How can planets with no atmosphere and different orbits around the sun have the same surface temp?
There are two primary sources of heat for a planet: external (largely resulting from exposure to a star, but possibly also from another nearby planet reflecting solar energy or producing its own energy) and internal (mostly resulting from gravitational compression producing heat, but also from nuclear decay and chemical reaction– to a very small extent, comparatively). A planet farther away can compensate by having a much larger mass, and/or by being composed of an over-abundance of radioactive material (although this is rather unlikely), thus producing more internal energy. However, even if the two planets had the same mass (with the same internal energy), the scenario of having the same surface temperature might still be possible. Surface temperature due to external heating is not solely a function of high much energy an object receives, but also how well that object retains the heat. If the nearer planet is highly reflective, the energy is easily lost, and it remains quite cold. If
