What’s The Hottest Planet In Our Solar System? [Not The Sun]


Have you ever wondered which planets are the hottest? Scientists have been exploring and gathering data on other planets as well over the past several decades to understand them better.

But do we know for sure which is the hottest planet in the solar system and how hot it is? What makes it so hot and how are the other planets when compared to it?

Keep reading to find answers to all your questions and more! We will also be diving deeper into how scientists calculate the heat of planets and what they mean. You would be amazed to know how diverse our solar system is.

Which Planet Is The Hottest?

After people realized the Earth wasn’t the hottest in the solar system, they studied each planet. People thought Mercury would be the hottest, as it is closest to the Sun.

But surprisingly, it is Venus that is hottest owing to its temperature of 869 degrees Fahrenheit! This is due to the dense clouds that envelop this planet along with the unique composition of its atmosphere.

Venus has incredible heat retention and most of the heat generated is stored within its atmosphere. The clouds surrounding it contribute to this effect greatly. Why does Venus have such a hot surface when even Mercury isn’t so hot?

The Secret Behind The Heat Retention

Did you know that Venus was the first explored planet in our solar system? It is quite clearly visible from the Earth and exhibits phases like the Moon. These phases can be observed from the Earth using a basic telescope.

The high temperatures witnessed on Venus are owing to the greenhouse effect covering the entire planet. The planet can retain almost 96% carbon dioxide and close to 3.4% molecular nitrogen.

What's The Hottest Planet In Our Solar System? [Not The Sun]

It can trap the Sun’s heat faster than all the other planets and retains it internally for a longer duration. Can you believe that the temperature on Venus is high enough to even melt lead?

Is Venus Toxic?

Despite being the hottest planet in the solar system, Venus is also one of the most toxic. Owing to the dense clouds and atmospheric layers surrounding Venus, the planet is almost 90 times denser when compared to Earth.

People wouldn’t last a moment on Venus as the atmosphere consists of carbon dioxide and sulfuric acid-laden clouds. This makes the planet very toxic and completely impossible to inhabit.

In 2020, scientists found a chemical called phosphine in the clouds on Venus, which is produced by microbes on Earth. This makes the gases and clouds on Venus extremely poisonous and breathing is difficult on its surface.

How Long Are The Days On Venus?

Ever noticed how the days on Earth seem to stretch longer when it is hot? If summer days can be so long, imagine how much longer days on Venus would be!

The usual days on Venus are very long and each day is equivalent to 243 days on Earth. This is more than half a year long! This is due to half of the planet’s surface being exposed to solar radiation that is more intense than the other half.

The nights on Venus are known to be as hot as the days owing to the heat retention we have already discussed. The yellowish clouds laden with poisonous gases add to the effect of long days and nights.

Can Venus Get Any More Unique?

Yes, it can! Let’s begin with how Venus spins in the opposite direction to all the other planets in the solar system. Venus rotates clockwise on its axis and this phenomenon is suspected to be the result of solar tides acting on its atmosphere.

It could also be due to the collisions with large bodies in the past. There are also questions about Venus’s heat playing a part in its rotation. However, these are mere speculations and the true reason behind Venus’s strange behavior is unknown.

It is also worth noting that Uranus spins in a sideways direction. Venus’s upper atmosphere spins faster than any other planet and whips around the planet once every 4 days. This is called a superrotation that occurs due to thermal tides by the Sun.

How Do Scientists Measure And Calculate A Planet’s Temperature?

Be informed that these deductions are not made based on current facts. They are the results of decades of research and analysis. With the help of robotic space probes, scientists have been exploring the solar system since the 1950s!

It is also interesting to note that none of the initial robots sent to Venus lasted more than two hours. This undoubtedly is due to the intense heat on Venus and the unbearable atmosphere.


Most of the space probes sent to Venus today have been designed to measure heat and light from a great distance away. When it comes to measuring the details of the other planets, the space probes are equipped with infrared sensors.

Finally, based on how far the planet is from the Sun, the readings are measured and compared. The space probes sent to the other planets travel as close to the planet as possible to gain accurate readings. Some of the other factors they keep in mind are:

  • The composition of the planet’s atmosphere.
  • The planet’s size and shape.
  • The planet’s orbit and direction of rotation (in some cases).
  • How do the elements of the planet interact with heat?

How Is Venus Similar To The Earth?

Venus is popularly known by scientists and referred to as the Earth’s twin. The two planets are similar in size and have similar structures as well. The Earth isn’t as hot as Venus, but we can observe the clouds and shadows on Venus with our naked eyes.

Venus is different from the Earth in terms of the direction it spins and how long its days last. One day on Venus would be almost 243 days on Earth and the atmosphere on Venus makes it difficult for people to survive on it.

The air pressure on Venus is over 90 times that of the Earth. To give you an idea about how much this is, imagine the pressure you would feel if you were a mile below the ocean’s surface. This is how dense the planet is and how crushing it would feel on it.

Why Isn’t Mercury As Hot As Venus?

It is time to face the first question we encountered. Despite being the closest to the Sun, why isn’t Mercury the hottest planet in the solar system?

The most obvious reason would be due to the differences in the atmosphere as observed on both planets. Mercury does face intense solar radiation that is more severe than all the other planets.

Due to its proximity to the Sun, Mercury reaches close to 800 degrees Fahrenheit on one side regularly. This side of Mercury is hotter than Venus for most of the year. The other half isn’t as exposed to the Sun and is much colder.

Mercury lacks an atmosphere despite being surrounded by a gaseous layer. It is very thin and has an exosphere that covers the planet’s outermost layer. This layer has many gases, including:

  • Oxygen
  • Hydrogen
  • Helium
  • Sodium
  • Potassium

This makes it a poor conductor of heat, and needless to say, the other side of the planet that doesn’t face the Sun is worse. It could reach a coldness of close to -292 degrees Fahrenheit and remain in that state regularly.

Frequently Asked Questions

  1. Is Mercury The Hottest Planet As Recorded By Scientists?

No, despite being closest to the Sun, Mercury is not the hottest planet. It is Venus owing to its greenhouse effect and extremely dense atmosphere. This makes it the hottest planet with a poisonous atmosphere.

  1. Why Is Venus The Hottest Planet Despite Being So Similar To The Earth?

Venus is similar to our Earth in many ways. But it is different in terms of its direction of rotation and atmosphere. The gases and clouds on Venus make it very dense and help it retain a lot of heat. This makes it very hot and toxic.

  1. Is Life Possible On Venus?

Although scientists haven’t yet confirmed it, there does seem to be life on Venus and a chance of civilization if we can get past the toxicity. The atmosphere is filled with poisonous gases which we cannot survive in.

Summing Up

It is now clear that Venus is the hottest planet in the solar system and can retain more heat than even Mercury. It is filled with poisonous gases that make it very toxic and not suitable to inhabit.

It is also known to spin in a different direction as compared to the other planets and can spin faster than all the other planets. With the knowledge we possess, it is possible to imagine life on Venus once we overcome the heat and gases.

Even space probes sent to Venus couldn’t withstand the heat, which puts a big question mark on human life. But with evolving technology and advancement in knowledge, we could find life on the planet.

Guess we were wrong when we thought women are from Venus. Even they couldn’t stand the dense clouds and hot atmosphere!

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