👉 Unradiant is a term in physics and astronomy used to describe a state of matter that is highly stable, without any spontaneous emission or absorption. It is characterized by its high opacity (i.e., it has very low reflectivity) and its ability to absorb all wavelengths of light except for the visible ones. In terms of radiative transfer, an unradiant medium would be one where no photons are emitted from a given point in space or time. This means that there is no change in
