Planet profile Venus
What’s happening at Earth’s evil twin
Hell on Earth’ is a phrase used by many, but one planet actually matches this idea of a harsh and inhospitable environment; that accolade falls to Venus. The second planet from the Sun is similar in size and density to Earth, with it being only 638 kilometres (396 miles) smaller in diameter and 0.27 grams per cubic centimetre lower in density. These physical dimensions may paint a picture of a world similar to Earth, but that is far from the case. The truth is Venus underwent a different evolution, and its completely different atmosphere has fashioned the hottest surface temperature in the entire
Solar System at 465 degrees Celsius (869 degrees Fahrenheit), with atmospheric pressures that are over 90-times that of Earth at sea level.
Venus’ atmosphere is composed mainly of the greenhouse gas carbon dioxide, with small amounts of nitrogen and traces of other gases, most notably sulphur dioxide and argon. Comparing this atmosphere to Mars – which is about 100 times thinner than Earth's – again shows that their evolutions took opposite approaches in the sense that one planet lost its atmospheric greenhouse gases, while the other formed a thick atmosphere and, as a result, traps heat in a ‘runaway greenhouse effect’. In between these planets – both literally and scientifically – is Earth, as it has moderate amounts of greenhouse gases that allow it to trap enough heat to maintain a habitable surface temperature, perfect for the existence of life.
Looking at the surface of Venus has revealed some extremely interesting characteristics that help astronomers and planetary scientists understand the planet’s true interior. For instance, volcanoes have been observed on Venus, such as the Idunn Mons volcano in the planet’s southern hemisphere rising 2.5 kilometres (1.6 miles) above the surrounding plains. This volcanism is a sign that there is active mantle underneath the rocky surface. This would explain what is powering these volcanoes and also what is replenishing the sulphur dioxide in the atmosphere, creating the acidic clouds too. It has also been theorised that Earth-like thunderstorms occur and sulphuric acid rain peppers Venus’ surface, originating from these clouds. Although volcanoes indicate that the planet’s surface can be smoothed over by running lava, making it appear younger, there have still been many impact craters spotted on the surface.
Scientists have theoretically scratched the surface and revealed that the interior of Venus is thought to be composed of a partially liquid metallic core and a rocky mantle above that.
This theory is based on the calculated mass and density, suggesting the planet is made up mainly of rocks and metals. This remains a theory for now due to observations being much harder because of the planet’s thick atmosphere.
Venus hasn’t had the same degree of surface visits and orbiter attention as Earth’s neighbour on the other side, Mars, due to its lead-melting surface temperature and toxic acid clouds, but it has still been visited by several spacecraft. It has also been influential in providing a ‘gravitational slingshot’ to missions such as the Cassini-Huygens, MESSENGER and Galileo that took their respective spacecraft to Saturn, Mercury and Jupiter.