The sun warms up our planet but space is cold. If I lit a candle and stood 20 feet away, I could see the light but not feel the warmth. So, why do we feel warmth from the sun but space isn’t warmed by it?
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Answer: temperature is both a measurement of energy and of pressure. Let’s imagine we have a bunch of O2 atoms in a 1m^(3) box and we want to know the temperature of that box. First we might do some measurements to figure out how much energy each atom is carrying. The more energy they carry, the more often that they will collide with each other and the box. The more often these collisions happen, we call that “hot”. Vice versa for “cold”.
Next we need to know the pressure inside that box. This is easy to calculate because it’s just the energy of those atoms in a given volume and we already know both those values. If we were to make the box smaller, the temperature would go up because those atoms are in a smaller space so they collide with each other and the box more often. If we make the box larger, the temp will go down due to fewer overall collisions.
What does this have to do with outer space? Space is the biggest box the universe has to offer and it is 99.9% empty. So we have a massive box that has very little “stuff” inside of it so of course outer space is cold!
There are 3 types of heat transfer: conduction, convection, and radiation
Conduction is what we usually think of. If you touch something warm, the physical contact between you and the object is what allows heat to move
Convection is specifically with fluids (gasses and liquids) in motion. If you stand in front of a fan, the moving air transfers heat away from you. In some ways convection is just complex conduction as the particles near you are heated then move away and are replaced by new particles
Radiation is the final form, and does not require any sort of contact. Radiation heating is the weakest of the three types of heat transfer and can often be ignored. Put simply, infrared light (or any type of light really) from one object transfers energy to another object.
Because there is nothing in space, you cannot have convection or conduction between us and the sun. Instead, 100% of the heat energy coming from the sun is coming as light and transferring energy via Radiation.
Staying cold is just as much a problem as staying warm in space. If sunlight is hitting you there’s a massive amount of energy being transferred to you via IR Radiation. If the sunlight isn’t hitting you (say you’re behind the Earth), you will constantly be letting off IR radiation and losing heat. On earth we have air always touching us and the heat gained/lost from Radiation is negligible compared to conduction/convection with the air around us. But in space you don’t have an atmosphere as a thermal buffer, so heat gained/lost through Radiation becomes a lot more substantial
Heat, or warmth, is the transfer of energy from one medium to the next. It only occurs when objects are in contact with each other. So the best way to describe it is that heat can only propagate through conduction.
Since space is a vacuum, there is nothing to conduct heat with, so you end with thermal energy being “stuck” within an object.
Conversely, the light can travel through space because it travels through photons instead of thermal energy.
Space doesn’t have a temperature, it’s a vacuum.
Temperature is the kinetic energy of the particles inside an object. You can’t have temperature without particles.
Space doesn’t have a temperature, but objects in space have temperature because they’re made up of particles.
You know how the toilet seat feels cold when you first sit down but warm when you stand up? That’s because you “warmed it up” right? What does that mean? It means that heat was transferred from you to the toilet seat. This is something that always happens when two things touch. The thing that is warmer transfers heat to the thing that is cooler.
It’s that transfer of heat that we experience when we touch something that feels hot or cold. If we touch something that is cooler than us, the moment we touch it, heat transfers away from us and into it. That loss of heat feels like cold to us.
The reverse is also true. Have you ever played in the snow and then come inside and washed your hands with “cold” water? The water probably felt warm (or even uncomfortably hot) because your hands were actually colder than the cold water.
On earth, the air feels warm when the particles in the air (warmed by the sun) are warmer than your skin, so when they touch your skin, heat is transferred to you.
In space, however, there are no particles in the air. There’s not even any air. There’s nothing there to touch. There is nothing for heat to transfer to, so it is impossible for it to “warm up.”
Space is (mostly) empty, so the sun can’t heat it up because there’s nothing to heat up. If you put an object in space, that object is going to have some heat (all objects do) and it’s going to radiate heat to space. If that object can also evaporate (like moisture on exposed skin could), it will also lose heat by evaporation. That’s why when it comes to exposing living things to space, space is most often thought of as freezing.
However, if the object in space is also being lit by the sun, it’s going to receive heat from the sun’s radiation. So something like a satellite in orbit (or the surface of the moon) is going to get extremely hot on the sun side and extremely cold on the shade side. Managing this heating and cooling is a big part of spacecraft design (and why things sent to space are often either shiny or white – it’s to reflect the sunlight).
There is nothing, or almost nothing to be hot, or cold. Space is for argument sake is
completely empty, so there is nothing to be hot or cold. Put your self in front of the sun and you ill get very hot because you are now something, you will absorb the suns radiation just like Earth does, put your self somewhere the sun is blocked and you will get very cold as you radiate heat away
The heat from the Sun travels through space but doesn’t collect. It just keeps passing through. Like, if you go outside and stand in the sunlight, you dont get hot immediately. it takes some time to warm you up. Because the heat has to collect on the same spot to make something hot.
So space is cold because the heat doesnt stop and collect in amy spot. Other objects, like Planets, are warm because they collect the heat.
It is a common misconception that space is cold. Although temperature doesn’t work quite the same in a vacuum, the sun still heats anything the light touches. Outside of the spacestation on the sunny side, the temperatures can reach 250c. On the shady side, it can reach -250c.
It’s both. Depends if you’re in direct sunlight or not. In the near-vacuum of space, there’s very little to be warmed by the Sun. Space itself acts more as an insulator than a source of hot or cold.
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