If heat cannot travel through a vacuum why does the sun feel hot?

06 September 2016

Question

Which way is North when you leave the earth?
Which way is up when you are in space?
If heat cannot travel through a vacuum why does the sun feel hot?

Answer

Kat Arney put this to Caroline Steel...

Caroline - So we kind of mentioned this earlier when we were talking about ways to die in space. So, heat does travel through a vacuum. It just doesn't travel in a normal kind of conduction way that we quite often automatically think of. So for something to conduct like when you put a metal spoon in a saucepan and it gets really hot, you acquire particles as the heat energy is transferred through the particles. But heat can also travel through radiation which is part of the electromagnetic spectrum so waves travel from the Sun to the Earth and heat up the atmosphere. So yeah, heat does travel through space and it probably would give you really bad sunburn if you were stuck out there with no suit or anything.

Kat - Is this why things like you get infrared heating lamps and stuff like that?

Caroline - That's also radiation, yeah. So it's a different way of transferring heat. It's using heat waves rather than sort of transferring heat through collisions of particles.

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