Planet Profile

Earth’s sister planet is a harsh, deadly world, making it an interesting one to observe

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’s far from the case. Venus underwent a different evolution, and its dense 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’s 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 highlights that these planetary evolutions took opposite approaches; 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. It has moderate amounts of greenhouse gases that allow it to trap enough heat to maintain a habitable surface emperature that’s 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 Idunn Mons 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. It’s also been theorised that Earthlike thunderstorms occur and sulphuric acid rain peppers Venus’ surface, originating from the acidic 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.