Venus is the second planet from the sun, but it is the hottest planet in the solar system! That’s right - it’s hotter than Mercury! This is because Venus has a thick cloud layer in its atmosphere, made up of carbon dioxide.
Billions of years ago, Venus was probably very similar to Earth, and may have had liquid water on its surface. When sunlight shines on Venus, it bounces off the planet. Greenhouse gases in Venus’ atmosphere such as carbon dioxide and nitrogen absorbed this radiation coming from Venus, and then radiated it back towards the surface of the planet. The heat then could not escape, because the atmosphere was so thick!
Eventually, most of the water on Venus evaporated, and the thick atmosphere slowly trapped more and more heat close to the planet. This is why Venus is the hottest planet in the solar system. This also creates very high pressure on Venus - to experience this pressure here on Earth, you would have to go 1km below Earth’s surface!
The average temperature on the surface of Venus is 864 degrees fahrenheit (462 degrees celsius). In the very upper atmosphere of Venus, temperatures are much cooler - they can be as low as minus 173 degrees celsius. It is a rocky planet, with many craters and volcanoes.
Figure 1: Visible as the bright patch below central North is Venus' highest mountain Maxwell Montes. Other notable features include numerous mountains, coronas, impact craters, tessera, ridges, and lava flows. Image credit: SSV, MIPL, Magellan Team, NASA.
Venus takes a long time to spin once on its axis (243 Earth days), and its day takes longer than its year. This means that temperatures on Venus remain relatively consistent, and the nights are not significantly cooler than the days.
The axial tilt of Venus is also very slight (just over 3 degrees). The axial tilt of a planet is what creates its seasons: we have four seasons here on Earth, while Uranus has such an extreme tilt that it is in darkness for half the year, and light for the other half. The very slight axial tilt of Venus means that there is very little variation throughout the year - instead, temperatures and weather patterns remain consistent year-round.
Venus is around the same size as Earth, but it is far too hot to support any forms of life that we know of. It may be close to being Earth’s twin in terms of size, but it’s easy to see that it is very different in a number of major ways!