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Moon and Venus

StarDate: 
February 4, 2016

At the surface of Venus, the atmosphere is so thick that walking through it would be almost like walking through water here on Earth. But in the distant past, it may have been even thicker — so dense that the bottom of the atmosphere may have turned into a sort of liquid.

The planet’s atmosphere is made almost entirely of carbon dioxide. The atmosphere is so heavy that the surface pressure is equal to a depth of two-thirds of a mile in Earth’s oceans.

Under that pressure, the carbon dioxide forms a supercritical fluid — a state in which it behaves like both a gas and a liquid. Today, it’s more like a gas. But according to some recent research, when Venus was younger the CO2 could have behaved more like a liquid.

The planet’s atmosphere could have been dozens of times denser than it is today. Under that great pressure, the carbon dioxide was squeezed so tightly that it would have been more like a liquid than a gas. According to the research, the liquid could have carved valleys and other features seen on Venus today. Over time, much of the CO2 combined with other materials to make rocks, or vanished in other ways — leaving Venus with a “dry” surface.

And Venus is the brilliant “morning star” right now, shining low in the southeast at first light. Tomorrow, it’s to the lower left of the Moon. And the fainter planet Mercury is closer to the lower left of Venus, although you might need binoculars to spot it through the early twilight.


Script by Damond Benningfield, Copyright 2015

 

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