Things on Earth being ‘As hot as the sun’


I’ve heard a few times now in various scientific fields, mainly experiments, about things getting as hot as the sun.

How is this possible? Surely if you do something and you create heat that is that hot it would melt anything surrounding it?

Would love to know how this works 🙂

In: 175

Just because it reaches the temperature of the sun doesn’t mean it has the same energy as the sun. It’s a not a miniature sun on earth, the experiment might be a few milligrams of material reaching that temperature for a few milliseconds, a negligible amount of energy that can probably be absorbed by the air surrounding it. Also yes, some of these experiments use equipment that’s “single use”, it’s expected to be destroyed by the heat.

The surface of the sun is “only” about 5000 degrees C. As far as astrophysics numbers go, this is pretty tame. This is hot enough to melt just about any container we can create for it, but you can always levitate it in an electromagnetic field and there are certain ceramics that can survive close to these temperatures. A small object at this temperature would put out about as much heat as, say, a burning house, so as long as you were a few dozen feet away you’d be fine.

The core of the sun, at 15 *million* Celsius, is another story. We’re certainly capable of creating environments this extreme, but it’s far more challenging. Magnetic fields become pretty much the only option to contain anything heated up to this extent. As far as destructive power, A brick of charcoal magically kept at this temperature would put out (very roughly) as much energy as a forest fire the size of a state. Containing anything at this temperature is a genuine engineering challenge involving ingenious heat dissipation and cooling methods.

“as hot as a sun” is a rather broad term. Is it hot as its surface (i.e. few thousand of degrees celsius)? Or is it as hot as a stellar core (within tens of millions of degrees)?

Either way, you can have that temperature happen for a very brief moment, you can have the stuff isolated in a vacuum/magnetic confinement, you can have an active cooling system that will keep the walls from melting down. And probably a few other ways/combinations of them that I might not be aware of right now.

The main way is magnetic confinement. You use a magnetic field to levitate the hot thing in a vacuum so it doesn’t touch the walls of the container. The only way it can heat up the container is by thermal radiation, but this can be mitigated with a reflective surface to bounce the radiation back

The amount of radiated energy from an object depends on its surface area, you can feel the difference between a candle and a large fire.

The energy flux (energy flowing through an given area) drops with the square of the distance. If the distance doubles the energy flux is 1/4. if we compare 1cm to 1m =100cm is 100^2 =10,000. So an object of the same size will receive 10,000 times more energy if the distance is 1cm compared to 1 meter.

The sun’s diameter is 109 times the Earth’s diameter so an enormous area, which is why it emits so much energy. The distance is 150 million km =23454 earth radius. So you do not have a noticeable effect if you just move around on Earth, the energy flux it practically constant at earth’s distance from the sun.

Warmer than the sun is in general warmer then the surface of the sun that is 5,772 K, 5499C, 9929F.

If you do arch welding the center of the electrode might be 5000-6000C which is warmer than the surface of the sun. A plasma cutter can reach 14000C, and both of them will melt stuff that is the point.

The arch and plasma are not that large in surface area the radiation energy is not that larger. So it will melt stuff very close to it but when you get away the energy flux quickly drops

If you have something with the temperature like the surface of the sun that is quite large on Earth it will destroy stuff around it too. But that is not something that is common at all, the best example would be an exploding nuclear bomb. Even a small nuke like the one that exploded over Hiroshima had thermal radiation that vaporized people, you get 3rd-degree burns and a distance of 2 km

So most object as warm as the sun on earth is like a candle compared to the sun which would be more like a house fire. You need to be extremely close to the candle to get the same energy as a lot longer distance from the sun.