Venus once had carbon dioxide oceans

Venus may have once possessed bizarre oceans of carbon dioxide, scientists say.
Scientists believe Venus may have harboured oceans of carbon dioxide in the ancient past that helped shape the planet's surface.
"Presently, the atmosphere of Venus is mostly carbon dioxide, 96.5 per cent by volume," said lead study author Dima Bolmatov, a theoretical physicist at Cornell University in Ithaca, New York.
Carbon dioxide can exist as a solid, liquid and gas, and past a critical point of combined temperature and pressure, carbon dioxide can enter a "supercritical" state.
Such a supercritical fluid can have properties of both liquids and gases. For example, it can dissolve materials like a liquid, but flow like a gas.

To see what the effects of supercritical carbon dioxide on Venus might be, Bolmatov and his colleagues investigated the unusual properties of supercritical matter.

In computer simulations of molecular activity, Bolmatov and his colleagues found that supercritical matter could shift dramatically from gas-like to liquid-like properties, 'Space.Com' reported.
The atmospheric pressure on the surface of Venus is currently more than 90 times that of Earth, but in the early days of the planet, Venus' surface pressure could have been dozens of times greater.
This could have lasted over a relatively long time period of 100 million to 200 million years. Under such conditions, supercritical carbon dioxide with liquid-like behaviour might have formed, Bolmatov said.

"This in turn makes it plausible that geological features on Venus like rift valleys, river-like beds, and plains are the fingerprints of near-surface activity of liquid-like supercritical carbon dioxide," Bolmatov said.
The findings were published in the Journal of Physical Chemistry Letters.