Incandescence is the emission of light (visible electromagnetic radiation) from a hot body due to its temperature. The term derives from the verb incandesce, to glow white. Practical In practice, virtually all substances start to glow visibly in the dark around 470°C (about 750K) with a very dull red color, assuming no chemical reaction takes place which emits light as a result of an exothermic reaction. Their incandescence isn't strictly zero below that temperature, but it's too weak in t… (More on Incandescent)