The math and physics that explain how blackbody radiation functions are so simple that I wonder why it isn't taught in elementary schools. Its all just basic geometry and algebra, but because it isn't taught in primary education, people think scientists are all wizards simply because they can calculate planetary surface temperatures. All they are doing is using basic geometry to find flux and then applying the Stefan–Boltzmann law.
A star has a certain total power output that can be calculated by knowing it's blackbody temperature (color temperature) and simple geometry can then be used to calculate the total amount of flux per unit area passing through any surface in orbit around the star. The 4th root of the flux is proportional to the surface temperature. Its all done using math that a 10 year old child could understand, but for whatever reason, it isn't taught to people younger than 20.