Fluorescence
The glow of a material that absorbs light of one colour, often ultraviolet, and gives out another.
Also: fluorescent colour, day-glo
A fluorescent material takes in light we may not be able to see, such as ultraviolet, and at once sends out visible light. Because it gives off more visible light than falls on it, it can look brighter than any ordinary colour. Highlighter pens and safety vests rely on this. Washing powders contain fluorescent brighteners that make whites glow slightly blue. The glow stops the moment the light source is removed. Banknotes, minerals, scorpions and some corals fluoresce under an ultraviolet lamp.