What is the Hottest Planet?

Mercury, the closest planet to the Sun, isn’t the hottest planet in our solar system. Instead, Venus, the second rock from the Sun, is the hottest planet. Even though Venus is close to Earth’s twin in size and density, its temperature and liveability drastically differ. The worlds couldn’t be more different!

Venus: The Hottest Planet

This planet, named for the love goddess Venus and the only world with a female name, is anything but lovely. Venus’s atmosphere is so thick that walking on it would feel like wading through hip-deep water. That is, if you could walk on Venus without immediately bursting into flames from the heat. Even though it’s closer to the Sun than Earth, the thick atmosphere on Venus makes the Sun’s light very dim.

Hottest Planet
Image Credit: NASA/JPL-Caltech from Mariner 10 spacecraft

Missions to Venus: Exploring the Hottest Planet

The hottest planet is also one of the most studied planets in the universe. Here are some Venus missions and flybys. 

NASA’s Mariner 2

In the image below, scientists display Mariner 2’s flyby data from the 1962 mission to the hottest planet in the universe. The data found no real difference in Venus’ surface temperature from the dark side to the dayside. Instead, it recorded findings with a moderate change from 421℉ (216℃) to 459℉ (237℃.) Scientists now know the average surface temperature is closer to 847℉.

JPL Project Manager said, “There will be other missions to Venus, but there will never be another first mission to Venus.”

Mariner 2
Image Credit: NASA/JPL-Caltech

NASA’s Magellan

NASA’s Magellan mission to Venus lasted from May 4, 1989, to October 13, 1994. Magellan was launched by the space shuttle Atlantis before imaging Venus’ entire surface. Both accomplishments were NASA’s “firsts.”

NASA’s Pioneer Venus Multiprobes

Pioneer Venus 1 & 2 cone-shaped probes collected data when entering Venus’ atmosphere in 1978. While scientists didn’t expect them to survive the surface impact, two of the small probes did. One transmitted surface data for 67 minutes and 37 seconds before burning up.

ESA’s Venus Express

From the 2005 launch until 2014, the European Space Agency’s (ESA) Venus Express orbited Venus. The spacecraft studied (in great detail) the interactions between Venus’ atmosphere and surface, as well as those between the atmosphere and the solar winds. 

The German-based mission launched from Soyuz-Fregat/Baikonur, Kazakhstan, on November 5, 2005, and studied Venus until fuel exhaustion on Dec 16, 2014.

Venus Climate Orbiter Akatsuki

Japanese explorer, Venus Climate Orbiter Akatsuki, launched on May 21, 2010, with five cameras to document the journey. The infrared, visible spectrum and ultraviolet cameras will photograph Venus’ atmosphere. Another mission component investigates volcanic activity and solar lightning.

Parker Solar Probe

NASA’s solar probe, Parker, captured its first visible light images of Venus’ surface in a February 2021 flyby during its mission to touch the Sun. Below is one of the nightside surface images. 

Parker Solar Probe
Image Credit: NASA/APL/NRL

The Hottest Planet’s Details: 10 Venus Facts

Here are some fun facts about the hottest planet, Venus.

1. Short Years but Long Days

One Venus day takes 243 Earth days because the hottest planet rotates so slowly on its axis. However, Venus makes its trip around the Sun faster than Earth in only 225 Earth days. It’s hard to imagine, but one Venusian year is shorter than its day!

2. Second Rock From the Sun

Venus orbits the Sun at a distance of 67 million miles (108 million kilometers.) That’s close, considering Earth orbits at a distance of 93 million miles (146 million kilometers.)

3. Volcanic Plains

Venus is a terrestrial planet with massive volcanic plains, mountains, and vast crater fields. The rusty-colored mountainous surface has thousands of giant volcanoes, some of which still show signs of activity.

The image below comes from the Magellan mission and captures “The Crater Farm.”

Volcanic Plains
Image Credit: NASA/JPL

4. Youthful Appearance

It’s almost as if the hottest planet gave itself a facial! Estimates of the surface age placed by planetary scientists place it between 150 million and one billion years. That’s very young, considering the universe is around 4.6 billion years old. Scientists still need to figure out why Venus has such a young surface and youthful appearance.

5. Similar to Earth’s Core

You could see their similarity if you sliced Venus and Earth in half like boiled eggs:

  • Both planets have iron cores.
  • There is a hot-rock mantle. 
  • Each planet has a thin rocky crust.
  • Both worlds experience changes to the crust with volcanic eruptions responding to heat and pressure from within. 

6. Toxic or Evil Twin

Venus and Earth are twins in size and structure, and once upon a time, they might have shared similar climates. But today’s Venus has a dense carbon dioxide atmosphere. Its surface pressure is similar to being a mile underwater here on Earth. 

The average surface temperature on Venus stays around 900℉ (475℃), so it’s hot enough to melt lead. The hottest planet is definitely a toxic twin to Earth.

Image Credit: NASA/JPL Computer Simulation of Venus’s Northern Hemisphere

7. Rotten Eggs

In addition to its carbon dioxide atmosphere, Venus stinks. It has a rotten egg smell because of its permanent, toxic sulfur and sulfuric acid clouds. This thick layer of toxicity starts around 28 miles of altitude and ranges up to 43 miles (45-70 kilometers.)

8. Runaway Greenhouse

Venus’s thick carbon dioxide atmosphere traps the Sun’s heat, while the toxic sulfuric acid clouds act like a blanket. The combination creates a “runaway greenhouse effect,” making Venus the hottest planet. 

9. Backward Rotation

Compared to the other seven planets in the solar system, Venus rotates backward on its axis. The Sun rises in the west and sets in the east, which makes it Earth’s backward twin. 

Beyond the planets, most other solar system objects rotate counter-clockwise. That rotation includes the Sun and asteroids. Scientists attribute this “backward direction” to the clouds of dust and gas that collapsed and spun as the solar system formed. 

Venus likely was struck by a planet-sized object during the chaos of formation, which threw it into a clockwise spin.

10. Is Life on Venus Possible?

Venus visitors (humans) would die instantaneously. Here are some likely scenarios.

  • Scorching heat burns you to a crisp.
  • Your body gets dissolved by sulfuric acid.
  • The dense air pressure crushes you.
  • The atmosphere is suffocating.

Life as we know it is highly improbable on the universe’s hottest planet. One positive sign, however, is the observed presence of Phosphine in the clouds. The cloud conditions about thirty miles up might accommodate some Earthly inhabitants, such as “extremophile” microbes. Temperatures up there range from 86 to 158℉ (30 to 70℃) with a lower atmosphere closer to that of Earth.

Final Thoughts on What is the Hottest Planet

The hottest planet turns out not to be the closest planet to the Sun, but instead, the second rock from the Sun. Venus is a fiery scorching rock ball with an intensely hot surface that melts lead. Even though Venus is the only planet named after a female goddess, this planet spews anything but love. Inhospitable to life as we know it, the hottest planet scorches everything in its path.