Why is space cold if there’s no matter in it?
In: Physics
The vacuum of space itself isn’t really cold, it’s empty. The things *in* the vacuum tend to be cold, because they are usually in space for long enough that they have radiated all of their heat away and aren’t getting much new energy. You tend to gain or lose heat in two different ways – through direct contact or through radiation. In space, you can’t gain or lose heat through direct contact most of the time, so you’re well insulated in that regard, but you can gain and lose heat by radiation. Since you radiate energy away faster than you gain it (unless you’re close to the sun), you will eventually cool down, but it’s nowhere near as fast as portrayed in movies.
In direct sunlight you might actually never freeze, since you can gain energy a lot quicker than you would radiate it, but again that depends on your distance from it. If something is blocking the sunlight, you’ll freeze in around 12-24 hours from radiating your heat away.
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