To say that the surface of Venus is warm would be quite an understatement. At 471 degrees Celsius (over 880 degrees Fahrenheit) on average, Venus takes the honors of being the hottest planet in the solar system. This is hot enough to melt lead, so vacation getaways to this world in some distant future can pretty much be ruled out. Perhaps the most interesting fact is that it is no cooler at the poles or at night. Instead, it stays at a constant temperature all the time and at every location.
So what is the reason for this? Why is Venus such a hellish, inhabitable place?
This planet has what is known as a runaway greenhouse effect. While Venus and Earth are similar in size, mass, gravity, and even internal composition, there is one major thing that sets these so-called “sister” worlds apart. Venus has a much thicker atmosphere. In fact, the atmospheric pressure of Venus is around 93 times that of Earth. To put this into perspective, you’d have to be situated about one kilometer beneath the ocean’s surface to feel such pressure at home on Earth.
Another major factor for the hot temperatures on Venus is that this planet’s atmosphere is made up mostly of carbon dioxide, and it just so happens that carbon dioxide serves as an excellent source for trapping heat from the sun. Gases that allow such absorption are called greenhouse gases.
Venus also has a thick and heavy cloud cover over the surface. Sunlight still manages to pass through the clouds and heat the rocks, volcanoes, and deformed, literally melted mountains on the planet’s surface. In turn, the infrared heat from the surface is trapped and prevented from escaping by the thick clouds. Think of a dark, overcast sky here on Earth just before a summer thunderstorm. The temperature warms up in the same manner because the clouds above trap the radiant heat from the ground.
In the case of Venus, the clouds are composed mostly of sulfuric acid, which reflect sunlight as it enters the atmosphere. Paired with the fact that Venus is about 30% closer to the sun than Earth, this also helps explain the extremely hot temperatures. Because of this reflected sunlight and its close distance to Earth, Venus will also appear to be very bright in the sky. As viewed by the naked eye, Venus is oftentimes referred to as either a morning or evening “star.” However, if one knows exactly where to look, Venus can sometimes even be seen in broad daylight.