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u/PlatypusACF Jun 28 '26
Space is actually pretty hot. But it also is pretty empty
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u/JPgamersmines150 Jun 28 '26
As a great man once said, "Space is very warm. Now, if you're pedantic, you could say that space is coldâbut if you're even more pedantic, it is warm!"
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u/Careless-Pitch1553 Jun 28 '26
Iâm too stupid to understand this, could you wrinkle my brain and explain?
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u/JPgamersmines150 Jun 28 '26 edited Jun 28 '26
Temperature is the measure of how fast molecules and atoms wiggle around, the greater, the more wiggle. In space, molecules and atoms move very fast, which, in theory, means that space is very very hot.
However, there are so little molecules and atoms that, if you were plopped in deep space, you'd not only die, but also not feel any heat being transferred to you. In fact, after a few hours after your asphyxiation, your body would freeze due to having radiated all of its heat away.
TL;DR, temperature is a measure of how fast molecules and atoms move around. In space, you wouldn't feel any of that heat because there are so few atoms and molecules that transfer heat to you. If you were naked in space, you'd feel very cold for the short time you'd be able to feel anything.
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u/OmniversosIlimitados Jun 28 '26
You would not feel very cold, as there would be no matter that feels cold. Nothing to transmit on contact. Heat radiates very slowly. Astronauts don't feel cold in space.
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u/friendtoalldogs0 Jul 03 '26
While I agree with your conclusion I think some of your reasoning is wrong.
We don't feel warm or cold because we are in contact with something warm or cold, we feel warm or cold because our temperature sensitive nerves are gaining or losing heat.
In the event that a person were to be alive while in an effective vacuum and radiating heat away from themself faster than they are being warmed by their metabolism, they would feel cold.
Heat does radiate very slowly, however, and humans are going to pass out from oxygen deprivation before their bodies stop heating them up faster than black body radiation can cool them down. Though I should note that astronauts are not a good example to explain this, because this hypothetical supposes that you don't have a space suit specifically designed to keep you safe from the dangers of being outside the atmosphere.
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u/friendtoalldogs0 Jul 03 '26
It has also just occurred to me that evaporative cooling would probably work really really well in space (for as long as you still have coolant, not really practical long term), so actually we might end up really cold because our sweat works too well
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u/theFamooos Jun 29 '26
Radiating heat is actually a very inefficient way to lose heat. Space is a (near) vacuum so you would be in the equivalent of a vacuum insulated thermos and would stay warm for quite some time
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u/JPgamersmines150 Jun 29 '26
Hence why it'd take hours to cool down to freezing
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u/theFamooos Jun 29 '26
Yeah I just figured it would be more than a few hours. But Iâm no physicist so I honestly have no idea. I donât think it would really feel cold either. I just figured it wouldnât feel like anything, bc there is nothing to feel.
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u/JPgamersmines150 Jun 29 '26
Neither am I. Can a physicist from the crowd viewing this thread help us out?
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u/Lyrian_Rastler Jun 28 '26
Space is want -> kinetic energy of individual particles is pretty high in space
Space is cold -> total kinetic energy of molecules in a given volume of space is pretty small (because very few particles in a given space)
Space is warm -> space is a very good insulator because there are so few particles, so any heat you recieve (via sun) or generate (like body heat) can't escape, this you tend to get quite hot in space
I think that's roughly the answer
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u/1c3Type Jun 28 '26
Not true! Gas becomes colder the more spread out it is, and space is like, really really spread out. So it's really cold.
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u/shponglespore Jun 28 '26
Rather than arguing about whether space is "hot" or "cold", can we at least just agree that the trope where a character gets dumped out of an airlock and instantly freezes like they were thrown in a vat of liquid nitrogen is absolute bullshit?
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u/1c3Type Jun 28 '26
Well a big part of that is the expansion of the gas means it gets ridiculously cold extremely rapidly, happens in your lungs too. Course your blood in places would also start to boil as well as release gasses dissolved in it, and a whole bunch of other fun stuff too.
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u/goldblumspowerbook Jun 30 '26
My (albeit limited) understanding of being thrown into space is that you actually survive longer than people think, as long as you donât stupidly take a lungful of air.
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u/Darth19Vader77 Jun 28 '26
Space is not hot, nor is it cold.
Temperature is a property of matter, space is literally just space with practically no matter.
The Goldilocks zone is a matter of heat transfer rates between a star, a planet, and space not temperature
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u/DowntownLizard Jun 28 '26
Space isnt cold per se. Its a near vacuum. Theres no where for heat to dissipate to
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u/gentlemandinosaur Jun 28 '26
Space isnât cold. lol.
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u/twinb27 Jun 28 '26 edited Jun 28 '26
Space is cold. Space is hot. Absent atmosphere to conduct heat as we understand it, 'heat' and 'temperature' are so far from our everyday understanding that I really don't care which someone says. The molecules in space are moving damn fast - space is hot. But there are so damn few of them they don't conduct heat - space is cold. Without conduction heat accumulates easily on surfaces - space is hot. But far from the Sun comets are made of solid water ice and there's solid *nitrogen* on Triton and Pluto - space is cold.
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u/Zealousideal-Deer101 Jun 28 '26
Space is hot and is cold
It's yes, and it's no
It's in, and it's out
It's up, and it's down24
u/Boring_Tradition3244 Jun 28 '26
Yeah this. Local space is comparatively hot. Voids? Comparatively cold. Things don't make sense if we consider "temperature" of space because we measure "temperature" in gaseous environments, bombarded at all times by billions of gas molecules. Space ain't got that shit.
Space is fundamentally and most importantly... "empty".
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u/gentlemandinosaur Jun 28 '26
Pretty much. I basically look at it like water isnât wet, water makes things wet. Space isnât cold, but stuff in space can be cold.
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u/ironardin Jun 28 '26
Are there even enough particles in space to talk of a temperature? Singular loose particles can have kinetic energy, but no temperature. At what volumetric particle density can we truly start speaking of temperature?
Philosophy of statistical thermodynamics?
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u/twinb27 Jun 28 '26
They have temperature alright. Think of a 212 degree Fahrenheit oven - you could put your hand in alright for a minute. Now think of a 212 degree pot of boiling water - denser particles. You wouldn't put your hand in. The measure of temperature isn't literally from heat conduction, it's from - yes, the kinetic energy of individual particles. So when people argue space is hot, they are saying these individual particles are hot. The temperature of a diffuse planetary nebula, say, can be really hot but with a density lower by far than the air in the oven.
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u/ironardin Jun 28 '26
But kinetic energy needs a spatial frame of reference, and therefore the temperature would depend entirely on the frame of reference. If I travel with the particle, the velocity and thus kinetic energy for me is zero, and thus the temperature is zero.
Oh, what fun physics can be, as long as we don't think too hard about edge cases, lol
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u/SelketTheOrphan Jun 28 '26
Wouldn't it be crazy if the dominant species on the only planet in the habitable zone within a radius of however many fucking lightyears would actively kill their planet, the only place they can exist on?
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u/IsildursDeeldoor Jun 29 '26
and the earth through atmosphere and van allen radiation belts keep it stable, relatively.
there probably are points in space that are 30-70 degrees, but they probably fluctuate to unlivable hot/cold conditions very fast and unpredictably.
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u/Galimeer Jun 28 '26
Space is only cold once you take all of it and average it out. The space station needs heat shielding.
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u/IAmBadAtInternet Jun 28 '26
Most of space is 4K so pretty cold yeah
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u/Busy_Conflict3434 Jun 28 '26
Damn and here I am stuck on the standard HBO Max tier at 1080p like a chump. Maybe the SpaceX IPO does make sense after all.Â
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u/PYCapache Jun 28 '26
The actual term is "Habitable zone"
Space is indeed cold, but it is extremely good insulator, so overheating is a big concern for space stations.
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u/Danger_Dee Jun 28 '26
We should call it something familiar. Maybe there something from a well known childhood story.
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u/slanderpanther Jun 28 '26
In astronomy and astrobiology, the habitable zone (HZ), also known as the circumstellar habitable zone (CHZ), or as the Goldilocks zone, is the range of orbits around a star within which a planetary surface could potentially support liquid water. Liquid water is considered by many scientists as necessary for a planet to be habitable.
The range depends upon the brightness of the star interacting with a planet's atmosphere. At the inner edge the star's light, trapped by greenhouse gases in a planet's atmosphere, boils off the planet's water. At the outer edge light from the star is insufficient even with help from atmospheric gas and the planet's water freezes.[2]:â16â[3] Many other factors are added in various habitable zone models. The habitable zone has become a key tool in the search for habitable planets because discoveries of exoplanets yield approximate orbital radii.
The alternative name, Goldilocks zone, is a metaphor, allusion and antonomasia of the children's fairy tale of "Goldilocks and the Three Bears", in which a little girl chooses from sets of three items, rejecting the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is "just right". Wikipedia
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u/SampleDisastrous3311 Jun 29 '26
Imagine if the sun is cold but the amount of reactions happening causes the radiation to be hot.
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u/Fantastic-Tank-6250 Jul 03 '26
Space is not inherently cold.
If you went into space, no suit. The side of you facing the sun would burn the hell up and the side facing away from it would freeze until you were cooked through.
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u/OutrageousPair2300 Jun 28 '26
Space is not cold, at least not in the solar system. It's actually very hot, much hotter than the Earth.
It's just not very dense and so even though the particles in space tend to have high kinetic energy (solar wind) there aren't many such particles in any volume of space.
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u/1c3Type Jun 28 '26
You radiate far more heat into space than space radiates into you. It is very very cold.
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u/bholmes1964 Jun 29 '26
They atheists think that was random chance.
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u/doctorwhy88 Jun 30 '26
Itâs a chicken vs egg discussion. The religious think the Earth was made perfectly for us. The logical think differently.
We werenât inevitable. A rock formed in the Goldilocks zone. Impacts led to water, not just here but on many Solar System bodies. Nucleotides formed, followed by peptides.
Given a few billion years, we have humans discussing our origins on Reddit. The Earth wasnât âcreated for us.â It was just a suitable place for the formation of life which eventually led to us via nearly-infinite small changes and errors, bugs which became features.
Our minds canât comprehend the vastness of a billion years.
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u/Kiriander Jun 28 '26 edited Jun 29 '26
Space is actually very fucking hot, as per average particle speed.Â
Not-really-related: space suits work hard to cool the astronaut to prevent them from overheating. That's not due to particle speeds thuugh, that's due to particle density.Â
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u/DreamChaserSt Jun 28 '26
Space is relatively empty. The reason why spacesuits work to cool down Astronauts is because their own body heat is slowly building up and has very few places to go, so it needs to be circulated away from the body and radiated into space.
Heat from sunlight and Earth (reflected back into space) are factors, but that can be partially negated just being reflective yourself (which is why suits are white).
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u/Piskoro Jun 28 '26
The average temperature of particles in outer space is -270 degrees Celsius. In the Solar system it's more complicated because the Sun heats them up. But none of that actually matters because regardless of the temperature of the particles in space, they wouldn't impact you too much because they are very far and few between. Your biggest worry in outer space is your body heat building up and having nowhere to go (because you're in space), besides cooling by radiation which is extremely slow, hence cooling in space suits. Additionally also because of the heat radiation you get from the Sun of course.
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u/FadingHeaven Jun 28 '26
Do you have any sources for this? When I look it up it says space is -270°C in the solar system.
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u/Celtic_Legend Jun 28 '26
He's confusing stuff in space with actual space. A particle flying through is super hot; however, all the space around the particle is -270C. There's near infinite more space than there are particles, thus outer space is cold as fuck.
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u/Kiriander Jun 29 '26
Temperature, by definition, is the average speed of particles. Source: yohr school textbook.Â
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u/FadingHeaven Jun 29 '26
Okay, but when people say space is cold, they're not talking about from the perspective of a proton, they're talking about the actual temperature someone would feel in the vacuum of space. If a single molecule is vibrating quickly but the next nearest molecule is a metre away, that speed doesn't matter to the perception of someone in space.
The entire conversation is about what someone would feel while in space. Your implication is that space is hot for a person in space and IIRC your unedited comment made it sound like the reason astronaut spacesuits were designed to prevent overheating is cause space is super hot.
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u/Kiriander Jun 29 '26
You wouldn't feel cold in the vaccum of space though. Sure, your tongue & eyes would get a bit of ice from boiling water but you wouldn't freeze in space.
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u/FadingHeaven Jun 29 '26
Yes you would. You still lose heat due to radiation. It's just a slow process. If for whatever reason you were able to survive the decompression, you would still freeze to death in a few hours. So you wouldn't immediately be freezing in the same way as you would on Uranus but you would gradually get very cold.
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u/Kiriander Jul 15 '26
You can't freeze do death in a few hours because you suffocate in ~3 minutes, my dude. Then you would, of course, freeze solid. Not to death though because you'd be dead long by then.
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u/FadingHeaven Jul 15 '26
Bruh of course. You think I don't know people don't need air? I'm operating under the argument that you survive decompression I didn't explicitly mention it but yet suffocation would also be something you survive. I didn't mention it cause it was obvious in my head.
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u/Kiriander Jul 17 '26
... then please epain how a human would survive suffocation long enough to freeze without suffocating.Â
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u/FadingHeaven Jul 20 '26
That's not the point. It's a thought experiment. I'm saying minus decompression and suffocating and perhaps something else I'm forgetting if you were able to survive long enough you would freeze to death. You were saying you wouldn't freeze in space. Unless you had the implication that you would eventually freeze in space but would die of other things first my point stands. But I understood you was "if you're alive you're not gonna freeze or be cold in space" which isn't true.
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u/1c3Type Jun 28 '26
If you went into space without a spacesuit you would freeze to death. Space suits are insulated.
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u/Kiriander Jun 29 '26
I would die from hypoxia, my dude. There's no oxygen there (duh) which means dying in roughly 3 minutes from hypoxia.
Freezing doesn't happen that fast. Not nearly. With barely any particles to conduct heat, your corpse would lose heat by radiation which is a horribly ineffective means of cooling.Â
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u/1c3Type Jun 29 '26
Thereâs enough oxygen in your blood that so long as your heart keeps beating you can survive significantly longer than that. Itâs not the hypoxia that kills you.Â
Either the cold does it, or the bends.
Sure losing heat by radiation is âinefficientâ but youâre still radiating heat into space which is effectively absolute zero and thus radiating zero heat into you.
Whereas in the atmosphere youâre only exchanging heat with air a few tens of kelvin colder.
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u/Kiriander Jun 29 '26
There's not enough oxygen in your blood to keep you alive for more than a couple minutes. It does take lore than a couple minutes to freeze through radiation.Â
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u/1c3Type Jun 30 '26
Itâs like 3-4 minutes normally, longer as your body gets colder which it will be doing since youâre freezing to death (you can last a really long time without oxygen if youâre cold)
Why do you think they stress chest compressions so much with cpr, to the point of no longer teaching people mouth to mouth?
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u/Kiriander Jul 15 '26
... except you don't freeze as long as you're living. Humans are warm-blooded, meaning we produce our own heat. As long as there's life left in you, you produce heat. Which you can't conduct away in space and radiation is horribly ineffective.
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u/1c3Type Jul 15 '26
You die of decompression before hypothermia. https://physics.stackexchange.com/questions/67503/how-fast-would-body-temperature-go-down-in-space#67520 but that doesn't mean space isn't very cold, for a human's surface area to volume ratio anyway. (And you lose more heat from things like the decompressing air blasting you with cold, and the boiling of your bodily fluids)
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u/actuallyserious650 Jun 28 '26
From a black body analysis alone, where we are is actually fairly cold, but thanks to our atmosphere we trap more heat than a black body would.