Who wants to go to Venus ?

Who wants to go to Venus ?
Composite photo of Venus taken by the Japanese Akutsaki probe, the Venus Climate Orbiter.

Some people think that we could live on Venus. And when the long winter nights come and the temperature drops, perhaps you might daydream about being closer to the Sun. Wouldn't “Earth's twin” be a nice place?

After all, Venus is about the same size and mass as the Earth. They formed together and had a similar early history. The pull of gravity on Venus is slightly weaker than we're used to, so it would be like losing nine pounds for every hundred that you weigh. Unspoiled by the air pollution and light pollution created by humans, wouldn't we also enjoy sunshine in clear blue skies and stargazing at night?

Let's consider that.

In which season would you visit Venus?
On Earth we have seasons because Earth's axis is tilted by 23.4°. Venus's axis has scarcely any tilt at all — it's less than 3°. Not only does Venus not have seasons, but the temperature also doesn't vary much around the planet, or even between day and night.

Earth turns once on its axis every 24 hours and takes about 365 days to orbit the Sun. Venus takes 225 Earth days to orbit and 243 Earth days to rotate once on its axis. It looks as though a day on Venus is longer than a year! However Venus rotates in the opposite direction to the direction in which it orbits the Sun. So if you were on Venus and if you could see the Sun rising and setting, one solar day would seem to take 117 Earth days. It would also seem to rise in the west and set in the east.

Why couldn't you see the sunrise?
Venus is blanketed in thick clouds. Since they're highly reflective, Venus is a bright object from Earth. But from the surface of Venus these same clouds would diffuse the Sun's light so that you couldn't see the disk of the Sun. Certainly no heavenly bodies would be visible at night. Although there's no pollution from human activity on Venus, the atmosphere is mostly carbon dioxide with enough sulfur dioxide to make the skies yellow. You'll also realize that we couldn't breathe that stuff.

But wouldn't it be great that we'd lose weight on Venus?
Yes and no. Remember that weight is the pull of gravity on our mass. We'd still be the same shape and size, though there would be a bit of a spring in your steps. Except for one thing. Although there's a minor decrease in gravitational pull, there's a major increase in atmospheric pressure.

On Earth we don't notice that a tonne of air is pushing down on each of us, because we're adapted to it. The atmosphere of Venus is much thicker than our own, and its pressure is over ninety times what we're used to. A Seawolf class submarine could withstand it, but we'd be squashed.

But Venus is nice and warm, isn't it?
Venus is certainly warm, but it's not at all nice. The lower temperatures on Venus are at higher altitudes. The highest point on the planet is the mountainous area of Maxwell Montes, but investors won't be rushing to build resorts there.

Think of days when someone gasped that “it's like an oven here”. Maxwell Montes is much hotter than your kitchen oven. It's 380°C (716 °F), and the average temperature around the planet is 460°C (860 °F), all of which is way too hot even for baking pizza. In fact, it's hot enough to melt lead or zinc.

Although Mercury is the planet closest to the Sun, Venus is hotter. Its atmosphere of greenhouse gases heats it up and the thick clouds keeps the heat in. At some time in its distant past this earthlike planet suffered a runaway greenhouse effect and lost all of its water. It only rains high in the atmosphere, but it doesn't rain water, it rains sulfuric acid. There are also lightning storms caused by volcanic action.

The wind doesn't cool things any more than your hair drier does, and close to the surface there's very little wind. This is because of the thickness of the atmosphere, but it's a different story at the cloud tops. The planet may rotate slowly, but its clouds don't. Hurricane-force winds keep the clouds whizzing around the planet in 4-5 days.

Weather forecast for Venus?
Surface: (Very) hazy sunshine. Temperature: fiendishly high. Wind speed: light breeze 5 km/hr (3 mph). Air pressure: an annihilating 90 atmospheres. Upper atmosphere: sulfuric acid rain, lightning storms, wind speed 300 km/hr (185 mph).

So how could anyone live on Venus?
About 50 km (30 mi) up into the atmosphere the temperature and pressure are similar to Earth. Some people suggest that habitats could float there like airships because they would be buoyed up by the heavier gases of the Venusian atmosphere. The concept has been studied, but so far no one is rushing into an action plan.




You Should Also Read:
Why the Sky Looks Blue
Transit of Venus - Measuring the Solar System
How to Tell a Planet from a UFO

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