Why Is Venus The Hottest Planet In The Solar System?

Venus is the second planet from the Sun, after Mercury, and the closest planet to us on Earth. Not only is Venus the closest to us, but it is the most similar in size and mass, and is often referred to as Earth’s twin! 

Although spaceships have travelled to and around Venus, none have actually landed on the planet due to its extremely high temperatures.

When spacecraft travel to Venus, they do not last long, as the Venusian temperature quickly overheats the electronics, which means no human has ever stepped foot on Venus. 

Why Is Venus The Hottest Planet In The Solar System

As Venus is the second closest planet to the Sun, and Mercury is the closest, you may be led to believe that Mercury is the hottest planet in the Solar System, however this is untrue.

Venus is actually the hottest planet, with surface temperatures hot enough to even melt lead. So why is Venus the hottest planet? Let’s take a closer look.

Why is Venus So Hot?

Venus is actually the hottest planet because of its extremely thick atmosphere. The atmosphere on Venus is actually about 100 times larger than the atmosphere on planet Earth.

This atmosphere works to trap heat and gases, in a sort of greenhouse effect, where no heat can escape. 

Venus is so hot as its atmosphere is full of greenhouse gas, carbon dioxide, and has clouds made of sulfuric acid.

Its thick atmosphere leaves no room for these to escape, and becomes trapped in the atmosphere building up to extremely high temperatures so that they simply heat up the planet instead. 

In addition, Venus is a lot closer to the Sun than planet Earth is. Venus lies just 108.93 million kilometers away from the Sun, which is actually 30% closer to the Sun than Earth is. Mercury is only 59.187 million kilometers from the Sun, and yet, Venus is hotter.

This is mostly down to its atmosphere, but there are other contributing factors that make Venus so hot. As a planet, Venus has active volcanoes and toxic, sulfur fumes in abundance. In its structure, Venus is quite similar to planet Earth. 

Venus has an iron core close to 2,000 miles in radius, and above that is a mantle made of hot rock that is always slowly churning because of Venus’ interior heat. Venus also has a thin crust of rock on the surface that can move as the planet’s mantle shifts, creating lots of volcanoes.

Venus actually has tens of thousands of volcanoes across the planet, with large mountains and a dusty surface.

Its hot temperatures make it a hostile planet, with no signs of life, and scalding hot surface temperatures so extreme, that even the strongest of metals would simply melt into a puddle if they should come into contact with it.

How Hot Is Venus?

Venus is so hot due to its atmosphere. The average temperature of the Venusian atmosphere stays around roughly 863-870 degrees fahrenheit, or 462-465 degrees celsius.

Venus’ atmosphere is so thick, that it works as a blanket around the planet, where no heat can escape back into space. 

In addition, the planet’s atmosphere is so highly reflective that it absorbs only 2.5% of solar energy, whereas Earth will absorb around 50%.

This, combined with its blanket atmosphere means that there is very little variation or change in Venusian temperatures, and they remain consistent throughout days, nights and across the planet. 

Why Isn’t Mercury The Hottest Planet In The Solar System?

Mercury is around 58 million kilometers from the Sun. Seeing as Mercury is actually much closer to the Sun than Venus, it would make sense for the planet to be the hottest, yet Venus knocks it out of the park, with a temperature of 870 degrees fahrenheit. 

The reason for this is simply Venus’ incredibly thick, CO2-packed atmosphere that works to stop any heat escaping, which maintains its heat at a consistent, high temperature.

Do not be fooled, Mercury is also very hot at around 800 degrees fahrenheit, Venus just has that boiling hot edge, making Venus the hottest planet in the Solar System. 

Venus is often called the brightest object in the sky, after the Sun and the Moon. Its astoundingly bright appearance is mainly due to its reflective surface, that makes it look as if it is shining bright like a diamond when it reflects the sun.

When planets receive sunlight, they will typically absorb some of it, and they reflect the rest back into space. This process is called albedo.

Every planet has a different albedo, or rate of absorption. Each planet's albedo will be affected by the amount of sunlight they absorb, and the reflectiveness of the planet. 

In general terms, the lower the rate of absorption, then the higher the albedo. When we look at Mercury’s albedo, it is about 0.119, which shows us that around 11.9% of sunlight is getting reflected, whilst 88.1% is being absorbed by the planet.

In comparison, Venus’ albedo is 0.9, which means around 90% of sunlight is reflected by the planet. 

This is why Venus is often considered the brightest planet, and is so easy to locate with our telescopes! 

Venus is so much hotter than Mercury because when it receives sunlight, it keeps the heat it gains in its powerful atmosphere, whereas Mercury cannot.

Mercury’s thin atmosphere is built up of hydrogen, oxygen, helium and potassium, which blow upwards from its surface, which means a lot of Mercury’s sunlight is sent back into space. 

In contrast, Venus’ thick atmosphere consists of carbon dioxide and nitrogen, which is so much denser and hotter, and works to trap all of the heat inside the atmosphere of the planet, heating up the surface!

In addition, Mercury will absorb its heat throughout the day, and dissipate the majority of it at night, whereas Venus maintains its heat consistently. Its insulating nature means that the temperature never really drops or changes, making it much hotter than Mercury.

Where Did Venus’ Atmosphere Come From?

The atmosphere around Venus has come from the planet's development. During Venus’ evolution, lighter gases were blown away by powerful solar winds, leaving carbon dioxide and nitrogen behind to dominate the makeup of the atmosphere.

Like all the other planets Venus did have lighter elements such as hydrogen and helium, however these quickly evaporated overtime.

Leaving behind carbon dioxide, this gas makes up the majority of the Venusian atmosphere, and created the greenhouse effect, heating up the planet to unimaginable temperatures.

What Is The Venusian Atmosphere Made Of?

As previously stated, the Venusian atmosphere is so hot due to its most abundant gas being carbon dioxide, or CO2. This gas accounts for around 96.5% of the Venusian atmosphere, whereas nitrogen makes up the other 3.5%.

In addition, there are also small traces of carbon monoxide, argon, neon and sulfur dioxide within the blazing hot Venusian atmosphere.

What Is The Climate Like On Venus?

In general terms, you may have guessed that Venus is a hot and dry planet. Its surface is not actually visible from the outside due to its thick blanket-like atmosphere, yet the surface is supposedly dry and dusty.

In addition, around 60% of Venus is actually covered by flat, smooth plains dotted with thousands of active volcanoes, and the temperature on the surface is thick and heavy.

The wind on Venus can reach speeds of up to 190 miles per hour or 300kph, yet the winds at the surface are almost nonexistent due to the high air temperature there.

The winds actually work to move heat up and around the planet at all times, whilst the atmosphere works to prevent any heat from dissipating into space.

There is also no water in the Venusian atmosphere. As a planet, Venus does not experience precipitation or storms due to its dense atmosphere, however its sulfuric acid clouds can produce some lightning!

As Venus does not have an axial tilt, the planet does not actually experience seasons like planet Earth. As Venus does not have a tilt, its two hemispheres do not have different amounts of sunlight throughout the year, which means the planet gets no seasons. 

Venus’ lack of a tilt is also the reason the planet’s orbit as pretty much circular, which tells us that the planet receives the same amount of light from the Sun and stays at a similar distance all year around. This is another reason that the hot temperatures do not fluctuate on Venus!

The climate of Venus has little or no potential for life, which is why humans have not explored the planet. As this is the case, you may be asking how do we study Venus?

How Do We Study Venus? 

With such a hostile, hot and inhospitable environment, you may be wondering how we have the data and information to understand Venus as a planet.

As we said, spaceships would begin to malfunction when they get too close to its boiling surface, and so you may be wondering how do we know all of this? 

As the planet is very inhospitable, it seems unimaginable for humans to ever explore Venus. However, we have succeeded in gaining valuable information from missions into space.

This is done by using spacecrafts to fly to the surface, whilst transmitting images and information about the planet in a fast manner, before the high temperatures destroy the equipment and ruin the spacecraft.

The first mission to Venus was the Mariner 2 in 1962. This spacecraft managed to fly by the planet and scan its cloud covered surface on December 14th of the same year. 

On December 15th, 1970, the Venera 7 was the first spacecraft to actually make a soft landing on Venus.

The spacecraft was able to transmit information for about 23 minutes whilst on the surface, before succumbing to the immense heat and pressure. In the following years, Venera 9 would succeed in sending the first images back to Earth from the surface of Venus!

In 1981, the Venera 13 spacecraft actually managed to make it through the hot layers of Venus’ atmosphere and landed on the surface.

Surviving for just 127 minutes, the spacecraft managed to send color photographs, measurements and data back to Earth before the Venera 13 melted entirely. 

Following this, in 1990, a US spacecraft called Magellan utilized radars to map out the surface of Venus, giving us valuable information on the surface, texture, and details of the planet’s structure.

Currently, a Japanese space mission called Akatsuki is studying the planet’s atmosphere for further information. 

Whilst scientists may continue to explore planet Venus, it seems highly unlikely that humans will ever be able to walk the surface of the hottest planet in the Solar System.

Andy Morgan

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