Venus once shrouded in oceans of liquid-like CO2 gas, study suggests

The second planet from the Sun may once have been home to vast oceans of carbon dioxide that flew as liquid in “soap bubbles,” American researchers suggest. The oceans could have helped to create the Earth-like geological surface features of Venus.

“Presently, the atmosphere of Venus is mostly carbon dioxide, 96.5 percent by volume,” lead study author Dima Bolmatov, a theoretical physicist at Cornell University in Ithaca, New York, told Space.com.

Previous research has suggested that despite Venus’ current status as an immensely hot and dry planet, it may have once been home to enough water that an ocean of water 25 meters deep covered the planet.

However, Bolmatov’s research instead suggests that Venus may have once had oceans of supercritical carbon dioxide, that is carbon dioxide in a fluid state, held above its critical temperature and pressure.

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“This in turn makes it plausible that geological features on Venus like rift valleys, riverlike beds, and plains are the fingerprints of near-surface activity of liquid-like supercritical carbon dioxide,” Bolmatov said.

Venus has often been compared to Earth as a “sister planet” on account of its size, distance from the sun, gravity, and general mass all being similar to those here.

However, scientists believe that the surface pressure of Venus could have been far higher in the past, therefore allowing carbon dioxide to exist in this altered state. This period of heightened surface pressure could have lasted from between 100 million and 200 million years.

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Bolmatov says that his team will be undertaking further research to understand any shift from gas-like to liquid-like properties in supercritical carbon dioxide.

The gas in this different state “looked like soap bubbles…a bubble of gas that is covered by a thick layer of liquid,” Bolmatov said.

However, many things still remain uncertain about the behavior of supercritical carbon dioxide – the study has shown that supercritical matter can shift dramatically from gas-like to liquid-like properties – whereas previous research suggested the change in behaviors was gradual.