🔥 Orbital Hull Plate: Radiative Cooling, Stefan-Boltzmann and Sunlit Floor (2D)

A hot metal plate floating in space, glowing and cooling by thermal radiation alone, with an optional sunlit face. Set the starting temperature, the thickness, the material, the emissivity, the solar absorptivity and the target temperature, and see the time-lapse cooling curve, the cooling time, the radiated power and the equilibrium temperature in sunlight. The Stefan-Boltzmann constant, the cooling law, the energy balance and the sunlit floor are checked numerically, with four in-page numerical checks.