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Why isn’t Mercury the Hottest Planet?

If any planet in our Solar System were going to be the hottest, you would have to think it would be Mercury.


It is the closest to the sun, and its name is synonymous with temperature because of the metal of the same name which used to be in thermometers. However, this is not the case.

In this article, you’ll find some quick facts about Mercury, as well as an explanation as to why it isn’t the hottest planet.

We will also reveal which planet is the hottest planet, and why!


The Planet Mercury: Some Quick Facts

Here are some quick and interesting facts concerning Mercury.

Mercury is the closest planet to the sun.

As such, it takes the least amount of time to orbit the sun of any of the planets in the Solar System. One year on Mercury is only 88 days on Earth.

sun and planets

While a year on Mercury passes by pretty quickly about Earth, a day on Mercury is a different story. It takes the planet 176 Earth days to rotate once on its axis.

Due to its speedy orbit, it was named by the Romans after their god Mercury, who was the swiftest of all the gods.

Mercury is the smallest of all the planets and only has about 38 % the gravity of Earth. That means that if you weigh 200 pounds on Earth, you’d only be 56 pounds on Mercury!

So why isn’t Mercury the hottest planet?

Though it would seem to make sense that Mercury is the hottest of all of the planets in our Solar System, this is simply not the case.


Since Mercury lacks an atmosphere, it has no way of trapping the heat that is generated by the sun, thus leading it to have periods of both hot and cold.

Though it isn’t the hottest planet, it is still comes in a respectable second place, even without an atmosphere.


Which Planet is the Hottest?

The hottest planet in the Solar System is none other than the second planet from the sun, Venus.

While it is further away from the sun than Mercury, it has a dense atmosphere which traps the heat from the sun.

This raises the overall sustained temperature on its surface above the levels found on Mercury.


Final Verdict: Definitely the Fastest, Just not the Hottest!

And there it is! While Mercury might not be the hottest planet due to its lack of any sort of atmospheric assistance that Venus enjoys, it is still the fastest planet.

It’s also the smallest planet, as well. Now, why not find out more about our amazing universe?

Planets & Science

planets grouped together