Luminescence

Luminescence is light emitted by a substance not caused by heat. In contrast, incandescence is light emitted by a substance as a result of heating.
Luminescence can be caused by chemical reactions, electrical energy, subatomic motions, or piezoelectricity (stress on a crystal). The term 'luminescence' was introduced in 1888 by Eilhard Wiedemann.
The dials, hands, scales and signs of aviation and navigational instruments and markings are often coated with luminescent materials in a process known as 'luminising'.