[ELI5] Would something stay hot in the space forever since there is nothing to transfer its heat?
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As other comments have said, radiation will still dissipate some heat over time, but I think it’s worth mentioning that you’re absolutely right that with almost no matter to conduct or convect away the heat it would stay hot for much longer.
In fact, (and I’m not a rocket scientist, just a physics student, so most of my knowledge about this comes from being a fan of The Expanse) I’m pretty sure getting rid of excess heat is a major issue in space travel, because everything we do to keep ourselves alive and comfortable generates waste heat, there aren’t many good ways to speed up radiative heat loss, and getting rid of heat in other ways requires us to dump that heat into some limited substance and jettison it.
Anyone with a less sci-fi-based understanding feel free to correct me here, but I think the principles are ok.
Everything emits light with intensity directly proportional to how hot it is. Even you, or a loaf of bread. The phenomenon is called black body radiation, and it is why metals “glow” when they are super hot. Cold objects don’t emit very much light, and it is lower intensity. But it takes energy to create light. Everything is slowly losing energy by this process. Since light can travel through a vacuum, stuff still loses energy in space.
Side note: Objects in orbit with the sun hitting them will be heated to 120C. Heat is generally bad for electronics, so a lot of thought is put into cooling stuff in space. The solution is basically a heat sink that operates using black body radiation instead of air cooling. You can dump a significant amount of energy with a big enough surface area pointing away from any heat sources.
To add to what others have already said, one of the structural challenges of the ISS is that it is at 200C on the side that is facing the sun and -100C on the side facing away from the sun (the numbers might be off, but you get the idea)
To add to what others have already said, one of the structural challenges of the ISS is that it is at 200C on the side that is facing the sun and -100C on the side facing away from the sun (the numbers might be off, but you get the idea)
Heat is energy in transition, Most of the electromagnetic radiation that comes to the earth from the sun is invisible. Only a small portion comes as visible light.
The transfer of heat by radiation, which takes place with no material carrier. when you have heat, you will always have light. Light can travel through empty space.
Heat is energy in transition, Most of the electromagnetic radiation that comes to the earth from the sun is invisible. Only a small portion comes as visible light.
The transfer of heat by radiation, which takes place with no material carrier. when you have heat, you will always have light. Light can travel through empty space.
I believe it’s called black body radiation. Essentially energy lost as electromagnetic waves.
It doesn’t need a medium to convey through.
I believe it’s called black body radiation. Essentially energy lost as electromagnetic waves.
It doesn’t need a medium to convey through.
Ever seen a white hot piece of iron? Even in absence of conduction and convection, that radiation of light still transfers heat away. And nothing ever really stops glowing that way, it’s just that as the temperature goes down the light emitted gets redder and we can’t really see infrared with our eyes. With a thermal camera you can however.
Accelerating charges radiate electromagnetic waves. If you have some material that is made of atoms above 0K they are oscillating. Thats what we call temperature. And the occilation is called thermal motion. Now we got charges that are always accelerating back and forth. They radiate. Thats what we call thermal radiation.
This energy comes from the motion of charges so they behave like lightly dampened oscillators. They emmit light and slow down.
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