Why are there black patches on the suns surface?


Why are there black patches on the suns surface?

In: 1

They are cooler spots ~~amused~~ (edit: *caused*- but I like the typo) by magnetic activity it’s thought. But only cooler in comparison to other parts. They appear darker compared to the surrounding brightness. If you took the spot on its own it would still be bright and light.

There aren’t. Or at least it depends on what you mean by “black”.

Sunspots are cooler spots on the Sun’s surface. Since the Sun glows because of the heat of its material, those regions glow much less than the surrounding parts of the Sun. That makes them appear black *relative to the rest of the Sun*, but they’d still be dazzlingly bright if you were “standing” on them (not that you can stand on gas, but you know what I mean).

As for why sunspots are a thing: they’re not fully understood, but they’re believed to be manifestations of the Sun’s magnetic field. Since the “gas” in the sun is actually electrically-conductive plasma, it flows according to both electromagnetism and fluid dynamics, which makes the magnetic field of the Sun visible in its flow.

Those black spots are called “sunspots”. The sun constantly produces radiation and intense magnetic fields. Sometimes the magnetic field in certain spots is aligned and intense enough to cause that part of the surface of the sun to drastically drop in temperature (to anywhere between 25%-50% of its normal temperature). Even though this is still extremely hot and would normally appear very bright, because of how bright all the surrounding surface of the sun is, it appears very dark when we view it.

People have already mostly answered the question, but didn’t clarify why they look black compared to the rest of the sun.

When you are looking at pictures of the sun, you are seeing it taken through very strong filters. Think of it like very dark sunglasses, or a welding lens. It makes everything much, much darker than normal.

If you look at a “bright” light bulb through a welding lens, you likely will barely be able to see it, and then only because everything else is blackness. Look at a welding arc though, and it will still be fairly bright. Take off the lens, and both will be bright on their own, only the bulb would be completely washed out by the welding arc, and you’ll be blinded in short order.

The sun glows in part for the same reason hot cinders in a campfire do. Warm things glow. The hotter the thing is, the harsher it glows, and the higher wavelengths it emits. It’s called blackbody radiation.

You and everything around you are glowing right now, you just don’t see it because the glow of room-temperature stuff is only visible in infrared. This is the light that night vision cameras can see. Get something hotter, and it will start glowing in wavelengths that your eye *can* see. Hot coals, as well as the sun, are definitely hot enough to do that.

If you poke a hot coal in a campfire from a safe distance with some kind of long stick-like tool, particularly metal ones, you may notice that the spot you poke stops glowing and turns black. That’s because the heat from the part you poked is draining away into the stick. This lowers the temperature of the coal at that spot, which causes it to glow less brightly, and probably stop glowing in visible light altogether.

This is what sunspots, those “black patches” on the sun, are. Colder spots. They glow less brightly than the hotter spots.

Now, “colder” here is obviously relative. You would be just as vaporized in a sunspot as you would be anywhere else on the Sun’s surface. It’s just not *as* hot there.