[worrycue]

Black surfaces are good at absorbing AND radiating heat. I think that’s why the SR-71 was painted black. The amount of heat it got from absorbing the sun’s rays probably paled in comparison to the heat it radiated from all the friction as it flew.

[George83728]

From what I understand, the SR-71's black paint did radiate thermal energy, but also made the plane harder to see in visible light at night, and on radar. It was a RAM coating impregnated with iron to reduce the radar cross section. The characteristic chines along the edge of the fuselage were also meant to reduce the radar cross section.