eli5 why is the Great Red Spot on Jupiter glowing?


From the James Webb, this picture in infrared. Why is it glowing?


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You’ve probably heard the phrase “red hot” before. If you’ve ever watched a blacksmith heating metal, you may have see how it begins to glow a dull red, then brightens before turning yellow and finally white. These colors actually correspond to particular temperatures, which is why blacksmiths often work in the dark: it lets them see the color of the glowing metal better, and they can use that to gauge how hot it is.

Although Jupiter is not known for being hot by Earth standards, the Great Red Spot is actually very hot. It’s not hot enough to glow visibly, but it *is* hot enough to glow in the infrafed. That’s why it shows up so brightly on infrared cameras like the ones JWST uses.

The Red Spot is a 10,000 mile wide storm that is going on in Jupiter. Consider: a category 5 hurricane in Earth can reach 157 miles per hour or more, and can flatten entire states. The Red Spot’s wind speeds can reach **268** MPH. That’s a lot of kinetic energy in the wind, which translates into a lot of heat energy that can be detected by infrared cameras.

The photo is telling us that the Great Red Spot is warmer than everything else in the photo. That much is clear. As to why it is warmer, that’s actually not a very well understood phenomenon. Scientists have some educated guesses, but it is far from a solved problem. I can give you the ELI5 for the best guess we have at the moment:

Rub your hands together a lot. They get warm, right? The friction causes them to heat up.

The Great Red Spot is essentially a giant planet-sized hurricane or typhoon. The chaotic swirliness of this tremendous storm makes it exceptionally noisy. The sound waves from all the noise causes shaking in the high atmosphere above the storm, and that shaking has a similar effect to rubbing your hands together, which heats it up. Since it’s happening high up, that means this warm layer is on top, and when we take a photograph of the planet from far away, the layer on top is the one we see.

In reality, the actual storm is much colder than the rest of the planet is. The storm just happens to be covered by a warm “lid” that shows up in photographs.