Glow in the dark is possible due to photoluminescence, in which materials absorb light energy and then gradually releases it as visible light in the dark.
The photoluminescence process relies on substances that are called phosphors, which absorb light from sources such as sunlight or artificial light and store the energy.
And when the source of light is removed, the phosphors then release the stored energy as visible light and creates the glow effect.
Phosphors, which are often zinc sulfide or strontium aluminate, absorb light energy, particularly in the visible and ultraviolet wavelengths.
The absorbed light energy then excites the electrons that are within the phosphor material and cause them to jump to a higher energy level.
And when the material is in the dark, the excited electrons gradually return to their normal energy level, releasing the stored energy as photons of visible light.
The duration of the glow also depends on the type of phosphor and the intensity of the initial light exposure.
The process is also called photoluminescence, which is a safe and non radioactive way of creating glowing effects.
And some glow in the dark products also utilize chemiluminescence, where a chemical reaction produces light, like in glow sticks.