ABSTRACT
Thermal radiation serves as an essential ingredient for the formation of life in the cosmos. Thermal radiation represents a finite region of the electromagnetic spectrum. Thermal radiation is the transfer of energy by electromagnetic waves, which have a range of wavelengths. The idea that the energy in a light beam consists of numerous amounts of photons simply highlights the fact that light is a form of energy. The chapter presents the nature of thermal radiation, its characteristics, and properties. The experiment requires an understanding of the concepts of solar radiation intensity levels and measurements when using a solar radiation meter. For a better understanding of thermal radiation, it will be necessary to study several different disciplines: electromagnetic theory; statistical mechanics; quantum mechanics; and thermodynamics. The Sun supplies an inexhaustible amount of solar thermal energy to the universe. Solar radiation measurements often include total radiation, in energy per unit time per unit area, on a horizontal surface.
