There have been oceans on earth for almost four billion years, Mars used to be home to lakes and rivers. But experts are divided as to whether liquid water has ever eaten its way into Venus. A team led by astrophysicist Martin Turbet from the University of Geneva has now added a piece of the puzzle to the debate in the specialist magazine “Nature”.
“We simulated the climate of Earth and Venus at the very beginning of their evolution, more than four billion years ago, when the surface of the planets was still melted,” said Turbet in a statement from the University of Geneva on Wednesday. At that time, the heavenly bodies resembled a gigantic pressure cooker.
And according to the researchers, the temperatures on Venus were never low enough for water vapor to condense in the atmosphere and pour onto the planet in the form of rain. Because clouds, which formed preferentially on the night side of the planet, caused an enormous greenhouse effect, which prevented Venus from cooling down sufficiently – and thus the formation of oceans.
The European and American space agencies Esa and Nasa will send three missions to Venus over the next ten years. The observations then obtained will be decisive “to confirm our work – or to refute it,” said the Geneva professor and co-author of the study, David Ehrenreich.
“If the authors are correct, Venus has always been a hellhole,” write US researchers James Kasting and Chester Harman in an article accompanying the study. In fact, Venus is now a “hell hole”: The thick atmosphere consists mainly of carbon dioxide, the air pressure is incredibly strong and temperatures are around 470 degrees Celsius day and night.
In their simulations, the astrophysicists also showed that the earth just missed the same fate as Venus. If the earth had orbited the sun just a little closer, or if the sun had previously shone as brightly as it does today, it would now be just as inhospitable a planet as Venus.
According to the US researchers, the results also have an impact on the search for life on exoplanets: some planets outside our solar system that were considered habitable may not be, they write.
https://www.nature.com/articles/s41586-021-03873-w