How can the empty space around the sun be millions of degrees hot and the surface only thousands ? it doesn’t make any sense.
In: 96
I always assumed it was cause the particles are moving faster in the medium of the Corona, less drag.
I out of thin air answer but if you looking for a frame work that can make sense tempture is simply a measurement of the energy level of atoms in an area
In general a gas > liquid > solid are different levels of energy you can intact with a key thing is how many atoms are in an area as temperature increases the density drops leaving fewee atoms in an area now if you apply 100 heat units. The gas density is 30 atoms in the area, liquid is 100 atoms and solid is 200 atoms.
The gas temp would go up roughly 3 heat units the liquid 1 and the solid.5.
This breaks down the temperature difference but have to hit the I believe for how you get this to happen sadly. One day we’ll figure it out.
Here’s a simplified breakdown:
The surface of the sun is like a fire, simply put, with fuel constantly bubbling up from below and continuing the blaze. Like all fires with consistent and steady fuel supply, the temperature remains relatively stable so long as there’s a stable and consistent balance between the smolder and the fuel. This process will go on and on for as long as the fuel is abundant.
Now the fire doesn’t just get hotter and hotter. It is dispersing the heat it produces constantly. This heat is expressed in various ways, whether it be through electromagnetic radiation or via ‘smoke’ (for lack of a better descriptive term but fitting in that it exhibits the concept well) which can be described as spent fuel or byproducts of combustion that get ejected out of the fire as a byproduct of the reaction taking place.
So, in essence, you have two cool materials, they interact, and become a different chemical composition and heat is produced in this process. The original fuel (think oxygen + gasoline) is burned and you produce heat and smoke. The temperature at the level of the fire, however, is relatively constant as it does not hold on to the heat it produces. And therein lies the bulk of the answer you are looking for.
As other commenters have outlined, and are way too technical for an ELI5, they bring in the fact that we cannot adequately explain the nuance to this… But it is indeed well-conceptualized as follows:
The heat produced by the smoldering blaze is not held within the fire itself but ejected outward as previously mentioned, in the form of light/radiation and of course particulate matter as well. This particulate matter (again think of smoke) is exceedingly hot as it is carrying some of the heat energy produced by the fire. This is what is accumulating in the outer atmosphere (again an inaccurate term, per se, but descriptive) of the sun itself. A similar conceptualization could be that of greenhouse gases accumulating on earth, holding on to acquired heat energy leading to global warming (an inaccurate example, but illustrative nonetheless).
TLDR: Sun fire can be likened to combustion where fuel==>reaction= byproducts + heat. Byproducts are hotter than original fuel and carry heat to atmosphere but are held there due to gravity/magnetosphere/solar convection patterns and accumulate leading to massive temperature elevations beyond that of the fire/reaction itself.
At the surface of the sun, the magnetic field lines look like many loops rising up out of the surface into the atmosphere — and these loops are changing all the time. If the loops touch each other they can cause sudden explosions of enormous amounts of energy that heat up the atmosphere
(For what it’s worth, I wrote a Ph.D. dissertation on this topic.)
TL;DR: The most likely explanation is that the energy in the very strong magnetic field in the corona is being transformed into heat.
In plasmas like the solar corona, you can think of the magnetic fields (and the ionized gas, or plasma, attached to the fields) as being like elastic bands. Convection beneath the surface of the sun causes twisting of the magnetic field lines, building up stored energy. Eventually, in some regions of the corona, very large electrical currents are able to flow, leading to a rapid dissipation of the magnetic energy and a relaxation of the tension in the magnetic fields. This energy goes into heating the particles, leading to the hot corona. The corona is very tenuous, so it doesn’t take a lot of heat to make the temperature much hotter than the underlying chromosphere and photosphere.
The specifics of how, why, and where the current flows are still not fully understood and this has motivated several recent space missions. Also, the process by which magnetic energy rapidly transforms into heat (the process of “fast reconnection”) is an area of active and ongoing research.
What surface? The sun is a moving ball of gas.
It doesn’t make sense because you are thinking something hot would feel hot. It wouldn’t feel that hot if you stuck your hand it it. There just isn’t much “there” to feel, it’s almost a vacuum. But the few molecules of gas that are there, are moving really really fast, which is how you measure temperature. The same thing happens in the upper atmosphere of the earth actually. The “temperature” of the upper atmosphere is thousands of degrees but you wouldn’t notice it passing through.
The hottest point of a flame is not the bottom. The energy of the flame and the sun are not fully released until later in their cycle, not at the initial point of “combustion”.
Heat is kind of a made-up number. Temperature is the *average* of the *kinetic energy* of a very large number of particles. Kinetic energy is mass times speed times speed.
But knowing the *average* kinetic energy doesn’t tell you how fast any individual particle is moving:
## One
Some particles may be moving very fast, and some particles may be moving very slow, so that there are *no* particles that actually have the average kinetic energy.
Or you might have *every* particle carrying *exactly* the same kinetic energy as every other particle.
Or you might have what’s called a “thermal distribution”, where some particles move a little faster than average and some move a little slower, but they form a bell curve (not quite a traditional “Gaussian” bell curve, but a specific shape called a “Maxwell–Boltzmann” curve).
“Temperature” as a concept is really only valid for groups of particles that fit the Maxwell–Boltzmann curve, a “thermal distribution”. Non-thermal distributions naturally become thermal distributions when given enough time.
But the Sun’s corona — the part that’s “hotter” than the surface, and “almost as hot” as the core — is **not** a thermal distribution. Energy is actively flowing through it, and it’s being whipped around by strong magnetic winds (which can change the kinetic energy of individual particles). The concept of “temperature” is already a little bogus in the corona.
## Two
The average kinetic energy also doesn’t tell you **anything at all** about how much kinetic energy the whole *group* of particles has: you don’t know if it’s a huge number of particles or a small number, and you don’t know if they have a high heat capacity or a low heat capacity.
Heat capacity is not quite the same thing as mass, but they’re related by a function called the “specific heat capacity”. The specific heat capacity function is almost a constant for any given substance (except at phase changes, like ice melting to become water). It basically measures how much of the kinetic energy “leaks” to become potential energy trapped inside the particle. When the outside cools back down, the particle will release that energy by converting it back to kinetic energy.
In short, there’s a very big difference between putting your hand *in* a 450°F / 230°C oven, versus *touching the inside* of a 450°F / 230°C oven.
First, air is less dense than metal or ceramic, so there is less air mass touching your skin when you hold your hand in the oven for a few seconds, versus the much higher metal/ceramic mass that would be touching your skin if you touched the oven itself.
Second, air has lower specific heat capacity than metal or ceramic, so the air that’s touching your skin also contains less hidden potential energy inside of its particles than the oven does, even if you compare equal masses at equal temperatures touching an equal surface area of your skin. (The high heat capacity of the walls of an oven is what lets it maintain a constant temperature during baking. It buffers the interior of the oven from changes in temperature.)
## Back to the main point
The Sun’s corona is incredibly wispy and thin. Compared to standing on the surface of the earth, the corona is a hard vacuum: it’s about ten million million (I didn’t stutter) times thinner than Earth’s atmosphere at sea level. The Sun itself, even the relatively thin photosphere (visible surface), is much, much denser than that: about six thousand times thinner than Earth’s atmosphere at sea level at the Sun’s surface, and *much* denser than Earth’s atmosphere at the Sun’s core.
So the temperature wouldn’t actually cook you *just* because it’s hot, at least not very quickly.
If the corona’s kinetic energy *were* thermally distributed, you would *eventually* heat up to being just as hot as the corona… but it would take a very long time, longer than it would take to heat up just from baking in the direct sunlight. (Direct sunlight would only put you at 5,000 K or thereabouts, but it would do it very very quickly, depending on the color of your clothes and the asymmetry of them from front to back. Afterward the corona would *technically* keep making you hotter once you reached 5,000 K, but you’d already be too dead to notice.)
But the corona isn’t thermally distributed, so I don’t think you could meaningfully heat something up to 5 million K or whatever it is that the corona’s “temperature” is measured to be. It probably caps out lower than that, but goes higher depending on how electrically conductive you are. The non-thermal distribution of particle energies means that “average kinetic energy” and “what temperature will an object reach if left in contact” split apart into two separate numbers, i.e. the math gives up and shrugs and says “it depends?”.
## Epilogue: Oh yeah, why does it do that?
We don’t know the details, but it definitely has to do with the magnetic fields. They accelerate some particles to high speeds (= high kinetic energy), decelerate others, and leave others untouched. This keeps the corona from being the same as itself as you move around in space or time. It’s constantly changing. And while the magnetic fields dump a *lot* of potential energy into the corona, they do it very unevenly. We just don’t know why the magnetic fields are quite so strong, since we’re still trying to figure out the dynamo effect (our best guess for where the magnetic fields come from), and we don’t know how to predict the behavior of the magnetic fields over longer periods of time. (They look chaotic. See [this YouTube video for more about chaos](https://www.youtube.com/watch?v=-RdOwhmqP5s).)
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