Why is the planet Venus so Hot?

The planet Venus
The planet Venus (Source: NASA)

Can you imagine a temperature at which lead melts? Venus is the planet where such a high temperature exists. Although Venus is not the nearest planet to the sun but still it is the hottest planet in our solar system, hot enough to destroy any space probes in very little time. The temperature of Venus is around 471 degree Celsius whereas the temperature of Mercury is 466 degree Celsius in the day, in spite of being the nearest planet to the sun.

The temperature of Venus remains same whether it is day or night, equator or poles. Venus is called the sister planet of Earth but still there is a huge difference in the environment of these two planets.

The question arises why is the temperature of Venus is so high?

Atmosphere of Venus
The thick blanket of the atmosphere around the planet Venus. (Source: NASA)

The answer somewhere lies in its thick blanket, its ‘atmosphere’. The atmosphere is very different from Earth. It is composed of 97% carbon dioxide, 2% Nitrogen and less than 1% of oxygen, water, and methane. There is also a substantial amount of sulphuric acid in the lower atmosphere which forms clouds and causes a rain of sulphuric acid.Thunders and lightning also exist on Venus which is related to sulphuric acid clouds unlike water clouds on Earth. The atmosphere is so thick that its pressure is 90 times the atmospheric pressure on Earth. This atmospheric pressure can press you as hard as water 3000 feet beneath Earth’s Oceans.

Now after knowing about the atmospheric status of Venus, you will be thinking that how can atmosphere heat up Venus to such a high temperature? But you are missing 97% carbon dioxide and sulphuric acid, both are good Greenhouse Gases. So let us look at it more carefully. The Greenhouse Gases will allow the sunlight to enter into the atmosphere of Venus but will not allow them to go out into space. In this process, heat starts accumulating on the Venus and give rise to high temperature.

The atmosphere of Venus has very high reflectivity, that’s why it reflects most of light of the sun and make Venus brightest object in the sky. Due to its high reflectivity, the surface of Venus is not visible to us. NASA’s Magellan mission to Venus during the early 1990s used radar to image 98 % of the surface, and the Galileo spacecraft used infrared mapping to view mid-level cloud structure as it passed by Venus in 1990 on its way to Jupiter. In spite of thick atmosphere, cyclones of high speed up to 360 km/h exist on Venus, the reason of this is still not clear to the scientist.

The surface Venus is also much different than the surface of Earth. Craters which are smaller than 1.5 to 2 Km do not exist on Venus because small meteors burn up in the dense atmosphere before reaching the surface. It is believed that Venus was completely resurfaced by volcanic activity 300 to 500 million years ago. More than 1000 volcanoes larger than 20 Km in diameter are still present on the surface.

We can see that the Venus is not the place where any life form can survive. Still, it is one of the amazing planets of our solar system.






5 thoughts on “Why is the planet Venus so Hot?”

  1. Venus may be the second planet coming from OUR Star, the Sun, along with the planet nearest to be able to Earth. obtaining the rocky composition similar to MY OWN own planet, Venus is actually likewise almost ones same size–and your current obvious similarities between what turned out to help always be only two very some other worlds, caused a few previously astronomers for you to designate Venus Just as "Earth's twin. http://www.mordocrosswords.com/2015/12/nearest-planet-to-sun.html

  2. I still don’t get “why Venus is SO hot.” Semantics are important. CO2 does not TRAP heat. It slows down cooling. On earth with 400ppm CO2 and a less massive atmsophere IR from the surface is extinquished in 25m or so, and then reemitted, ~half going (and half going down) only to be again extinguished again in SLIGHTLY more than 25m (because the atmosphere gets less dense with altitude. And so on up the ladder until the atmosphere is so thin that the last reemissions up escape to outer space. Indeed, Energy in – reflected energy = energy out on Earth (ignoring heat sinks, like the oceans. So on Venus this same process happens and given the 92 bar atmosphere at the surface I imagine it just takes a few inches (if that) for the typical CO2 IR to be entinguished, but it’s essentially the same story — GHGs slow down the cooling of Venus — they don’t “Add energy.”

    Then there’s the logrithmic nature of CO2’s effect. On earth every doubling adds the same 3.71W/M2 of forcing (at least up to about 1000 ppm). I realize that with pressure there should be broadening of the “wings” of CO2’s IR resonance bands and that there will be more like 3 effective bands on Venus rather than only the 15micron band on Earth (because there’s no water vapor on Venus which on Earth moots the other 2 CO2 resonance bands). But still…. 16,000W/M2 on the surface??!!!

    Of course it is what it is and I suppose I should leave it at that. But I’m wondering: If you had a sufficiently long enough pipe, perfectly insulated, filled with CO2 and you shined a 1 watt light through one end, would a solid steel plug at the other end be melted away?

  3. Elaborating on my previous comment….

    Venus has 221,950 times the Co2 as earth (96.5%/400ppm x 92 bar = 221,950)

    It woud take 17.8 doublings of our current CO2 to equate to 228,210 …. close enough (2 raised to the 17.8th power = 228,210)

    On earth, each doubling adds 1.1C, which only gets you to 20C for 17.8 doublings. Yet Venus is over 450C hotter than earth. Why?

  4. The answer is very simple pressure. Nothing to do with co2. If you compress any non- greenhouse gas the result is the same. Just look at your fridge from behind and feel the heat from the compressor.
    If you don,t believe it. Ask yourself why Jupiter is hot despite being so far away from the sun. Pressure again.
    When you have people doggedly seeing co2 as the villain the blinkers are on and simple questions like this cannot be answered.

    1. You are 100% correct. Consider Mars, also with a 96% CO2 atmosphere and a similar SW flux to Venus. And yet it is a frosty -63 degrees Centigrade, with an atmospheric pressure only about 1/1000 that of Venus.

Leave a Reply

Your email address will not be published. Required fields are marked *