At Dawn or Dusk, look to the sky near the horizon. You will see a bright ‘star’, called the Morning and Evening Star, which in fact is not a star, but our neighbouring planet Venus.
Venus is the second planet from the Sun. It very closely resembles Earth in terms of size and composition, that it was dubbed Earth’s Twin Sister. It is named after the Roman Goddess of Beauty. But there is nothing beautiful about a planet whose surface temperature is 462°C, with an atmospheric pressure of 92 times that of Earth. Its atmosphere consists of 96% CO² and its skies are filled with clouds of Sulphuric Acid, which lead to rains of Sulphuric Acid! If hell existed, it would be on the surface of Venus. But, there was once a time when Venus was truly Earth’s Twin, and it is believed to have had oceans of water on the surface. So how did Venus change so drastically, from Paradise to Hell?
Our journey begins 4.6 billion years ago, when a small cloud of star dust began to collapse due to gravity. Most of the mass collapsed towards the centre. The clouds of gas had such immense pressure and temperature that Nuclear Fusion was possible. Thus, hydrogen atoms were fused together at incredible rates to produce tremendous energy in the form of light and heat; a star was born. That star was our Sun. The remaining clouds of dust and rock began orbiting the infant star. Rockier chunks started orbiting closer to the Sun, and farther away, huge volumes of gas and dust accumulated together. The inner rockier chunks clashed together to form the Inner Planets; Mercury, Venus, Earth and Mars. Similarly, the outer gaseous giants were formed; Jupiter, Saturn, Uranus and Neptune.
The early age of the Solar System was very chaotic. It was marked by an event called the Late Heavy Bombardment Period. During this period, a disturbance in the asteroid belt spiralled many asteroids towards the inner planets. This led to the inner planets getting battered with asteroids. Unfortunately, for Venus, this would be the doom of its oceans. Venus was theorized to have oceans when the Late Bombardment Period began. Contrary to what you may think, it wasn’t the asteroids that stripped Venus of its water. Instead the asteroids slowed down the spin of Venus, so much so that its day is longer than its year.
The Sun is a dangerous source of high energy particles, which strike at the inner planets with vigour. Fortunately, for Earth, its magnetic field is strong enough to shield itself from these high energy particles. A rocky planet’s magnetic field arises from the speed of its rotation around its axis. Due to Venus’ slowed rotation, its Magnetic field was weakened drastically, exposing Venus to the Sun’s harmful rays. These rays stripped Venus off its Hydrogen, leading to the vaporisation of its oceans.
This led to an increase in the planet’s CO2 levels in the atmosphere. Due to the greenhouse effect, the surface temperature increased. The increase in surface temperature resulted in the release of the trapped surface carbon in the form of CO2. Thus, the vicious cycle of increased CO2 levels led to a Runaway Greenhouse Effect. The fate of Venus was officially sealed.
The Tragedy of Venus was the result of a domino effect from 3.6 billion years ago.