Like i understand there isn’t a lot of things for the heat from Stars to bounce off of but what causes Space itself to be cold? Is it naturally always cold and if so why?
In: Planetary Science
kinda contradicting some of the answers here, but not really, because it’s important to get the concept right.
strictly speaking, “space” isn’t cold, it’s hot. when we say something is “hot” or “cold” we’re talking about how fast particles are moving. and particles in space are *real* fast. the problem is, space is very very empty. so there’s very few little of these particles.
it’s important to distinguish these concepts because it has important ramifications – because space isn’t really “cold” it’s actually a challenge to get rid of excess heat when necessary – the ISS has these large things that jut out into space that are *not* solar panels (though they have them), they are just part of the cooling system, angled away from the sun, just to try maximize heat just radiating away (on earth, heat can convect away through the interaction of hold particles and cold particles, in space convection isn’t possible you can only radiate, which is much slower)
edit: to the folks saying that cold is simply the absence of heat, or that cold is the default state of a vacuum, that’s wrong. as i mention, what we conceive of as “cold” is simply lower on the spectrum of particles moving around. a pure vacuum has almost no concept of cold because there’s nothing to actually move around. if you were somehow put into a vacuum while alive, you wouldn’t feel cold, at least for a while – there’s nothing to take heat away from you in that vacuum the way air molecules could. in fact, if you were in the vacuum of space but with a clear line of sight to the sun, you would get really hot because the sun would be imparting way more energy to you via radiation than you would be losing heat via radiation.
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