What we can learn from planet Venus 

What we can learn from planet Venus 

Venus is the brightest of wandering stars, the planet is so bright one can not miss it. It is always viable near the setting or rising sun and never wanders more than 47 degrees away from the Sun. When it is visible in the morning Greeks initially called it star Phosphorus and when visible in the evening they called it Hesperus star. It was the famous Mathematician Pythagoras who released it as the same wandering ‘star’, a planet in the sixth century.  In the second century Ptolemy in his Almagest, an encyclopaedia of Greek astronomy proposed that both the Mercury and Venus are located between Earth and the Sun.

Nicolus Copernicus set out to find an elegant model of the universe where retrograde motions of the planet have a simpler solution.  Change in Venus’s brightness is maximum compared to all the planets, to explain it Copernicus has to make the orbit of Venus so large it was practically going around the Sun. This observation encouraged him to propose a Heliocentric model of the Solar system over an ancient geocentric one. One oblivious observational consequence of the Copernicus Heliocentric universe was that Venus should show a phase like the Moon if it goes around the Sun.

This is exactly what Galileo Galilei observed when he pointed his telescope towards Venus. He saw it looked like a tiny crescent Moon, further observations confirmed changing phases from crescent to half and then gibbous to full and shrinking to smaller size as if it is moving from front it is moving to the side and then going behind the Sun. It was exactly as predicted by the Coppenrnicus’s heliocentric model. This was the first direct observational evidence of a planet going around the Sun.

Even using the most powerful optical telescope, apart from changing phases and changing size and brightness we can not see anything else on Venus. By the late 18th century  it became clear that it was covered by some kind of clouds. Its atmosphere is revealed to 96.6% Carbon dioxide 3.5% nitrogen and traces of sulphur dioxide. Apart from this at the surface of Venus, the pressure of the atmosphere is 93 times that of the Earth. As a result of this, conditions on our Earth’s twin planet Venus are similar to mythical hell. Its average temperature is 464 degree C and atmospheric pressure is hundreds times that of Earth.  So one if plans to visit this planet in near future be ready to be poisoned by sulfuric acid fumes crushed by atmospheric weight equal to three hundred elephants and finally roasted by its unbearable heat. And finally there is not a drop of precious water to quench your thirst. Current climate of earth is decorticating so fast due to increasing Carbon di-oxide released by burning fossil fuel it might become an inhabitable planet if not a hell like Venus in future.

When the solar system was forming Venus must have looked like a ‘twin’ of earth as both are same in size. Both started with a thick atmosphere and must have ample water to start with. Earth and Venus both were impacted by a large probability of a Mars size protoplanet. Something that went different with Venus was the high velocity of this impact. As a result its axis of rotation was tilted by 177.36 degrees where the tilt of the earth axis is only 23.5 degrees. As a result it is the only planet that has its North Pole points in the direction where earth and solar systems’ south pole points, in other words it appears to rotate clockwise or retrograde. Second Thing that happened was that its rotation slowed down so much that it takes 243 earth days  to  rotate once whereas it takes 224.701 earth days to orbit the Sun.

but what went ‘wrong’ with Venus so it became a hellish planet is not resolved. It might simply be that slow rotation causes more time for its surface to face the sun causing more heating and being more close to the Sun means more heat coming from the Sun.  Maybe a thick atmosphere having little more carbon dioxide compared to earth could trigger the start of a runaway greenhouse effect. Once temperature hit the critical point most of the carbon dioxide from the crust was released in the atmosphere and global warming reached a point where all the water was lost to space Venus  potential to become habitat for life. On earth green plants, especially blue green bacteria and algae in the ocean, plays an important role in removing carbon dioxide from the atmosphere. If earth average temperature is read by 5 degree from the pre industrial age all the ocean blue green bacteria and ocean algae will be dead. Once this tipping point is reached, the greenhouse effect produced by carbon dioxide and methane might push our Earth in the path once taken by its ‘twin sister’ Venus. I don’t think anyone wants that to happen. We are already halfway in that direction as Earth average temperature has increased by 1.5 degree from pre industrial average. At the current rate of increasing greenhouse gases it might happen in the next 50 years. Or we have already crossed pints of no return on the way to making our ‘Garden of Eden’ in to a man made hell!

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