of the presence of liquid water on the planet’s surface. In this case, we do not have to explain the stability of the oceans Remember, this was done by an American study –But how did water vapor condense at the beginning of Venus’ history?, Emmanuel Mack, a researcher at the University of Versailles St. Quentin, author of the study, informs us of the findings.