How hot is the surface of Mercury?

The planet Mercury is so close to the Sun that you’d assume it’s the hottest planet in our entire solar system. The truth is that actually it isn’t though it’s still pretty hot in comparison to the other planets that orbit around the Sun. We already know that Mercury is the fastest planet in our solar system (if we’re considering how long it takes to orbit the Sun), as well as the smallest planet in it too.

But just how hot is Mercury’s surface in comparison to Earth and the other planets? Well, we’re going to be looking at the temperatures it can reach, as well as looking at some other planets here too.

The truth is that the temperature on the planet Mercury varies drastically throughout the course of a day, much more so than Earth. At its hottest, the temperature on the surface on the planet can get as high as 820° Fahrenheit (438° celsius) during the daytime on Mercury.

But it doesn’t stay this hot throughout the whole day. In the coldest temperature during the nighttime on the planet, it can get as cold as 290° Fahrenheit (180° celsius). This just goes to show how drastically different the temperatures can be on a planet, even when it’s only a little over 36 million miles away from the Sun (for reference, the Earth is 93 million miles away from the Sun).

This is just one of many interesting planet Mercury facts. It is often assumed that because of its close proximity to the Sun that Mercury is going to be the hottest planet in our solar system. Actually, this isn’t true, as Venus has been recorded as having higher temperatures during the daytime.

The average temperature on Venus 864° Fahrenheit (462° Celsius), so not much different. Considering it’s quite a bit further away from the Sun though, this usually surprises most people.

It’s a good question, especially when you consider the difference between the hottest and coldest temperature on Earth. They may feel like a lot to us, but the reality is that there’s not too much difference for us, which is obviously crucial to our survival. Now, if I say that the temperatures on Venus vary even less and tend to stay steadily hot, that kind of gives us our answer to the question.

The lack of an atmosphere to retain the heat is the key reason why the temperature on Mercury varies so much throughout the course of a year. Unlike Venus, which has a very thick atmosphere to retain all of the heat of the Sun, all Mercury has is a very thin exosphere which is unable to retain the heat.

This means that when the Sun does glare down on the planet, it gets hot very quickly. But in the times where the Sun isn’t within close proximity of Mercury, all of the heat from its surface is allowed to escape. This results in a really cold temperature on its surface – much colder than both Earth and Venus, despite it being closer to the Sun on average.

All in all, the truth is that the surface temperature of Mercury still can get very, very hot during the daytime on the planet. It’s much hotter than on Earth, and unless we suddenly gained the ability to be completely resistant to fire, it’s unlikely that we could ever visit the planet properly. However, many people aren’t aware that Mercury can also get much colder than Earth too, which is often a surprise considering how close it is to the Sun.