Why is it cold in Space when the Sun is hundreds of thousands degrees C?

20 February 2011

Question

Why is it cold in Space when the Sun is hundreds of thousands of degrees C?

Answer

Dave - The Sun is incredibly hot, but the Sun is not throughout the whole of space. So, when you're sitting in space, in the Earth's orbit, you're getting hit by about the same amount of sun that you get if you're sitting on Earth, but the rest of you can see deep dark space which is about -270 degrees centigrade. So, you radiate heat into the deep dark space because anything warm glows in the infrared; and you're getting hit by sunlight, and the balance of those two is the temperature you'll sit at. In the Earth's orbit I think it's a bit below 0 degrees centigrade.

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