Luminescence is light not generated by high temperatures alone. It is different from incandescence, in that it usually occurs at low temperatures and is thus a form of cold body radiation. It can be caused by, for example, chemical reactions, electrical energy, subatomic motions, or stress on a crystal. The following kinds of luminescence are known:
Historically, radioactivity was first thought of as a form of "radioluminescence", although it is today considered to be separate since it involves more than electromagnetic radiation.
The process of coating dials, hands, scales and signs on, particularly, aviation and navigational instruments and markings with luminescent materials is known as luminising.
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