Today's Venus may be a suffocating wasteland, but scientists have wondered if the planet was always so inhospitable. Previous studies have said that Venus is covered by deep blue oceans, the results of a new study are the opposite: Venus likely never can support oceans.
Venus, our nearest neighbor, is called Earth's twin because of the similarity in size and density of both planets. Just a little dissimilarity will make the two planets become completely different.
While Earth is the natural center for life, Venus is the opposite of a death-only planet with an atmosphere filled with toxic carbon dioxide. The sulfuric acid clouds and surface temperatures reach 462 degrees Celsius - hot enough to melt lead.
To understand how these two rocky planets evolved so differently, a team of astrophysicists decided to try to simulate the beginnings when the planets in our solar system began to form 4.5 billion years ago. They used climate models to look back in time to young Venus and Earth.
The "kiln" period:
More than 4 billion years ago, Earth and Venus were both furnaces, covered with magma everywhere. Meanwhile, the condition for ocean formation is that the temperature must be cool enough for water to condense and fall as rain for thousands of years. What secret has helped Earth have an ocean and Venus has to stay in place.
At that time, our sun was about 25% dimmer than it is now. But that won't be enough to help Venus cool, since it's the second-closest planet to the sun. So scientists wondered if the clouds could help Venus cool down.
Their climate model determined that clouds did contribute, but in an unexpected way. They gather on the night side of Venus, where they cannot shield the day side of the planet from the sun. Although Venus is not locked to the sun, and even faces a star on one side, the reason it never cools down is its extremely slow rotation.
Instead of shielding Venus from the heat and giving water vapor time to condense, night-side clouds contribute to the greenhouse effect, a dense atmosphere that keeps temperatures very high. With steady heat trapped for so long, Venus has become too hot to rain.
"The high temperature means that water can only exist as a gas, steam like in a giant pressure cooker," said Martin Turbet, lead author of the study and a researcher in the Department of Astronomy in the Department of Science. and the University of Geneva, said in a statement.
Why is Earth different?
Things could go the same way for Earth if our planet were a little closer to the sun or if the sun was as bright as it is now.
Because when the sun was dim billions of years ago, the Earth had enough time to cool down from its molten state, gradually water was formed and created the global ocean. Turbet wrote that the "weak young sun" was the key to the Earth's ocean formation.
“This is the complete reversal of the 'fading young sun paradox'. It has always been considered the greatest return to life-forming Earth, but it turns out that when the blue planet was young and very hot, such a sun was crucial to life," said Emeline Bolmont, co-author of the study. study author and professor at the University of Geneva.
Previously, scientists believed that if solar radiation were weaker than billions of years ago, the Earth would turn into a snowball. But the truth is quite the opposite. Studies also show that the rocky planets in the solar system have evolved in different ways.
Earth's oceans have existed for nearly 4 billion years. There is evidence that Mars was once covered with rivers and lakes between 3.5 billion and 3.8 billion years ago. But for now, there is little chance of Venus becoming a second Earth.
Not only for the solar system, the above research can also apply to exoplanets (planets outside our solar system).
"Our results have strong implications for exoplanets because they show that most of the planets thought to be capable of forming oceans fail to condense water," Turbet said. .
This is especially important for exoplanets around low-mass stars like TRAPPIST-1, which will be a key target for NASA and ESA's James Webb Space Telescope, launching study in December of this year.
The upcoming journeys to Venus will help test the theory put forward by Turbet and his team. “Our results are based on theoretical models and are an important foundation for answering this question. But it takes observation to determine the problem definitively! Let's hope that future space missions EnVision, VERITAS and DAVINCI+ will give us definite answers , " he stated.
The aforementioned NASA and European Space Agency mission, to be launched later this decade, could help scientists understand the most primitive surface feature on Venus called 'tesserae'. - holds evidence regarding the presence or absence of liquid on this planet," Turbet said.
