This episode of SciShow is made in partnership with our friends at What’s  Watt, a show about electricity.

You can head to their channel and learn  more about this important yet invisible topic by clicking the link in  the description down below. In 2021, the Parker Solar Probe  fulfilled its mission to “touch the Sun”.

Okay, technically it dove into the corona,  which is the Sun’s upper atmosphere. But touching the Sun is how NASA  described the accomplishment. And what an accomplishment it was.

Temperatures in the corona are  over a million degrees Celsius, hundreds of times hotter than the  highest melting point of any metal. So, why the heck didn’t it melt? [♪ INTRO] Part of the answer is technology. Parker’s got a high-tech  protective shield made of a super light carbon foam that’s  really good at staying cool.

But even this shield couldn’t survive  anything close to a million degrees. And luckily, it didn’t have to. Because  physics saves the day another way.

Thanks to physics, it’s possible  to have hot without heat. In everyday life, we tend to mix up the two. When temperatures shoot up,  we complain about the heat.

But when it comes to physics, temperature  and heat are two very different things. When something is hot, like a driveway or the air, that means its particles  have a lot of kinetic energy. Basically, they’re zipping around really fast.

So, temperature is a property of a substance. But heat is something else: It’s  a process of transferring energy between two things with different temperatures. Like, if you run barefoot down a  scorching driveway to pick up your mail, the particles from the concrete  will bump against your skin, transfer some of their energy,  and make your skin heat up.

Heating can happen a few different ways, but how much heating depends on both the heat source and the thing being heated. Two substances with the same  temperature won’t necessarily cause the same amount of heating. Like, you can stick your hand  in a hot oven and the air won’t burn you, but the hot pan sure will.

That’s because air is way  less dense than solid metal, so it has way fewer particles bumping  into your skin at any given moment. Compared to the pan, it would take way longer for the air to transfer enough  energy to your skin to burn it. This is the main reason why the Parker Solar Probe can survive six-figure  temperatures: the particles in the Sun’s corona are incredibly few and far between.

The density over there is like ten trillion  times less than Earth’s atmosphere! So even though each individual particle  will pack a punch whenever Parker does collide with one, collectively there aren’t  enough collisions to heat the spacecraft up to metal-melting temperatures… at least  not during a relatively short plunge. During its first visit, Parker dipped  into the corona for a few hours.

But its heat shield never got hotter  than about 1400 degrees Celsius. And thanks to that shield, the inside of the craft chilled at a mere 30 degrees Celsius. In other words, this probe  stayed around the temperature of an average summer day while it blazed  through the atmosphere of the Sun.

Maybe one day engineers will design  a much more complicated craft that lets a bunch of squishy humans  visit the Sun without melting, too. Thanks to What’s Watt for  supporting this SciShow video! What’s Watt is a YouTube  channel powered by Nexans, a leading cable company committed  to promoting sustainable energy.

It’s hosted by Frederic Lesur,  one of their top engineers and science communicators, and also features some science YouTubers you might already know. It’s the perfect intersection  of YouTube nuts and science fans like what you find on this  channel that you already watch! If you don’t have time for the comprehensive,  in depth science of electricity, you can check out their “Ask me  Watt” series where they find answers to your electricity questions and introduce  you to fun facts about electricity.

If you’re still tucked into spooky season, you can watch their Ask Me Watt  episode about electricity fears. You can find that video and more in  the link in the description down below. And thanks for watching! [♪ OUTRO]