Which Planet is the Hottest?

Quck answer

The hottest planet in our solar system is Venus. It has an average surface temperature of about 900 degrees Fahrenheit (475 degrees Celsius), which is hotter than Mercury, the closest planet to the Sun. Venus has a thick atmosphere composed mainly of carbon dioxide, which creates a greenhouse effect, trapping heat and making it the hottest planet. Despite being further away from the Sun, Venus experiences a stronger greenhouse effect than any other planet, causing its extreme temperatures. The high temperatures on Venus make it inhospitable for life as we know it.

Recall the middle of August when you finished mowing the lawn. The sun was scorching and it felt like it must have been at least 110 ºF outside. You thought it was probably hot enough to fry an egg on the sidewalk.

It may have seemed like you were standing on the surface of the Sun. However, Earth—even on its hottest days—is much more bearable compared to the hottest planets in the solar system. Which planet holds the title for being the hottest?

The further you move away from the Sun, the cooler it gets. So let’s examine those planets that lie between Earth and the Sun: Mercury and Venus.

Since Mercury is the closest to the Sun, it would logically be the hottest planet. Right? That only makes sense, doesn’t it? After all, Mercury receives more sunlight per square foot than any other planet in the solar system. Wrong! Venus is actually the hottest planet in the solar system.

On a scorching day on Mercury, the temperature can soar to over 700 ºF. That’s extremely hot! You would definitely need plenty of sunscreen there. However, a hot day on Venus is even hotter. How much hotter? The highest temperatures on Venus surpass 900 ºF. Yikes! Now that’s a scorcher, without a doubt.

Most people are probably curious as to why Venus is hotter than Mercury. After all, it’s further away from the Sun. The answer lies in the atmosphere.

Mercury is small and is situated closest to the Sun. It also orbits the Sun very quickly. Due to these factors, it lacks an atmosphere. When the Sun’s rays reach Mercury, they simply bounce off into space. There is nothing to reflect them back towards the planet and retain their heat.

Venus, on the other hand, possesses a very dense atmosphere. In fact, its atmosphere is over 90 times denser than Earth’s atmosphere. It is also mainly composed of carbon dioxide, a greenhouse gas. Venus’s atmosphere acts as a one-way door. It allows solar radiation to enter, but it does not allow it to exit.

This creates conditions similar to an oven on the surface of Venus. Because of this intense heat, no water can be found there. Additionally, carbon dioxide is a toxic gas. It generates fierce winds that constantly blow across the planet’s surface. This gives Venus one of the harshest environments you are likely to encounter in the entire solar system. Earth and Venus are sometimes referred to as “sister” planets due to their similar sizes. However, in most other aspects, they couldn’t be more different.

Before scientists were able to observe Venus with the help of unmanned probes and space telescopes, many of them believed that Venus was a lush, tropical paradise. The reality is that it is a barren rock resembling Earth’s Moon. Its clouds appear yellowish due to the presence of sulfur dioxide along with the large amounts of carbon dioxide.

The knowledge that scientists now possess about Venus has been acquired from several unmanned probes sent to the planet over the years. The first spacecraft to land on Venus was a Soviet probe called Venera 7. It arrived on the planet in 1970. Unfortunately, Soviet astronomers only received data from the probe for about 23 minutes before the planet’s heat destroyed the probe’s electronics!

Is it possible that astronomers will send another probe to Venus in the future? The answer is uncertain. However, the potential knowledge that could be gained from studying Earth’s neighboring planet is intriguing. It is unknown what resources Venus might hold, but time will reveal the answers.

Give It a Try

Wow! Today’s incredibly hot Wonder of the Day has us perspiring. But don’t let the heat slow you down. Keep the learning experience alive by engaging in one or more of the following activities with a friend or family member:

  • Take a look at these images of Venus. What are your thoughts? Does Venus resemble Earth? Is it a destination you would like to explore? Explain your opinions to a friend or family member and find out what they think. Are they interested in visiting Venus?
  • Expand your knowledge about the planets in our solar system by referring to the information provided by NASA. Did you discover any fascinating new facts? Create a poster to educate others about the planets. Include at least one interesting fact about each planet. If you’re feeling artistic, try sketching your favorite planet on the poster too!
  • What other aspects of Venus would you like to learn about? Compile a list of questions that you have. Then, seek assistance from a friend or family member to find the answers. Begin your research by exploring online resources or visiting your local library. Enjoy the process of acquiring more knowledge about the second planet from the Sun!

Sources of Wonder

  • https://spaceplace.nasa.gov/all-about-venus/en/ (accessed 19 May 2020)
  • http://www.universetoday.com/36295/the-hottest-planet/ (accessed 19 May 2020)
  • http://www.universetoday.com/34534/is-mercury-the-hottest-planet/ (accessed 19 May 2020)
  • http://www.physlink.com/education/askexperts/ae425.cfm (accessed 19 May 2020)


1. What is the hottest planet in our solar system?

The hottest planet in our solar system is Venus. With an average surface temperature of about 900 degrees Fahrenheit (475 degrees Celsius), Venus is the hottest planet. This extreme heat is due to its thick atmosphere, which traps heat and creates a greenhouse effect. The high temperatures on Venus make it hotter than even Mercury, which is closer to the Sun.

2. How does Venus maintain such high temperatures?

Venus maintains its high temperatures primarily because of its thick atmosphere composed mainly of carbon dioxide. This atmosphere traps heat and prevents it from escaping into space, creating a greenhouse effect. The greenhouse effect is similar to what happens in a car parked in the sun, where the sunlight enters but cannot escape, resulting in a significant increase in temperature.

3. Why is Venus hotter than Mercury, even though Mercury is closer to the Sun?

Although Mercury is closer to the Sun, Venus is hotter because of its dense atmosphere. Venus has a thick layer of carbon dioxide gas in its atmosphere, which traps heat and creates a greenhouse effect. In contrast, Mercury has a thin atmosphere that cannot retain heat as effectively. Therefore, despite being closer to the Sun, Venus experiences higher temperatures than Mercury.

4. Are there any other factors contributing to Venus’ extreme heat?

Aside from its thick atmosphere, Venus’ slow rotation also contributes to its extreme heat. Venus rotates on its axis very slowly, taking about 243 Earth days to complete one rotation. This slow rotation causes the planet to have a weak atmosphere-to-surface temperature gradient, meaning that the temperature difference between the planet’s equator and poles is minimal. As a result, the heat is distributed more evenly across the planet, contributing to its overall high temperature.

5. How do scientists study the temperature on Venus?

Scientists study the temperature on Venus using various methods. They use spacecraft and probes to collect data, including measurements of the planet’s surface temperature, atmospheric temperature, and thermal emissions. Additionally, remote sensing instruments, such as infrared cameras and spectrometers, are used to observe and analyze the thermal radiation emitted by Venus. These observations and data help scientists understand the extreme heat on Venus and its impact on the planet’s environment.

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