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The sun transfers its heat via electromagnetic radiation, and we named the modeled process "black body radiation." The amount of radiation received and absorbed depends on the material composition of the body and the cross-sectional area of the body perpendicular to the path of the radiation. As spacecraft travel to the inner solar system, the heat management becomes an immense problem. To counter the higher energy, the spacecraft are coated in reflective materials to deflect the heat and/or coated in materials that can absorb the heat, but not transfer the heat into the body of the spacecraft. Where things get really interesting in spacewalks. In the sunlight, temperatures can reach as high as 250 deg F, while plunging to -250 deg F in the shade. (Thanks, NASA: http://www.nasa.gov/audience/foreducators/spacesuits/facts/facts-index.html) Even though it is cold between the Sun and Earth, if you put a body there, it will heat up due to absorbing the radiation from the sun. It is only cold, because it is empty space without a physical body there to absorb the energy. I promise, if the Earth magically moved to Venus' orbit, the surface would be much, much hotter!Attached is the spectral output of the sun based on black body radiation (thanks, wikipedia). Notice how the power output of the sun at around 5,800 Kelvin, is nearly even across the visible spectrum. Which is why sunlight breaks into a nice even rainbow out a prism.
Neilep what makes you think that space between the sun and the earth is really cold? (And Cheese for that matter?)If there were absolutely nothing in it, it could not have any temperature at all.But there is just a tiny bit of stuff -- mostly hydrogen and a little dust -- and that is quite hot!It simply is not cold in space between the sun and the earth -- little heat stored there because there is little matter, but the temperature of the bit that there is is quite high!Mind you, this has nothing to do with the answer.
As a pilot, I have noticed that temperature decreasses about 2 degrees centigrade for each 1,000 feet of altitude. How long that continues I do not know. I have never been much higher than 25,000 feet. Thanks for comments. Joe L. Ogan