Venus is the closest planetary neighbour of Earth and the second planet from the Sun. It is named after the Roman goddess of love and beauty, but the conditions and weather are actually quite hellish. Despite being further away from the Sun than Mercury, it is the hottest planet in the Solar System with temperatures reaching 471°C, due to the dense atmosphere that traps heat similar to the greenhouse effect. It also orbits in retrograde. Let’s explore some of the aspects of Earth’s nefarious sister.
Venus has been known to people since ancient times, since it is possible to spot it with a naked eye due to its large apparent brightness. A lot of civilisation thought of it as a star. It took until Copernicus and Galileo came onto the scene, when Venus was finally classified as a planet. Further developments happened in the 18th century. In 1761 Mikhail Lomonosov showed that the planet had a gaseous atmosphere.
To see just how similar Venus is to Earth, let’s look at some numbers. Venus has a radius of 6.051 km, and our home planet has a radius of 6,371 km. Venus has a density of 5.24 g/cm3 and Earth has a density of 5.52 g/cm3. Their masses are also similar, as Venus is around 0.85 times the mass of Earth and their volumes are respectively 928 and 1083 billion km3. Don’t let these size and density similarities fool you, since the climates are vastly different, showing the importance of the distance from a star in planetary systems.
Venus has a very thick atmosphere exerting a pressure 92 times higher than our atmosphere. It is primarly composed of carbon dioxide, with thick clouds of sulfuric acid. This makes it very difficult to observe its surface, but advanced radar systems allow us to take a peak. The surface is similar to other rocky planets, covered with dry oceans, canyons and mountains. Moreover, a significant majority of the plains are covered with volcanic rock, which is evidence for prevalent volcanic activity in the past. Some of these volcanos are theorised to have erupted in the last few hundred years.
You might think that there could not have existed life, due to the harsh climate. Yet, scientists suggest that liquid water could have existed there in the past. Pressure changes the boiling point of water, therefore liquid water could have existed at temperatures as high as 150°C. Later, as the planet warmed up, this water evaporated into the atmosphere. Some experts claim that this is too hot for the existence of life. However, extremophiles are known to live in volcanos and can exist at extreme temperatures. Some can thrive in sulphuric acid pools and some can survive in water of 120°C Therefore, who knows what could have been possible. Maybe some bacteria still live there, but that might be wishful thinking.
Another interesting aspect of Venus is the minute difference in temperature during the day and during the night. There are very high wind speeds in the upper atmosphere that can reach up to 200 mph, which were initially thought to be responsible for a rapid temperature transfer between the side illuminated by sunlight and the dark one. Nonetheless, surface winds were shown to be much less than this value. Another likely explanation is the greenhouse effect that allows the temperature to be retained even if a side is in the dark. Due to its axial tilt, the planet orbits upside down making it not experience significant seasonal changes.
Overall, Venus is a very fascinating planet mainly due to its paradoxical nature. Just like Mars, it is Earth’s neighbour, nonetheless it orbits upside down, in retrograde and is a hellish landscape straight from a science fiction horror.
References
Micropia. (n.d.). Phaser App. https://www.micropia.nl/dossiercontent/microworld/en/12/?ph=1
NASA – The Planet Venus. (2004, April 3). NASA. https://www.nasa.gov/audience/forstudents/5-8/features/F_The_Planet_Venus_5-8.html
National Weather Service. (n.d.). The Planet Venus. https://www.weather.gov/fsd/venus
Venus. (2019, September 26). The Nine Planets. https://nineplanets.org/venus/