A vacuum is more of a heavy-duty insulator. On Earth, convection is often used for cooling, whether it be air or water. Either way, the heat of one object is transferred into a freely-flowing medium, of which there is a great quantity available. In space, you can irradiate heat. That's it. No convection, save for the occasional atom of hydrogen.
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Obviously if one side is facing directly into the sun the other side is not. I wonder how that would actually balance out then? Would the center of the object be 0 degree C then?
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Nope - bear in mind, 200C is not twice as hot as 100C. Celsius is zeroed at the freezing temperature of water, which is kind of abstract. Kelvin however, starts at absolute zero. So 200C translates to 473K, and 100C to 373K. I don't know if the Kelvin scale is linear; if it is though, something twice as hot as 100C would be 746K, or 473C.
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No air to "store" heat and you'll have some very very sharp temperature differences between objects exposed to sunlight and objects that are not. Would this work on the same premise here on Earth, where basically you have your hot side exposed to the sun, and the cold side exposed to high vacuum?
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There are many things to account for - how fast the material radiates heat into space, and how much mass is available. The entire object might heat up incredibly quickly, unable to radiate enough heat to let one side remain cold. Or it might radiate heat too fast, and thus stay cold. And distance from the sun is also a factor. NASA's Messenger spacecraft, en route to Mercury, has mirrors in front of its solar panels to shield them from the sun, and the entire array is at an angle, to further reduce the risk of overheating. The rest of the probe is protected by a reflective sun shield.
Then there's the Ulysses craft, out around Jupiter. It is at risk of freezing, as it's able to quickly radiate the little bit of heat is is receiving from the sun, and from its own power systems.