Friday , January 27 2023

Why did the earth become habitable, as opposed to its “twin”?


Venus may be a sweltering desert today, but scientists have questioned whether the planet was not fit to host life from the beginning. While previous studies suggested that Venus once had oceans, new research has found the opposite: Venus could probably not support oceans, according to CNN.

The researchers also determined that a similar story would have been on earth if things had been a little different. Venus, our closest planetary neighbor, is called the “terrestrial twin”, because of the similarity in size and density between the two planets.

While the Earth is a natural center of life, Venus is ill-equipped to host life with its toxic atmosphere of carbon dioxide 90 times denser than us, clouds of sulfuric acid and surface temperatures of 864 degrees Fahrenheit (462 degrees Celsius) – called Enough to dissolve lead.

To understand how these two rocky planets turned completely different, a team of astrophysicists decided to simulate the beginning, when the planets of our solar system formed 4.5 billion years ago. They used climate models – similar to what scientists use to simulate climate change on Earth – to look back in time.

The beginning of Earth and Venus

More than 4 billion years ago, both Earth and Venus were covered with magma.

Oceans can only form when temperatures are cool enough for water to condense and rain over thousands of years. This is how the Earth’s global ocean formed over tens of millions of years. On the other hand, Venus has become hotter.

At that time, our sun was 25 percent lighter than it is now. But that was not enough to cool Venus, because it is the second closest planet to the sun. Researchers wondered if clouds could play a role in helping Venus cool down.

Their climate model determined that clouds did contribute, but in an unexpected way. Clouds gather on the night side of Venus, because they could not protect the day side of the planet from the sun. Although Venus is not limited in time to the Sun, with one side of the planet always facing the star, the rotation speed is very slow.

Instead of protecting Venus from the heat, night clouds at night have contributed to the greenhouse effect, which stores heat in the planet’s dense atmosphere and keeps temperatures high. With this consistent, controlled temperature, Venus would be too hot for rain to fall. Alternatively, water can only exist in its gaseous form, water vapor, in the atmosphere.

“The associated high temperatures mean that any water is present in the form of steam, as is the case in a giant pressure cooker used for cooking,” said Martin Turbet, lead author and researcher of the study in the department. Astronomy at The Faculty of Sciences of the University of Geneva and member of the National Center for Efficiency at Research Planets, Switzerland. ».

Why didn’t that happen to the earth too?

Things would have worked for Earth in the same way if our planet was a little closer to the sun than the sun was currently as bright as it is now.

Because the sun was dim millions of years ago, the earth was able to cool enough from its molten state to form water and form our global ocean. Turbet wrote in an email that the faint young sun “was an important part of the formation of the first oceans on earth.”

“This is a complete reversal in the way we look at what has long been called the ‘faint little sun paradox,'” co-author Emeline Boulemont, a professor at the University of Geneva, said in a statement.

She went on to say, “It has always been considered a great obstacle to the emergence of life on earth. But it turns out that for a hot young earth this faint sun would actually have been an unexpected opportunity.”

Once upon a time, scientists believed that if the sun’s radiation was weaker for millions of years, the earth would turn into a snowball. Instead, the opposite was true.

The results show a variety of ways in which rocky planets have evolved in our solar system.

The Earth’s ocean exists for about 4 billion years. There is evidence that Mars was covered in rivers and lakes from 3.5 billion to 3.8 billion years ago. Now it seems unlikely that Venus will support liquid water on its surface.

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