Why is space cold?

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Offline thedoc

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Why is space cold?
« on: 11/07/2016 11:54:16 »
I'm teaching a bit of physics in my grade 4 class. We were having a lesson on heat transfer and when I was explaining 'radiation' I gave the example of the sun, even though it being so far away, the heat travels along way and can still warm us. Anther example was being warmed from a camp fire. Then a young girl asked, "Well, why is space cold then? If the sun is so hot, and we can feel it here on earth, why is it cold in space? As we move closer to the fire, we get warmer, the space between us an the fire is always hot and we can feel it all the time. Why isn't it like that in space? She's 9 - A budding scientist. Can you give me a simple explanation please? Thanks.
Asked by Lynne

                                        Visit the webpage for the podcast in which this question is answered.

[chapter podcast=1001386 track=16.07.05/Naked_Scientists_Show_16.07.05_1005373.mp3]  ...or Listen to the Answer[/chapter] or [download as MP3]

« Last Edit: 11/07/2016 11:54:16 by _system »



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« Reply #1 on: 10/07/2016 17:30:43 »
Heat is just molecules moving around an equilibrium point. The bigger the movement, the higher the temperature is perceived to be. It is a little bit like sound, which is propagated by molecules moving transversely. If there are no molecules around, meaning no gases, no liquid, no solid, like it is the case in open space outside our atmosphere, we hear no sound, and feel no heat. We see light coming from our sun when we are in outer space, but this light cannot transmit its energy to molecules of matter, since there is no matter to hit, except for the space suit the cosmonot is wearing, which does get hot.