Been reading about early space exploration again, especially Sputnik 2 (1957) and Venera 1 (1961). Both of these suffered from overheating.
It strikes me that a metal object will easily "absorb" the Sun's rays, which are not mitigated by any atmosphere. A deep space probe will not have the protection of Earth's magnetic field either.
So it seems to me that a metal object, if warmed by the Sun, will cook anything inside of it. So how is a spacecraft engineered to not overheat? Especially for something like a solar sensor or solar panel, which cannot be covered by a reflective sheet.