Venus

Excerpt from theweek.com
By 

Despite being known for its “hellish” conditions, the planet Venus may actually have had oceans on its surface, according to a study in The Journal of Physical Chemistry Letters. The catch? Unlike Earth’s water-filled oceans, Venus’ may have consisted of a liquid-like form of carbon dioxide.

Scientists conducting research this summer found that Venus may have had enough water in its atmosphere at one point to cover the entire planet in an ocean about 80 feet deep, according to Discovery News. But because the extremely warm surface of Venus likely made it impossible for such an ocean to form, scientists concluded that instead of massive oceans of water, the planet may have once been home to oceans of carbon dioxide fluid.

The planet’s atmosphere is 96.5 percent carbon dioxide by volume, said lead study author Dima Bolmatov, and the extreme atmospheric pressure on the surface of Venus could have caused the gas to enter a “supercritical state.” A supercritical fluid “can have properties of both liquids and gases,” which Bolmatov said could have paved the way for oceans of liquid-like carbon dioxide on Venus. You can read the full study at The Journal of Physical Chemistry Letters.