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(CNN) - It is likely that Venus has maintained stable temperatures and housed liquid water for billions of years before an event triggered drastic changes on the planet, according to a new study.
Now, Venus is a mostly dead planet with a toxic atmosphere 90 times thicker than ours and surface temperatures reaching 864 degrees, hot enough to melt lead. It is often called Earth's twin because the planets are of similar size. But modern comparisons end there.
However, a recent study compared five climatic simulations of Venus's past and each scenario suggested that the planet could withstand liquid water and a mild climate on its surface for at least three billion years. Like the other planets in our solar system, Venus formed 4.5 billion years ago.
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Those temperatures could have included a maximum of 50 degrees Celsius and a minimum of 20 degrees Celsius.
But between 700 and 750 million years ago, something caused the release of carbon dioxide from the rocks of the planet, transforming its climate.
“Our hypothesis is that Venus could have had a stable climate for billions of years. It is possible that the almost global resurgence event is responsible for its transformation from an Earth-like climate to the infernal greenhouse we see today, ”said Michael Way, author of the study at the Goddard Institute of Space Sciences. Way presented his study this week at the European Congress of Planetary Science - Joint Meeting of the Division of Planetary Sciences 2019 in Geneva.
Research suggests that Venus may have had oceans of water billions of years ago.
Previously, Way authored a 2016 study on the climate and oceans on Venus in the past.
The ocean was first suggested by NASA's Pioneer mission in the 1980s. But given its location as the second planet from the sun, Venus was not considered conducive to sustaining an ocean.
Venus receives more sunlight than Earth, which would evaporate liquid water, sending hydrogen into space and trapping an accumulation of carbon dioxide. That would lead to a continuous greenhouse effect that would create its current toxic atmosphere. The topography of Venus was completely altered by volcanic eruptions that most likely filled the lowland regions and possible ocean basins in the last billion years.
Of the five simulations, three of them included the current topography of Venus and added a deep ocean of about 310 meters, a shallow ocean of about 10 meters and traces of water on the ground. The researchers compared this with two other simulations, one using Earth's topography with a deep ocean and an oceanic world.
To recreate probable conditions on Venus that occurred 4.2 billion years ago and changed over time, solar radiation gradually increased to reflect the sun as it warmed. This also changed the weather conditions over time.
Previously, researchers believed that Venus is too close to the sun to hold liquid water on its surface, beyond the inner limit of the sun's habitable zone. The new simulations change that belief for Way and his colleagues.
“Venus currently has almost twice the solar radiation we have on Earth. However, in all the scenarios we have modeled, we have discovered that Venus could still withstand surface temperatures susceptible to liquid water, ”said Way.
Simulations suggest that Venus went through a phase of rapid cooling a few billion years after its formation. Then, the atmosphere would have been full of carbon dioxide. If Venus evolved in a manner similar to Earth, that carbon dioxide would have descended from the atmosphere, attracted by silicates, and would have been trapped on the surface. This would have allowed the atmosphere to have been filled with nitrogen with small amounts of carbon dioxide and methane, providing stability.
But something happened about 700 million years ago that remains a mystery, although researchers think it is related to volcanic activity. Magma would have released carbon dioxide into the atmosphere, and when the magma cooled, the gas could not be reabsorbed on the surface.
Whatever happens, so much carbon dioxide in the atmosphere caused a runaway greenhouse effect, evidenced in the high temperatures of the planet.
“Something happened on Venus, where a large amount of gas was released into the atmosphere and the rocks could not absorb it again. On Earth we have some examples of large-scale degassing, for example, the creation of the 500 Siberian traps. Millions of years ago, it is linked to mass extinction, but nothing at this scale. It completely transformed Venus, ”said Way.
In addition to the mystery of the cause of the event, researchers need to know how quickly Venus cooled after its formation and if there could have been water on the surface, as well as if the degassing event only occurred once or was simply one at a time. Series of events.
"We need more missions to study Venus and get a more detailed understanding of its history and evolution," Way said. “However, our models show that there is a real possibility that Venus could have been habitable and radically different from the Venus we see today. This opens up all kinds of implications for exoplanets found in what is called the 'Venus Zone', which may in fact house liquid water and temperate climates. ”
PlanetsSystem solarVenus
