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Color and Light · entry 43 of 52
Glow-in-the-dark objects store light energy and release it slowly over several minutes.
The longer version
Phosphorescent materials absorb light and trap some of its energy in excited electron states that decay slowly. Instead of releasing everything at once, the material leaks photons over minutes, so it keeps glowing after the lamp is switched off. Charging works best with ultraviolet-rich light, which is why sunlight outperforms indoor lamps.
The delay distinguishes phosphorescence from fluorescence, which stops immediately when the source is removed. Zinc sulfide was the common ingredient for decades; newer compounds based on rare earths glow far longer. Heat speeds the release, so warming a glow object makes it brighter for a short time and then dark.
Where this entry sits
These facts explore how light behaves and how human eyes turn it into the colors we see. Along the way you meet rainbows, prisms, mirrors, shadows, lasers, and optical tricks that fool our vision every day. The full list sits on the Color and Light page, where every entry is listed in order.
More From Color and Light
Eight more entriesPolarized sunglasses reduce glare by blocking light waves vibrating in one particular direction.
Read 45Soap bubbles show shifting colors because thin films interfere with reflected light waves.
Read 46Oil on wet pavement shows a rainbow pattern for the same reason thin soap films do.
Read 47A peacock feather gets iridescent color from microscopic structures rather than from pigment.
Read 48Butterfly wings often shimmer with structural color produced by tiny scales instead of dyes.
Read 49Blue pigments are rare in nature, so most blue animals rely on structure instead.
Read 50Cameras capture color by filtering light through red, green, and blue sensors.
Read 51Printed images use cyan, magenta, yellow, and black ink to reproduce many colors.
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